research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 72| Part 2| February 2016| Pages 120-123
doi:10.1107/S205698901502441X

Crystal structure of a Pd4 carbonyl tri­phenyl­phosphane cluster [Pd4(CO)5(PPh3)4]·2C4H8O, comparing solvates

CROSSMARK_Color_square_no_text.svg
Koen Robeyns,a Christopher Willocq,a Bernard Tinant,a Michel Devillersa and Sophie Hermansa*

aInstitute of Condensed Matter and Nanosciences (IMCN), Université Catholique de Louvain, 1 Place Louis Pasteur, B 1348 Louvain-la-Neuve, Belgium
*Correspondence e-mail: sophie.hermans@uclouvain.be

Edited by A. J. Lough, University of Toronto, Canada (Received 3 December 2015; accepted 18 December 2015; online 6 January 2016)

Attempts to synthesize Au–Pd heterometallic compounds from homonuclear palladium or gold complexes, [Pd(PtBu2)2] and [Au(PPh3)Cl] in a tetra­hydro­furan (THF) solution under a CO atmosphere resulted in a homonuclear Pd cluster, namely penta­kis­(μ-carbonyl-κ2C:C)tetra­kis­(tri­phenyl­phosphane-κP)tetrapalladium(5 Pd—Pd) tetra­hydro­furan disolvate, [Pd4(CO)5(C18H15P)4]·2C4H8O. The complex mol­ecule lies on a twofold rotation axis. The crystal structure is described in relation to the CH2Cl2 solvate previously determined by our group [Willocq et al. (2011[Willocq, C., Tinant, B., Aubriet, F., Carré, V., Devillers, M. & Hermans, S. (2011). Inorg. Chim. Acta, 373, 233-242.]). Inorg. Chim. Acta, 373, 233–242], and in particular to the desolvated structure [Feltham et al. (1985[Feltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503-1510.]). Inorg. Chem. 24, 1503–1510]. It is assumed that the title compound transforms into the latter structure, upon gradual loss of solvent mol­ecules. In the title compound, the symmetry-unique THF solvent mol­ecule is linked to the complex mol­ecule by a weak C—H⋯O hydrogen bond. Contributions of disordered solvent molecules to the diffraction intensities, most likely associated with methanol, were removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9–18] algorithm.

CCDC reference: 1443364

1. Chemical context

Heterometallic compounds are ideal precursors for mixed oxides or mixed-metal nanoparticles, especially when the two considered metals are difficult to alloy. In the case of the Pd–Au combination, a tremendous amount of work has been carried out recently in heterogeneous catalysis to prepare supported bimetallic catalysts with a fine control over composition and size of the supported heterometal nanoparticles (Paalanen et al., 2013[Paalanen, P., Weckhuysen, B. M. & Sankar, M. (2013). Catal. Sci. Technol. 3, 2869-2880.]). These materials find, for example, application in the direct synthesis of hydrogen peroxide from hydrogen and oxygen (Edwards et al., 2015[Edwards, J. K., Freakley, S. J., Lewis, R. J., Pritchard, J. C. & Hutchings, G. J. (2015). Catal. Today, 248, 3-9.]), or liquid-phase oxidation of alcohols and aldehydes (Villa et al., 2015[Villa, A., Wang, D., Su, D. S. & Prati, L. (2015). Catal. Sci. Technol. 5, 55-68.]; Hermans & Devillers, 2005[Hermans, S. & Devillers, M. (2005). Catal. Lett. 99, 55-64.]; Hermans et al., 2010[Hermans, S., Deffernez, A. & Devillers, M. (2010). Catal. Today, 157, 77-82.], 2011[Hermans, S., Deffernez, A. & Devillers, M. (2011). Appl. Catal. Gen. 395, 19-27.]). However, synthesizing mol­ecular compounds presenting a hetero metal–metal bond is challenging. Several strategies have been described, such as reactions of metal salts in the presence of a reducing agent or reactions under irradiation (favoring formation of metal–metal bonds). In the present work, we explore the reactivity of Au and Pd compounds in a CO atmosphere, with the hope of providing the reducing agent and additional ligands through dissolved carbon monoxide. The direct synthesis of Au–Pd heterometallic complexes has already been achieved using similar strategies, for example starting from [Pd(PPh3)2Cl2] and [Au(PPh3)NO3] in the presence of NaBH4 (Ito et al., 1991[Ito, L. N., Felicissimo, A. M. P. & Pignolet, L. H. (1991). Inorg. Chem. 30, 988-994.]; Quintilio et al., 1994[Quintilio, W., Sotelo, A. & Felicissimo, A. M. P. (1994). Spectrosc. Lett. 27, 605-611.]). One major drawback of this type of strategy is that the product formed is unpredictable, with easy cluster formation by aggregation and homometal bond formation. We have devised in parallel a more predictable synthesis method for Au–Pd compounds by adding a cationic Au fragment to a reduced Pd species (Willocq et al., 2011[Willocq, C., Tinant, B., Aubriet, F., Carré, V., Devillers, M. & Hermans, S. (2011). Inorg. Chim. Acta, 373, 233-242.]). Here we describe a homometallic Pd4 cluster formed by reductive carbonyl­ation and coalescence of a Pd complex in presence of an Au phosphine compound. The reported cluster is closely related to known Pd4 cluster structures (Willocq et al., 2011[Willocq, C., Tinant, B., Aubriet, F., Carré, V., Devillers, M. & Hermans, S. (2011). Inorg. Chim. Acta, 373, 233-242.]; Mednikov et al., 1987[Mednikov, E. G., Eremenko, L. A., Slovokhotov, Y. L., Struchkov, Y. T. & Gubin, S. P. (1987). Koord. Khim. 13, 979.]; Feltham et al., 1985[Feltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503-1510.]).

[Scheme 1]

2. Structural commentary

The structure of the Pd cluster (Fig. 1[link]) shows inter­nal symmetry and is located on a twofold rotation axis, passing through the central carbonyl, giving four complex mol­ecules in the unit cell (Z′ = 0.5). Crystallized from a THF/MeOH mixture, the reported structure is a THF solvate, revealing eight tetra­hydro­furan mol­ecules in the unit cell. Around the inversion centres, 60 Å cavities are located which were treated by the PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]) SQUEEZE (Spek, 2015[Spek, A. L. (2015). Acta Cryst. C71, 9-18.]) algorithm, accounting to 15 electrons. A single peak, on the special position, was visible in this cavity, which is believed to be the oxygen atom of a partially occupied and disordered MeOH mol­ecule. Partial evaporation of the solvent mol­ecules probably explains the limited resolution of the collected data. Reflection data up to 0.94 Å were used during refinement, this being the best diffracting crystal amongst several tested.

[Figure 1]
Figure 1
Molecular structure of the title compound, showing displacement ellipsoids drawn at the 50% probability level. [Symmetry code: (a) −x, y, −z + [{1\over 2}].] Only the symmetry-unique THF solvent mol­ecule is shown.

The central unit of the complex consists of four Pd atoms at the corners of a distorted tetra­hedron. Of the six edges, five are occupied by bridging carbonyl ligands, the remaining one has a non-bonding Pd⋯Pd distance of 3.170 (1) Å. The bonding Pd—Pd distances are in the range 2.7381 (8)–2.8006 (12) Å (Table 1[link]). The same compound had been crystallized earlier by our group (Willocq et al., 2011[Willocq, C., Tinant, B., Aubriet, F., Carré, V., Devillers, M. & Hermans, S. (2011). Inorg. Chim. Acta, 373, 233-242.]) as a CH2Cl2 solvate in the triclinic space group P[\overline{1}]. The mol­ecular geometry of both structures is quite different, the most pronounced difference being the lack of inter­nal symmetry in the P[\overline{1}] structure, which can be extended to the symmetry of the Pd core. The Pd—Pd distances opposite the non-bonding Pd—Pd are very similar, 2.801 (1) and 2.805 (1) Å (P[\overline{1}]). Although the average of the four remaining Pd—Pd bond lengths in the two structures is quite similar (2.741 Å for the current structure and 2.746 Å for the triclinic structure), the bond-length distribution is quite different, showing equal bond lengths for the current structure and two shorter [2.678 (1) and 2.720 (1) Å] and two longer ones [2.797 (1) and 2.790 (1) Å] for the triclinic structure.

Table 1
Selected bond lengths (Å)

Pd1—Pd2 2.7381 (8) Pd2—P4 2.3208 (15)
Pd1—Pd2i 2.7446 (9) Pd2—Pd1i 2.7446 (9)
Pd1—Pd1i 3.1704 (14) Pd2—Pd2i 2.8006 (12)
Symmetry code: (i) [-x, y, -z+{\script{1\over 2}}].

No classical hydrogen-bond inter­actions are observed, but a weak C—H ⋯O inter­action (Table 2[link]) can be considered to the oxygen atom of the THF mol­ecule.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
C19—H19⋯O100ii 0.95 2.43 3.282 (8) 149
Symmetry code: (ii) [x-{\script{1\over 2}}, y+{\script{1\over 2}}, z].

3. Database survey

A survey of the Cambridge Structural Database (Groom & Allen, 2014[Groom, C. R. & Allen, F. H. (2014). Angew. Chem. Int. Ed. 53, 662-671.]) revealed two more occurrences of the title compound, both crystallized in the C2/c space group. In the paper by Mednikov et al. (1987[Mednikov, E. G., Eremenko, L. A., Slovokhotov, Y. L., Struchkov, Y. T. & Gubin, S. P. (1987). Koord. Khim. 13, 979.]) the homonuclear Pd cluster is reported as a co-former, together with a trinuclear Pd cluster [Pd3(CO)3(PPh3)4], here as well the Pd cluster is found onto a twofold rotation axis and superposition of both mol­ecular entities reveals similar features, right up to similar orientations of the tri­phenyl­phosphines.

The second occurrence is however much more inter­esting as the structure of Feltham et al. (1985[Feltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503-1510.]) shows remarkable similarities with the reported structure, not only with respect to the mol­ecular conformation – the r.m.s. deviation between the two structures is 0.757 Å for all atoms, and 0.356 Å when omitting the phenyl rings – but also with respect to the overall crystal packing. Closer inspection of the unit-cell parameters, listed below, reveals that for both structures only the a axis differs significantly by more than 2 Å (2.297 Å):

a = 27.254 (9), b = 16.016 (6), c = 17.938 (7) Å, β = 105.92 (2)°, V = 7530.0 Å3, 120 K (title compound);

a = 24.957 (5), b = 16.138 (3), c = 17.758 (3) Å, β = 103.47 (2)°, V = 6955.4 Å3, RT, (Feltham et al., 1985[Feltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503-1510.]).

While the Feltham et al. (1985[Feltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503-1510.]) structure contains a total of 400 Å3 of voids distributed over six sites (pore sizes from 5–32 Å3), none of these is big enough to host even small solvent mol­ecules, characterizing this structure as solvent-free. Gradual loss of solvent mol­ecules is believed to provoke a transformation from the solvent-rich title compound to the desolvated structure reported by Feltham et al. (1985[Feltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503-1510.]). The reported problems during crystal harvesting of the latter structure (see section 4) tends to support this hypothesis. The transformation itself appears to occur in a sequential process where two types of solvent cavities gradually lose their solvent mol­ecules, leading to a contraction of the a axis. The first affected cavities are the 61 Å3 voids treated by SQUEEZE (Spek, 2015[Spek, A. L. (2015). Acta Cryst. C71, 9-18.]) in the current structure, followed by the cavity hosting the loosely trapped THF mol­ecule (289 Å3). After correcting for the inter­stitial voids observed in the contracted structure, the volume loss during the transformation is in complete agreement with the solvent loss in both cavities.

Fig. 2[link] shows the packing overlay by pairwise fitting of the Pd atoms of the reported structure and the structure of Feltham et al. (1985[Feltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503-1510.]) (all Pd atoms within one unit cell were considered); evaporation of the THF mol­ecules and small rearrangements of the homonuclear cluster allows the transformation of the solvated structure into the solvent-free analogue to be completed. This transformation only involves one dimension and a projection along the a axis of the superimposed unit cells reveals practically fully overlapped mol­ecules, even when considering the orientation of the phenyl rings.

[Figure 2]
Figure 2
Packing overlay of the title compound measured at 120 K and the solvent-free structure of Feltham et al. (1985[Feltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503-1510.]) measured at room temperature, obtained by pairwise fitting of all Pd atoms of the four mol­ecules in the unit cell. The projection along the b axis reveals that, upon evaporation of the solvent mol­ecules, the unit cell contracts, while keeping the global packing arrangement. Phenyl rings have been omitted for clarity.

4. Synthesis and crystallization

The synthesis of the title compound was an attempt to obtain mixed Au–Pd complexes in a one-step reaction. Through a THF solution of [Pd(PtBu3)2] and [Au(PPh3)Cl] carbon monoxide gas was passed and the solid material left after evaporation of the solvent was characterized by NMR and IR spectroscopy. One intense IR band at 1870 cm−1 indicated the formation of a complex with CO ligands. 31P NMR showed two signals at 28.1 and 97.2 p.p.m. with a 4:1 ratio, which indicate the presence of two types of phosphines, while the 1H NMR indicated the presence of both tri­phenyl­phosphine and tri-tert-butyl­phosphine. Dissolution of the solid in a THF/MeOH mixture yielded red crystals which were suitable for X-ray diffraction. Rather than a mixed Au–Pd species, the crystals contained a homonuclear Pd complex.

Previously the synthesis of the title compound was reported as the reduction of an oxygen-free CH2Cl2 solution of [Pd(NO2)2(PPh3)3] under CO. Crystals were formed upon cooling after addition of CO-saturated hexane and were reported to decompose rapidly and could finally be measured at room temperature in a CO-filled sealed capillary (Feltham et al., 1985[Feltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503-1510.]). The homonuclear Pd4 cluster can also be synthesized by the reaction of [Pd2(dba)3] (dba is dibenzyl­idene­acetone) and three equivalents of PPh3 under CO (Willocq et al., 2011[Willocq, C., Tinant, B., Aubriet, F., Carré, V., Devillers, M. & Hermans, S. (2011). Inorg. Chim. Acta, 373, 233-242.]).

5. Refinement

Crystal data and structure refinement details are summarized in Table 3[link]. Data were collected on a MAR345 image plate, using Mo Kα radiation generated on a Rigaku UltraX 18S generator (Zr filter). Diffaction data were not corrected for absorption, but the data collection mode with high redundancy, partially takes the absorption phenomena into account. (111 images, ΔΦ = 2°, 21617 reflections measured for 4740 independent reflections). H atoms were placed at calculated positions with isotropic temperature factors fixed at 1.2Ueq of the parent atom.

Table 3
Experimental details

Crystal data
Chemical formula [Pd4(CO)5(C18H15P)4]·2C4H8O
Mr 1758.93
Crystal system, space group Monoclinic, C2/c
Temperature (K) 120
a, b, c (Å) 27.254 (9), 16.016 (6), 17.938 (7)
β (°) 105.92 (2)
V (Å3) 7530 (5)
Z 4
Radiation type Mo Kα
μ (mm−1) 1.08
Crystal size (mm) 0.18 × 0.12 × 0.05
 
Data collection
Diffractometer MAR345 image plate
No. of measured, independent and observed [I > 2σ(I)] reflections 9236, 4739, 3938
Rint 0.037
θmax (°) 22.2
(sin θ/λ)max (Å−1) 0.532
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.086, 1.04
No. of reflections 4739
No. of parameters 453
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.54, −0.53
Computer programs: mar345 (Klein, 1998[Klein, C. (1998). mar345. X-ray Research GmbH, Norderstedt, Germany.]), marHKL (Klein & Bartels, 2000[Klein, C. & Bartels, K. (2000). marHKL. X-ray Research GmbH, Norderstedt, Germany.]), SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2014 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]), Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information

CCDC reference: 1443364

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S205698901502441X/lh5801sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S205698901502441X/lh5801Isup2.hkl

Supporting information file. DOI: 10.1107/S205698901502441X/lh5801Isup3.cdx

checkCIF report


Chemical context top

Heterometallic compounds are ideal precursors for mixed oxides or mixed-metal nanoparticles, especially when the two considered metals are difficult to alloy. In the case of the Pd–Au combination, a tremendous amount of work has been carried out recently in heterogeneous catalysis to prepare supported bimetallic catalysts with a fine control over composition and size of the supported heterometal nanoparticles (Paalanen et al., 2013). These materials find, for example, application in the direct synthesis of hydrogen peroxide from hydrogen and oxygen (Edwards et al., 2015), or liquid-phase oxidation of alcohols and aldehydes (Villa et al., 2015; Hermans & Devillers, 2005; Hermans et al., 2010, 2011). However, synthesizing molecular compounds presenting a hetero metal–metal bond is challenging. Several strategies have been described, such as reactions of metal salts in the presence of a reducing agent or reactions under irradiation (favoring formation of metal–metal bonds). In the present work, we explore the reactivity of Au and Pd compounds in a CO atmosphere, with the hope of providing the reducing agent and additional ligands through dissolved carbon monoxide. The direct synthesis of Au–Pd heterometallic complexes has already been achieved using similar strategies, for example starting from [Pd(PPh3)2Cl2] and [Au(PPh3)NO3] in the presence of NaBH4 (Ito et al., 1991; Quintilio et al., 1994). One major drawback of this type of strategy is that the product formed is unpredi­cta­ble, with easy cluster formation by aggregation and homometal bond formation. We have devised in parallel a more predi­cta­ble synthesis method for Au–Pd compounds by adding a cationic Au fragment to a reduced Pd species (Willocq et al., 2011). Here we describe a homometallic Pd4 cluster formed by reductive carbonyl­ation and coalescence of a Pd complex in presence of an Au phosphine compound. The reported cluster is closely related to known Pd4 cluster structures (Willocq et al., 2011; Mednikov et al., 1987; Feltham et al., 1985).

Structural commentary top

The reported homonuclear Pd cluster, shown in Fig. 1, was measured at 120 K and crystallizes in the monoclinic space group C2/c; the structure shows inter­nal symmetry and is located on a twofold rotation axis, passing through the central carbonyl, giving four complex molecules in the unit cell (Z' = 1/2). Crystallized from a THF/MeOH mixture, the reported structure is a THF solvate, revealing eight tetra­hydro­furan molecules in the unit cell. Around the inversion centres, 60 Å cavities are located which were treated by the PLATON (Spek, 2009) SQUEEZE (Spek, 2015) algorithm, accounting to 15 electrons. A single peak, on the special position, was visible in this cavity, which is believed to be the oxygen atom of a partially occupied and disordered MeOH molecule. Partial evaporation of the solvent molecules probably explains the limited resolution of the collected data. Reflection data up to 0.94 Å were used during refinement, this being the best diffracting crystal amongst several tested.

The central unit of the complex consists of four Pd atoms at the corners of a distorted tetra­hedron. Of the six edges, five are occupied by bridging carbonyl ligands, the remaining one has a non-bonded Pd···Pd distance of 3.170 (1) Å. The bonded Pd—Pd distances are in the range 2.7381 (8)–2.8006 (12) Å (Table 1). The same compound had been crystallized earlier by our group (Willocq et al., 2011) as a CH2Cl2 solvate in the triclinic space group P1. The molecular geometry of both structures is quite different, the most pronounced difference being the lack of inter­nal symmetry in the P1 structure, which can be extended to the symmetry of the Pd core. The Pd—Pd distances opposite the non-bonded Pd—Pd are very similar, 2.801 (1) and 2.805 (1) Å (P1). Although the average of the four remaining Pd—Pd bond lengths in the two structures is quite similar (2.741 Å for the current structure and 2.746 Å for the triclinic structure), the bond-length distribution is quite different, showing equal bond lengths for the current structure and two shorter [2.678 (1) and 2.720 (1) Å] and two longer ones [2.797 (1) and 2.790 (1) Å] for the triclinic structure.

No classical hydrogen-bond inter­actions are observed, but a weak C—H ···O inter­action (Table 2) can be considered to the oxygen atom of the THF molecule.

Database survey top

A survey of the Cambridge Structural Database (Groom & Allen, 2014) revealed two more occurrences of the title compound, both crystallized in the C2/c space group. In the paper by Mednikov et al. (1987) the homonuclear Pd cluster is reported as a co-former, together with a trinuclear Pd cluster [Pd3(CO)3(PPh3)4], here as well the Pd cluster is found onto a twofold axis and superposition of both molecular entities reveals similar features, right up to similar orientations of the tri­phenyl­phosphines.

The second occurrence is however much more inter­esting as the structure of Feltham et al. (1985) shows remarkable similarities with the reported structure, not only with respect to the molecular conformation – the r.m.s. deviation between the two structures is 0.757 Å for all atoms, and 0.356 Å when omitting the phenyl rings – but also with respect to the overall crystal packing. Closer inspection of the unit-cell parameters, listed below, reveals that for both structures only the a axis differs significantly by more than 2 Å (2.297 Å):

a = 27.254 (9), b = 16.016 (6), c = 17.938 (7) Å, β = 105.92 (2)°, V = 7530.0 Å3, 120 K (title compound);

a = 24.957 (5), b = 16.138 (3), c = 17.758 (3) Å, β = 103.47 (2)°, V = 6955.4 Å3, RT, (Feltham et al., 1985).

While the Feltham et al. (1985) structure contains a total of 400 Å3 of voids distributed over six sites (pore sizes from 5–32 Å3), none of these is big enough to host even small solvent molecules, characterizing this structure as solvent-free. Gradual loss of solvent molecules is believed to provoke a transformation from the solvent-rich title compound to the desolvated structure reported by Feltham et al. (1985). The reported problems during crystal harvesting of the latter structure (see section 4) tends to support this hypothesis. The transformation itself appears to occur in a sequential process where two types of solvent cavities gradually lose their solvent molecules, leading to a contraction of the a axis. The first affected cavities are the 61 Å3 voids treated by SQUEEZE in the current structure, followed by the cavity hosting the loosely trapped THF molecule (289 Å3). After correcting for the inter­stitial voids observed in the contracted structure, the volume loss during the transformation is in complete agreement with the solvent loss in both cavities.

Fig. 2 shows the packing overlay by pairwise fitting of the Pd atoms of the reported structure and the structure of Feltham et al. (1985) (all Pd atoms within one unit cell were considered); evaporation of the THF molecules and small rearrangements of the homonuclear cluster allows the transformation of the solvated structure into the solvent-free analogue to be completed. This transformation only involves one dimension and a projection along the a axis of the superimposed unit cells reveals practically fully overlapped molecules, even when considering the orientation of the phenyl rings.

Synthesis and crystallization top

The synthesis of the title compound was an attempt to obtain mixed Au–Pd complexes in a one-step reaction. Through a THF solution of [Pd(PtBu3)2] and [Au(PPh3)Cl] carbon monoxide gas was passed and the solid material left after evaporation of the solvent was characterized by NMR and IR. One intense IR band at 1870 cm−1 indicated the formation of a complex with CO ligands. 31P NMR showed two signals at 28.1 and 97.2 p.p.m. with a 4:1 ratio, which indicate the presence of two types of phosphines, while the 1H NMR indicated the presence of both tri­phenyl­phosphine and tri-tert-butyl­phosphine. Dissolution of the solid in a THF/MeOH mixture yielded red crystals which were suitable for X-ray diffraction. Rather than a mixed Au–Pd species, the crystals contained a homonuclear Pd complex.

Previously the synthesis of the title compound was reported as the reduction of an oxygen-free CH2Cl2 solution of [Pd(NO2)2(PPh3)3] under CO. Crystals were formed upon cooling after addition of CO-saturated hexane and were reported to decompose rapidly and could finally be measured at room temperature in a CO-filled sealed capillary (Feltham et al., 1985). The homonuclear Pd4 cluster can also be synthesized by the reaction of [Pd2(dba)3] and three equivalents of PPh3 under CO (Willocq et al., 2011).

Refinement top

Crystal data and structure refinement details are summarized in Table 3. Data were collected on a MAR345 image plate, using Mo Kα radiation generated on a Rigaku UltraX 18S generator (Zr filter). The reflections were integrated by marHKL; the data were not corrected for absorption, but the data collection mode with high redundancy, partially takes the absorption phenomena into account. (111 images, ΔΦ = 2°, 21617 reflections measured for 4740 independent reflections). H atoms were placed at calculated positions with isotropic temperature factors fixed at 1.2Ueq of the parent atom.

Structure description top

Heterometallic compounds are ideal precursors for mixed oxides or mixed-metal nanoparticles, especially when the two considered metals are difficult to alloy. In the case of the Pd–Au combination, a tremendous amount of work has been carried out recently in heterogeneous catalysis to prepare supported bimetallic catalysts with a fine control over composition and size of the supported heterometal nanoparticles (Paalanen et al., 2013). These materials find, for example, application in the direct synthesis of hydrogen peroxide from hydrogen and oxygen (Edwards et al., 2015), or liquid-phase oxidation of alcohols and aldehydes (Villa et al., 2015; Hermans & Devillers, 2005; Hermans et al., 2010, 2011). However, synthesizing molecular compounds presenting a hetero metal–metal bond is challenging. Several strategies have been described, such as reactions of metal salts in the presence of a reducing agent or reactions under irradiation (favoring formation of metal–metal bonds). In the present work, we explore the reactivity of Au and Pd compounds in a CO atmosphere, with the hope of providing the reducing agent and additional ligands through dissolved carbon monoxide. The direct synthesis of Au–Pd heterometallic complexes has already been achieved using similar strategies, for example starting from [Pd(PPh3)2Cl2] and [Au(PPh3)NO3] in the presence of NaBH4 (Ito et al., 1991; Quintilio et al., 1994). One major drawback of this type of strategy is that the product formed is unpredi­cta­ble, with easy cluster formation by aggregation and homometal bond formation. We have devised in parallel a more predi­cta­ble synthesis method for Au–Pd compounds by adding a cationic Au fragment to a reduced Pd species (Willocq et al., 2011). Here we describe a homometallic Pd4 cluster formed by reductive carbonyl­ation and coalescence of a Pd complex in presence of an Au phosphine compound. The reported cluster is closely related to known Pd4 cluster structures (Willocq et al., 2011; Mednikov et al., 1987; Feltham et al., 1985).

The reported homonuclear Pd cluster, shown in Fig. 1, was measured at 120 K and crystallizes in the monoclinic space group C2/c; the structure shows inter­nal symmetry and is located on a twofold rotation axis, passing through the central carbonyl, giving four complex molecules in the unit cell (Z' = 1/2). Crystallized from a THF/MeOH mixture, the reported structure is a THF solvate, revealing eight tetra­hydro­furan molecules in the unit cell. Around the inversion centres, 60 Å cavities are located which were treated by the PLATON (Spek, 2009) SQUEEZE (Spek, 2015) algorithm, accounting to 15 electrons. A single peak, on the special position, was visible in this cavity, which is believed to be the oxygen atom of a partially occupied and disordered MeOH molecule. Partial evaporation of the solvent molecules probably explains the limited resolution of the collected data. Reflection data up to 0.94 Å were used during refinement, this being the best diffracting crystal amongst several tested.

The central unit of the complex consists of four Pd atoms at the corners of a distorted tetra­hedron. Of the six edges, five are occupied by bridging carbonyl ligands, the remaining one has a non-bonded Pd···Pd distance of 3.170 (1) Å. The bonded Pd—Pd distances are in the range 2.7381 (8)–2.8006 (12) Å (Table 1). The same compound had been crystallized earlier by our group (Willocq et al., 2011) as a CH2Cl2 solvate in the triclinic space group P1. The molecular geometry of both structures is quite different, the most pronounced difference being the lack of inter­nal symmetry in the P1 structure, which can be extended to the symmetry of the Pd core. The Pd—Pd distances opposite the non-bonded Pd—Pd are very similar, 2.801 (1) and 2.805 (1) Å (P1). Although the average of the four remaining Pd—Pd bond lengths in the two structures is quite similar (2.741 Å for the current structure and 2.746 Å for the triclinic structure), the bond-length distribution is quite different, showing equal bond lengths for the current structure and two shorter [2.678 (1) and 2.720 (1) Å] and two longer ones [2.797 (1) and 2.790 (1) Å] for the triclinic structure.

No classical hydrogen-bond inter­actions are observed, but a weak C—H ···O inter­action (Table 2) can be considered to the oxygen atom of the THF molecule.

A survey of the Cambridge Structural Database (Groom & Allen, 2014) revealed two more occurrences of the title compound, both crystallized in the C2/c space group. In the paper by Mednikov et al. (1987) the homonuclear Pd cluster is reported as a co-former, together with a trinuclear Pd cluster [Pd3(CO)3(PPh3)4], here as well the Pd cluster is found onto a twofold axis and superposition of both molecular entities reveals similar features, right up to similar orientations of the tri­phenyl­phosphines.

The second occurrence is however much more inter­esting as the structure of Feltham et al. (1985) shows remarkable similarities with the reported structure, not only with respect to the molecular conformation – the r.m.s. deviation between the two structures is 0.757 Å for all atoms, and 0.356 Å when omitting the phenyl rings – but also with respect to the overall crystal packing. Closer inspection of the unit-cell parameters, listed below, reveals that for both structures only the a axis differs significantly by more than 2 Å (2.297 Å):

a = 27.254 (9), b = 16.016 (6), c = 17.938 (7) Å, β = 105.92 (2)°, V = 7530.0 Å3, 120 K (title compound);

a = 24.957 (5), b = 16.138 (3), c = 17.758 (3) Å, β = 103.47 (2)°, V = 6955.4 Å3, RT, (Feltham et al., 1985).

While the Feltham et al. (1985) structure contains a total of 400 Å3 of voids distributed over six sites (pore sizes from 5–32 Å3), none of these is big enough to host even small solvent molecules, characterizing this structure as solvent-free. Gradual loss of solvent molecules is believed to provoke a transformation from the solvent-rich title compound to the desolvated structure reported by Feltham et al. (1985). The reported problems during crystal harvesting of the latter structure (see section 4) tends to support this hypothesis. The transformation itself appears to occur in a sequential process where two types of solvent cavities gradually lose their solvent molecules, leading to a contraction of the a axis. The first affected cavities are the 61 Å3 voids treated by SQUEEZE in the current structure, followed by the cavity hosting the loosely trapped THF molecule (289 Å3). After correcting for the inter­stitial voids observed in the contracted structure, the volume loss during the transformation is in complete agreement with the solvent loss in both cavities.

Fig. 2 shows the packing overlay by pairwise fitting of the Pd atoms of the reported structure and the structure of Feltham et al. (1985) (all Pd atoms within one unit cell were considered); evaporation of the THF molecules and small rearrangements of the homonuclear cluster allows the transformation of the solvated structure into the solvent-free analogue to be completed. This transformation only involves one dimension and a projection along the a axis of the superimposed unit cells reveals practically fully overlapped molecules, even when considering the orientation of the phenyl rings.

Synthesis and crystallization top

The synthesis of the title compound was an attempt to obtain mixed Au–Pd complexes in a one-step reaction. Through a THF solution of [Pd(PtBu3)2] and [Au(PPh3)Cl] carbon monoxide gas was passed and the solid material left after evaporation of the solvent was characterized by NMR and IR. One intense IR band at 1870 cm−1 indicated the formation of a complex with CO ligands. 31P NMR showed two signals at 28.1 and 97.2 p.p.m. with a 4:1 ratio, which indicate the presence of two types of phosphines, while the 1H NMR indicated the presence of both tri­phenyl­phosphine and tri-tert-butyl­phosphine. Dissolution of the solid in a THF/MeOH mixture yielded red crystals which were suitable for X-ray diffraction. Rather than a mixed Au–Pd species, the crystals contained a homonuclear Pd complex.

Previously the synthesis of the title compound was reported as the reduction of an oxygen-free CH2Cl2 solution of [Pd(NO2)2(PPh3)3] under CO. Crystals were formed upon cooling after addition of CO-saturated hexane and were reported to decompose rapidly and could finally be measured at room temperature in a CO-filled sealed capillary (Feltham et al., 1985). The homonuclear Pd4 cluster can also be synthesized by the reaction of [Pd2(dba)3] and three equivalents of PPh3 under CO (Willocq et al., 2011).

Refinement details top

Crystal data and structure refinement details are summarized in Table 3. Data were collected on a MAR345 image plate, using Mo Kα radiation generated on a Rigaku UltraX 18S generator (Zr filter). The reflections were integrated by marHKL; the data were not corrected for absorption, but the data collection mode with high redundancy, partially takes the absorption phenomena into account. (111 images, ΔΦ = 2°, 21617 reflections measured for 4740 independent reflections). H atoms were placed at calculated positions with isotropic temperature factors fixed at 1.2Ueq of the parent atom.

Computing details top

Data collection: mar345 (Klein, 1998); cell refinement: marHKL (Klein & Bartels, 2000); data reduction: marHKL (Klein & Bartels, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: Mercury (Macrae et al., 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. ORTEP representation of the title compound, showing displacement ellipsoids drawn at the 50% probability level. [Symmetry code: (a) −x, y, −z + 1/2.] Only the symmetry-unique THF solvent molecule is shown.
[Figure 2] Fig. 2. Packing overlay of the title compound measured at 120 K and the solvent-free structure of Feltham et al. (1985) measured at room temperature, obtained by pairwise fitting of all Pd atoms of the four molecules in the unit cell. The projection along the b axis reveals that, upon evaporation of the solvent molecules, the unit cell contracts, while keeping the global packing arrangement. Phenyl rings have been omitted for clarity.
Pentakis(µ-carbonyl-κ2C:C)tetrakis(triphenylphosphane-κP)tetrapalladium(5 Pd—Pd) tetrahydrofuran disolvate top
Crystal data top
[Pd4(CO)5(C18H15P)4]·2C4H8OF(000) = 3544
Mr = 1758.93Dx = 1.552 Mg m−3
Monoclinic, C2/cMo Kα radiation, λ = 0.71069 Å
a = 27.254 (9) ÅCell parameters from 4740 reflections
b = 16.016 (6) Åθ = 2.6–22.2°
c = 17.938 (7) ŵ = 1.08 mm−1
β = 105.92 (2)°T = 120 K
V = 7530 (5) Å3Platelets, red
Z = 40.18 × 0.12 × 0.05 mm
Data collection top
MAR345 image plate
diffractometer		3938 reflections with I > 2σ(I)
Radiation source: Rigaku UltraX 18 rotating anodeRint = 0.037
Zr filter monochromatorθmax = 22.2°, θmin = 2.5°
111 images, ΔΦ 2° scansh = −28→28
9236 measured reflectionsk = −17→17
4739 independent reflectionsl = −19→19
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.035H-atom parameters constrained
wR(F2) = 0.086 w = 1/[σ2(Fo2) + (0.0201P)2 + 36.9627P]
where P = (Fo2 + 2Fc2)/3
S = 1.03(Δ/σ)max = 0.001
4739 reflectionsΔρmax = 0.54 e Å−3
453 parametersΔρmin = −0.53 e Å−3
Crystal data top
[Pd4(CO)5(C18H15P)4]·2C4H8OV = 7530 (5) Å3
Mr = 1758.93Z = 4
Monoclinic, C2/cMo Kα radiation
a = 27.254 (9) ŵ = 1.08 mm−1
b = 16.016 (6) ÅT = 120 K
c = 17.938 (7) Å0.18 × 0.12 × 0.05 mm
β = 105.92 (2)°
Data collection top
MAR345 image plate
diffractometer		3938 reflections with I > 2σ(I)
9236 measured reflectionsRint = 0.037
4739 independent reflectionsθmax = 22.2°
Refinement top
R[F2 > 2σ(F2)] = 0.0350 restraints
wR(F2) = 0.086H-atom parameters constrained
S = 1.03 w = 1/[σ2(Fo2) + (0.0201P)2 + 36.9627P]
where P = (Fo2 + 2Fc2)/3
4739 reflectionsΔρmax = 0.54 e Å−3
453 parametersΔρmin = −0.53 e Å−3
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Pd10.00088 (2)0.70651 (2)0.16201 (2)0.01857 (13)
Pd2−0.05342 (2)0.59762 (2)0.22629 (2)0.01713 (13)
C10.0757 (2)0.6757 (3)0.1897 (3)0.0248 (13)
O10.11225 (15)0.6829 (2)0.1692 (2)0.0345 (9)
C2−0.0735 (2)0.6741 (3)0.1236 (3)0.0239 (12)
O2−0.10823 (14)0.6805 (2)0.0691 (2)0.0333 (9)
C30.00000.5003 (5)0.25000.0231 (17)
O30.00000.4268 (3)0.25000.0320 (13)
P3−0.00131 (5)0.82666 (8)0.09097 (7)0.0185 (3)
C40.06148 (19)0.8732 (3)0.1019 (3)0.0180 (11)
C50.0797 (2)0.8963 (3)0.0400 (3)0.0235 (12)
H50.05790.8915−0.01130.028*
C60.1284 (2)0.9258 (3)0.0510 (3)0.0275 (13)
H60.14050.94010.00780.033*
C70.1599 (2)0.9346 (4)0.1258 (3)0.0328 (14)
H70.19370.95480.13400.039*
C80.1422 (2)0.9140 (4)0.1878 (3)0.0365 (15)
H80.16360.92110.23900.044*
C90.0937 (2)0.8833 (3)0.1764 (3)0.0281 (13)
H90.08190.86860.21990.034*
C10−0.02718 (19)0.8146 (3)−0.0143 (3)0.0208 (12)
C11−0.0615 (2)0.8691 (3)−0.0601 (3)0.0262 (13)
H11−0.07410.9150−0.03720.031*
C12−0.0777 (2)0.8572 (4)−0.1398 (3)0.0346 (15)
H12−0.10240.8936−0.17140.041*
C13−0.0577 (2)0.7919 (4)−0.1732 (3)0.0373 (15)
H13−0.06780.7850−0.22790.045*
C14−0.0234 (2)0.7371 (4)−0.1274 (3)0.0373 (15)
H14−0.01000.6924−0.15060.045*
C15−0.0085 (2)0.7470 (3)−0.0478 (3)0.0280 (13)
H150.01430.7082−0.01610.034*
C16−0.03973 (19)0.9103 (3)0.1160 (3)0.0199 (12)
C17−0.0907 (2)0.8940 (3)0.1112 (3)0.0253 (13)
H17−0.10500.84100.09390.030*
C18−0.1208 (2)0.9551 (4)0.1318 (3)0.0317 (14)
H18−0.15560.94360.12750.038*
C19−0.1010 (2)1.0321 (3)0.1581 (3)0.0327 (15)
H19−0.12161.07340.17280.039*
C20−0.0505 (2)1.0477 (4)0.1628 (3)0.0309 (14)
H20−0.03641.10080.18020.037*
C21−0.0199 (2)0.9878 (3)0.1425 (3)0.0258 (13)
H210.01490.99980.14680.031*
P4−0.12826 (5)0.52022 (8)0.19235 (7)0.0191 (3)
C22−0.12432 (19)0.4330 (3)0.1291 (3)0.0233 (12)
C23−0.1279 (2)0.3498 (3)0.1471 (3)0.0314 (14)
H23−0.13290.33440.19560.038*
C24−0.1241 (2)0.2883 (4)0.0939 (4)0.0433 (16)
H24−0.12590.23120.10720.052*
C25−0.1178 (2)0.3084 (4)0.0231 (4)0.0373 (15)
H25−0.11600.2660−0.01310.045*
C26−0.1141 (3)0.3903 (4)0.0058 (4)0.0475 (17)
H26−0.10960.4052−0.04310.057*
C27−0.1170 (2)0.4521 (4)0.0578 (3)0.0419 (16)
H27−0.11390.50880.04440.050*
C28−0.14892 (18)0.4741 (3)0.2725 (3)0.0195 (12)
C29−0.1977 (2)0.4841 (4)0.2804 (3)0.0312 (14)
H29−0.22230.51500.24260.037*
C30−0.2109 (2)0.4494 (4)0.3431 (3)0.0359 (15)
H30−0.24410.45830.34910.043*
C31−0.1761 (2)0.4022 (3)0.3967 (3)0.0323 (14)
H31−0.18560.37650.43840.039*
C32−0.1277 (2)0.3926 (4)0.3896 (3)0.0411 (16)
H32−0.10340.36040.42660.049*
C33−0.1139 (2)0.4299 (4)0.3281 (3)0.0349 (15)
H33−0.07980.42470.32460.042*
C34−0.18558 (19)0.5748 (3)0.1361 (3)0.0232 (12)
C35−0.1923 (2)0.6592 (4)0.1488 (3)0.0359 (15)
H35−0.16630.68810.18610.043*
C36−0.2352 (2)0.7020 (4)0.1092 (4)0.0501 (18)
H36−0.23900.75940.11970.060*
C37−0.2727 (3)0.6609 (5)0.0542 (4)0.057 (2)
H37−0.30240.69020.02630.069*
C38−0.2673 (2)0.5785 (5)0.0398 (4)0.053 (2)
H38−0.29330.55060.00160.064*
C39−0.2241 (2)0.5345 (4)0.0806 (3)0.0374 (15)
H39−0.22090.47690.07040.045*
O1000.2944 (2)0.6292 (4)0.1655 (3)0.0822 (18)
C1010.2603 (3)0.6561 (5)0.0954 (5)0.079 (3)
H10A0.23030.61850.08050.095*
H10B0.27730.65620.05330.095*
C1020.2439 (3)0.7435 (5)0.1096 (4)0.063 (2)
H10C0.26750.78590.09890.076*
H10D0.20880.75550.07770.076*
C1030.2467 (3)0.7403 (5)0.1944 (4)0.069 (2)
H10E0.25410.79620.21850.082*
H10F0.21430.71940.20240.082*
C1040.2894 (3)0.6812 (5)0.2274 (4)0.063 (2)
H10G0.32150.71230.24970.076*
H10H0.28180.64710.26890.076*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pd10.0184 (2)0.0189 (2)0.0177 (2)−0.00139 (17)0.00377 (16)0.00374 (17)
Pd20.0165 (2)0.0166 (2)0.0186 (2)−0.00199 (16)0.00526 (16)0.00040 (17)
C10.035 (4)0.020 (3)0.017 (3)0.002 (3)0.002 (3)0.000 (2)
O10.030 (2)0.044 (3)0.035 (2)0.0032 (19)0.0176 (19)0.0124 (19)
C20.032 (3)0.014 (3)0.029 (3)−0.001 (2)0.014 (3)0.004 (2)
O20.028 (2)0.038 (2)0.026 (2)−0.0103 (18)−0.0057 (19)0.0121 (18)
C30.021 (4)0.026 (5)0.024 (4)0.0000.008 (3)0.000
O30.021 (3)0.025 (3)0.048 (4)0.0000.006 (2)0.000
P30.0200 (7)0.0193 (7)0.0157 (7)−0.0018 (6)0.0038 (5)0.0031 (6)
C40.023 (3)0.012 (3)0.019 (3)0.002 (2)0.005 (2)0.002 (2)
C50.026 (3)0.022 (3)0.022 (3)−0.004 (2)0.006 (2)0.004 (2)
C60.029 (3)0.032 (3)0.023 (3)−0.002 (3)0.010 (2)0.006 (3)
C70.027 (3)0.040 (4)0.033 (3)−0.006 (3)0.010 (3)0.001 (3)
C80.029 (4)0.052 (4)0.025 (3)−0.012 (3)0.003 (3)−0.001 (3)
C90.029 (3)0.040 (3)0.016 (3)−0.009 (3)0.006 (2)0.002 (3)
C100.021 (3)0.025 (3)0.017 (3)−0.007 (2)0.006 (2)0.004 (2)
C110.031 (3)0.022 (3)0.023 (3)−0.005 (2)0.003 (2)0.002 (2)
C120.037 (4)0.033 (3)0.027 (3)−0.008 (3)−0.001 (3)0.007 (3)
C130.054 (4)0.034 (4)0.025 (3)−0.023 (3)0.014 (3)−0.009 (3)
C140.045 (4)0.033 (4)0.036 (4)−0.016 (3)0.015 (3)−0.014 (3)
C150.027 (3)0.032 (3)0.027 (3)−0.003 (3)0.010 (2)−0.004 (3)
C160.025 (3)0.020 (3)0.013 (3)0.001 (2)0.002 (2)0.003 (2)
C170.028 (3)0.029 (3)0.017 (3)−0.003 (3)0.003 (2)0.000 (2)
C180.027 (3)0.051 (4)0.018 (3)0.009 (3)0.006 (2)0.008 (3)
C190.055 (4)0.029 (4)0.014 (3)0.014 (3)0.009 (3)0.005 (3)
C200.039 (4)0.031 (3)0.022 (3)0.007 (3)0.007 (3)0.002 (3)
C210.028 (3)0.031 (3)0.018 (3)0.002 (3)0.006 (2)0.001 (3)
P40.0187 (7)0.0196 (7)0.0192 (7)−0.0035 (6)0.0051 (6)0.0010 (6)
C220.021 (3)0.020 (3)0.030 (3)−0.007 (2)0.007 (2)−0.005 (2)
C230.027 (3)0.035 (4)0.032 (3)0.001 (3)0.008 (3)−0.003 (3)
C240.046 (4)0.022 (3)0.059 (4)−0.004 (3)0.011 (3)−0.014 (3)
C250.028 (3)0.036 (4)0.049 (4)0.002 (3)0.011 (3)−0.021 (3)
C260.069 (5)0.040 (4)0.042 (4)−0.009 (3)0.029 (3)−0.009 (3)
C270.071 (5)0.024 (3)0.040 (4)−0.009 (3)0.032 (3)−0.006 (3)
C280.021 (3)0.019 (3)0.019 (3)−0.006 (2)0.006 (2)0.002 (2)
C290.026 (3)0.042 (4)0.026 (3)−0.002 (3)0.007 (2)0.008 (3)
C300.026 (3)0.049 (4)0.037 (3)−0.010 (3)0.015 (3)0.003 (3)
C310.039 (4)0.036 (3)0.022 (3)−0.008 (3)0.008 (3)0.001 (3)
C320.034 (4)0.052 (4)0.039 (4)0.016 (3)0.012 (3)0.020 (3)
C330.021 (3)0.054 (4)0.034 (3)0.012 (3)0.015 (3)0.015 (3)
C340.015 (3)0.029 (3)0.028 (3)−0.005 (2)0.011 (2)0.015 (3)
C350.031 (3)0.048 (4)0.026 (3)0.013 (3)0.003 (3)0.009 (3)
C360.048 (4)0.056 (4)0.047 (4)0.028 (4)0.014 (4)0.018 (4)
C370.032 (4)0.085 (6)0.053 (5)0.017 (4)0.009 (3)0.040 (4)
C380.022 (4)0.088 (6)0.037 (4)−0.015 (4)−0.011 (3)0.033 (4)
C390.028 (3)0.044 (4)0.035 (3)−0.017 (3)0.000 (3)0.014 (3)
O1000.061 (4)0.110 (5)0.081 (4)0.038 (3)0.031 (3)0.018 (4)
C1010.094 (7)0.081 (6)0.062 (5)−0.012 (5)0.019 (5)0.002 (5)
C1020.051 (5)0.062 (5)0.068 (5)−0.002 (4)0.004 (4)0.006 (4)
C1030.057 (5)0.090 (6)0.062 (5)0.015 (4)0.022 (4)0.006 (5)
C1040.049 (5)0.082 (6)0.056 (5)0.005 (4)0.011 (4)0.018 (4)
Geometric parameters (Å, º) top
Pd1—C22.021 (6)C20—H200.9500
Pd1—C12.022 (6)C21—H210.9500
Pd1—P32.2998 (15)P4—C221.821 (5)
Pd1—Pd22.7381 (8)P4—C341.832 (5)
Pd1—Pd2i2.7446 (9)P4—C281.837 (5)
Pd1—Pd1i3.1704 (14)C22—C231.380 (8)
Pd2—C32.095 (6)C22—C271.383 (7)
Pd2—C22.154 (5)C23—C241.395 (8)
Pd2—C1i2.169 (6)C23—H230.9500
Pd2—P42.3208 (15)C24—C251.365 (9)
Pd2—Pd1i2.7446 (9)C24—H240.9500
Pd2—Pd2i2.8006 (12)C25—C261.358 (8)
C1—O11.159 (6)C25—H250.9500
C1—Pd2i2.169 (6)C26—C271.377 (8)
C2—O21.164 (6)C26—H260.9500
C3—O31.178 (9)C27—H270.9500
C3—Pd2i2.095 (6)C28—C331.373 (7)
P3—C41.827 (5)C28—C291.384 (7)
P3—C161.830 (5)C29—C301.388 (8)
P3—C101.836 (5)C29—H290.9500
C4—C51.385 (7)C30—C311.377 (8)
C4—C91.392 (7)C30—H300.9500
C5—C61.373 (7)C31—C321.369 (8)
C5—H50.9500C31—H310.9500
C6—C71.387 (7)C32—C331.394 (8)
C6—H60.9500C32—H320.9500
C7—C81.368 (8)C33—H330.9500
C7—H70.9500C34—C351.391 (8)
C8—C91.372 (8)C34—C391.391 (7)
C8—H80.9500C35—C361.375 (8)
C9—H90.9500C35—H350.9500
C10—C111.374 (7)C36—C371.377 (10)
C10—C151.401 (7)C36—H360.9500
C11—C121.390 (7)C37—C381.361 (10)
C11—H110.9500C37—H370.9500
C12—C131.388 (8)C38—C391.395 (9)
C12—H120.9500C38—H380.9500
C13—C141.379 (8)C39—H390.9500
C13—H130.9500O100—C1011.410 (9)
C14—C151.382 (7)O100—C1041.425 (9)
C14—H140.9500C101—C1021.512 (11)
C15—H150.9500C101—H10A0.9900
C16—C211.385 (7)C101—H10B0.9900
C16—C171.394 (7)C102—C1031.503 (10)
C17—C181.389 (8)C102—H10C0.9900
C17—H170.9500C102—H10D0.9900
C18—C191.376 (8)C103—C1041.490 (10)
C18—H180.9500C103—H10E0.9900
C19—C201.379 (8)C103—H10F0.9900
C19—H190.9500C104—H10G0.9900
C20—C211.384 (7)C104—H10H0.9900
C2—Pd1—C1150.4 (2)C17—C18—H18119.4
C2—Pd1—P398.89 (15)C18—C19—C20118.3 (5)
C1—Pd1—P3102.22 (16)C18—C19—H19120.9
C2—Pd1—Pd251.16 (15)C20—C19—H19120.9
C1—Pd1—Pd2111.46 (15)C19—C20—C21121.4 (5)
P3—Pd1—Pd2146.24 (4)C19—C20—H20119.3
C2—Pd1—Pd2i111.07 (15)C21—C20—H20119.3
C1—Pd1—Pd2i51.44 (15)C20—C21—C16120.4 (5)
P3—Pd1—Pd2i149.92 (4)C20—C21—H21119.8
Pd2—Pd1—Pd2i61.43 (3)C16—C21—H21119.8
C2—Pd1—Pd1i92.97 (15)C22—P4—C34102.1 (2)
C1—Pd1—Pd1i92.60 (15)C22—P4—C28105.2 (2)
P3—Pd1—Pd1i123.13 (4)C34—P4—C28103.0 (2)
Pd2—Pd1—Pd1i54.768 (18)C22—P4—Pd2112.06 (17)
Pd2i—Pd1—Pd1i54.58 (2)C34—P4—Pd2116.44 (17)
C3—Pd2—C2126.58 (14)C28—P4—Pd2116.45 (16)
C3—Pd2—C1i126.77 (14)C23—C22—C27117.8 (5)
C2—Pd2—C1i102.29 (19)C23—C22—P4125.1 (4)
C3—Pd2—P499.66 (15)C27—C22—P4117.0 (4)
C2—Pd2—P494.64 (15)C22—C23—C24120.0 (6)
C1i—Pd2—P495.57 (15)C22—C23—H23120.0
C3—Pd2—Pd197.67 (12)C24—C23—H23120.0
C2—Pd2—Pd146.94 (15)C25—C24—C23121.4 (6)
C1i—Pd2—Pd1102.24 (15)C25—C24—H24119.3
P4—Pd2—Pd1140.12 (4)C23—C24—H24119.3
C3—Pd2—Pd1i97.47 (12)C26—C25—C24118.5 (6)
C2—Pd2—Pd1i102.83 (14)C26—C25—H25120.8
C1i—Pd2—Pd1i46.81 (15)C24—C25—H25120.8
P4—Pd2—Pd1i140.88 (4)C25—C26—C27121.2 (6)
Pd1—Pd2—Pd1i70.66 (3)C25—C26—H26119.4
C3—Pd2—Pd2i48.05 (15)C27—C26—H26119.4
C2—Pd2—Pd2i104.98 (15)C26—C27—C22121.2 (6)
C1i—Pd2—Pd2i104.73 (15)C26—C27—H27119.4
P4—Pd2—Pd2i147.71 (4)C22—C27—H27119.4
Pd1—Pd2—Pd2i59.40 (2)C33—C28—C29118.8 (5)
Pd1i—Pd2—Pd2i59.171 (19)C33—C28—P4118.3 (4)
O1—C1—Pd1142.6 (4)C29—C28—P4122.8 (4)
O1—C1—Pd2i135.0 (4)C28—C29—C30120.4 (5)
Pd1—C1—Pd2i81.7 (2)C28—C29—H29119.8
O2—C2—Pd1140.6 (4)C30—C29—H29119.8
O2—C2—Pd2136.5 (4)C31—C30—C29120.2 (5)
Pd1—C2—Pd281.9 (2)C31—C30—H30119.9
O3—C3—Pd2138.05 (15)C29—C30—H30119.9
O3—C3—Pd2i138.05 (15)C32—C31—C30119.6 (5)
Pd2—C3—Pd2i83.9 (3)C32—C31—H31120.2
C4—P3—C16104.9 (2)C30—C31—H31120.2
C4—P3—C10103.7 (2)C31—C32—C33120.1 (5)
C16—P3—C10104.2 (2)C31—C32—H32119.9
C4—P3—Pd1113.63 (16)C33—C32—H32119.9
C16—P3—Pd1113.95 (16)C28—C33—C32120.7 (5)
C10—P3—Pd1115.24 (17)C28—C33—H33119.6
C5—C4—C9118.0 (5)C32—C33—H33119.6
C5—C4—P3123.6 (4)C35—C34—C39117.4 (5)
C9—C4—P3118.4 (4)C35—C34—P4120.2 (4)
C6—C5—C4121.4 (5)C39—C34—P4122.4 (4)
C6—C5—H5119.3C36—C35—C34122.1 (6)
C4—C5—H5119.3C36—C35—H35119.0
C5—C6—C7119.4 (5)C34—C35—H35119.0
C5—C6—H6120.3C35—C36—C37119.5 (7)
C7—C6—H6120.3C35—C36—H36120.3
C8—C7—C6120.0 (5)C37—C36—H36120.3
C8—C7—H7120.0C38—C37—C36120.2 (6)
C6—C7—H7120.0C38—C37—H37119.9
C7—C8—C9120.4 (5)C36—C37—H37119.9
C7—C8—H8119.8C37—C38—C39120.6 (6)
C9—C8—H8119.8C37—C38—H38119.7
C8—C9—C4120.8 (5)C39—C38—H38119.7
C8—C9—H9119.6C34—C39—C38120.3 (6)
C4—C9—H9119.6C34—C39—H39119.8
C11—C10—C15120.1 (5)C38—C39—H39119.8
C11—C10—P3123.7 (4)C101—O100—C104109.6 (6)
C15—C10—P3116.1 (4)O100—C101—C102106.6 (7)
C10—C11—C12120.1 (5)O100—C101—H10A110.4
C10—C11—H11120.0C102—C101—H10A110.4
C12—C11—H11120.0O100—C101—H10B110.4
C13—C12—C11119.7 (5)C102—C101—H10B110.4
C13—C12—H12120.1H10A—C101—H10B108.6
C11—C12—H12120.1C103—C102—C101101.7 (6)
C14—C13—C12120.3 (5)C103—C102—H10C111.4
C14—C13—H13119.8C101—C102—H10C111.4
C12—C13—H13119.8C103—C102—H10D111.4
C13—C14—C15120.1 (6)C101—C102—H10D111.4
C13—C14—H14119.9H10C—C102—H10D109.3
C15—C14—H14119.9C104—C103—C102104.0 (6)
C14—C15—C10119.6 (5)C104—C103—H10E111.0
C14—C15—H15120.2C102—C103—H10E111.0
C10—C15—H15120.2C104—C103—H10F111.0
C21—C16—C17118.4 (5)C102—C103—H10F111.0
C21—C16—P3123.0 (4)H10E—C103—H10F109.0
C17—C16—P3118.5 (4)O100—C104—C103107.0 (6)
C18—C17—C16120.2 (5)O100—C104—H10G110.3
C18—C17—H17119.9C103—C104—H10G110.3
C16—C17—H17119.9O100—C104—H10H110.3
C19—C18—C17121.2 (5)C103—C104—H10H110.3
C19—C18—H18119.4H10G—C104—H10H108.6
C16—P3—C4—C5−105.5 (4)C34—P4—C22—C2763.2 (5)
C10—P3—C4—C53.6 (5)C28—P4—C22—C27170.4 (4)
Pd1—P3—C4—C5129.5 (4)Pd2—P4—C22—C27−62.1 (5)
C16—P3—C4—C977.1 (4)C27—C22—C23—C240.0 (8)
C10—P3—C4—C9−173.9 (4)P4—C22—C23—C24−179.8 (4)
Pd1—P3—C4—C9−48.0 (4)C22—C23—C24—C25−1.2 (9)
C9—C4—C5—C61.9 (8)C23—C24—C25—C261.3 (9)
P3—C4—C5—C6−175.5 (4)C24—C25—C26—C27−0.3 (10)
C4—C5—C6—C7−1.5 (8)C25—C26—C27—C22−0.9 (10)
C5—C6—C7—C8−0.1 (9)C23—C22—C27—C261.0 (9)
C6—C7—C8—C91.2 (9)P4—C22—C27—C26−179.2 (5)
C7—C8—C9—C4−0.7 (9)C22—P4—C28—C3375.3 (5)
C5—C4—C9—C8−0.8 (8)C34—P4—C28—C33−178.1 (4)
P3—C4—C9—C8176.7 (4)Pd2—P4—C28—C33−49.4 (5)
C4—P3—C10—C11−99.7 (5)C22—P4—C28—C29−106.7 (5)
C16—P3—C10—C119.8 (5)C34—P4—C28—C29−0.1 (5)
Pd1—P3—C10—C11135.4 (4)Pd2—P4—C28—C29128.6 (4)
C4—P3—C10—C1577.9 (4)C33—C28—C29—C30−0.5 (8)
C16—P3—C10—C15−172.5 (4)P4—C28—C29—C30−178.6 (4)
Pd1—P3—C10—C15−46.9 (4)C28—C29—C30—C31−2.3 (9)
C15—C10—C11—C120.0 (8)C29—C30—C31—C322.7 (9)
P3—C10—C11—C12177.5 (4)C30—C31—C32—C33−0.4 (9)
C10—C11—C12—C13−2.3 (8)C29—C28—C33—C322.8 (9)
C11—C12—C13—C142.5 (8)P4—C28—C33—C32−179.1 (5)
C12—C13—C14—C15−0.3 (8)C31—C32—C33—C28−2.4 (10)
C13—C14—C15—C10−2.1 (8)C22—P4—C34—C35−156.5 (4)
C11—C10—C15—C142.2 (8)C28—P4—C34—C3594.6 (4)
P3—C10—C15—C14−175.5 (4)Pd2—P4—C34—C35−34.1 (5)
C4—P3—C16—C21−4.3 (5)C22—P4—C34—C3924.4 (5)
C10—P3—C16—C21−113.0 (4)C28—P4—C34—C39−84.5 (5)
Pd1—P3—C16—C21120.6 (4)Pd2—P4—C34—C39146.8 (4)
C4—P3—C16—C17178.4 (4)C39—C34—C35—C360.7 (8)
C10—P3—C16—C1769.7 (4)P4—C34—C35—C36−178.5 (5)
Pd1—P3—C16—C17−56.7 (4)C34—C35—C36—C37−1.0 (9)
C21—C16—C17—C180.9 (7)C35—C36—C37—C380.5 (10)
P3—C16—C17—C18178.3 (4)C36—C37—C38—C390.3 (10)
C16—C17—C18—C19−0.9 (7)C35—C34—C39—C380.2 (8)
C17—C18—C19—C200.9 (7)P4—C34—C39—C38179.3 (4)
C18—C19—C20—C21−0.8 (7)C37—C38—C39—C34−0.6 (9)
C19—C20—C21—C160.8 (7)C104—O100—C101—C10216.7 (9)
C17—C16—C21—C20−0.8 (7)O100—C101—C102—C103−30.5 (8)
P3—C16—C21—C20−178.1 (4)C101—C102—C103—C10432.2 (8)
C34—P4—C22—C23−117.1 (5)C101—O100—C104—C1034.4 (9)
C28—P4—C22—C23−9.8 (5)C102—C103—C104—O100−23.6 (8)
Pd2—P4—C22—C23117.6 (4)
Symmetry code: (i) −x, y, −z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C19—H19···O100ii0.952.433.282 (8)149
Symmetry code: (ii) x−1/2, y+1/2, z.
Selected bond lengths (Å) top
Pd1—Pd22.7381 (8)Pd2—P42.3208 (15)
Pd1—Pd2i2.7446 (9)Pd2—Pd1i2.7446 (9)
Pd1—Pd1i3.1704 (14)Pd2—Pd2i2.8006 (12)
Symmetry code: (i) −x, y, −z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C19—H19···O100ii0.952.433.282 (8)149
Symmetry code: (ii) x−1/2, y+1/2, z.

Experimental details

Crystal data
Chemical formula[Pd4(CO)5(C18H15P)4]·2C4H8O
Mr1758.93
Crystal system, space groupMonoclinic, C2/c
Temperature (K)120
a, b, c (Å)27.254 (9), 16.016 (6), 17.938 (7)
β (°) 105.92 (2)
V (Å3)7530 (5)
Z4
Radiation typeMo Kα
µ (mm−1)1.08
Crystal size (mm)0.18 × 0.12 × 0.05
Data collection
DiffractometerMAR345 image plate
Absorption correction–
No. of measured, independent and
observed [I > 2σ(I)] reflections		9236, 4739, 3938
Rint0.037
θmax (°)22.2
(sin θ/λ)max (Å−1)0.532
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.086, 1.03
No. of reflections4739
No. of parameters453
H-atom treatmentH-atom parameters constrained
w = 1/[σ2(Fo2) + (0.0201P)2 + 36.9627P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å−3)0.54, −0.53

Computer programs: mar345 (Klein, 1998), marHKL (Klein & Bartels, 2000), SHELXS97 (Sheldrick, 2008), SHELXL2014 (Sheldrick, 2015), Mercury (Macrae et al., 2008) and PLATON (Spek, 2009).

 

Acknowledgements

The authors thank the Fonds de la Recherche dans l'Industrie et l'Agriculture (FRIA) for the research fellowship allotted to CW, and the Belgian National Fund for Scientific Research (FNRS) for financial support.

References

First citationEdwards, J. K., Freakley, S. J., Lewis, R. J., Pritchard, J. C. & Hutchings, G. J. (2015). Catal. Today, 248, 3–9.  Web of Science CrossRef CAS Google Scholar
 First citationFeltham, R. D., Elbaze, G., Ortega, R., Eck, C. & Dubrawski, J. (1985). Inorg. Chem. 24, 1503–1510.  CSD CrossRef CAS Web of Science Google Scholar
 First citationGroom, C. R. & Allen, F. H. (2014). Angew. Chem. Int. Ed. 53, 662–671.  Web of Science CSD CrossRef CAS Google Scholar
 First citationHermans, S., Deffernez, A. & Devillers, M. (2010). Catal. Today, 157, 77–82.  Web of Science CrossRef CAS Google Scholar
 First citationHermans, S., Deffernez, A. & Devillers, M. (2011). Appl. Catal. Gen. 395, 19–27.  Web of Science CrossRef CAS Google Scholar
 First citationHermans, S. & Devillers, M. (2005). Catal. Lett. 99, 55–64.  Web of Science CrossRef CAS Google Scholar
 First citationIto, L. N., Felicissimo, A. M. P. & Pignolet, L. H. (1991). Inorg. Chem. 30, 988–994.  CSD CrossRef CAS Web of Science Google Scholar
 First citationKlein, C. (1998). mar345. X-ray Research GmbH, Norderstedt, Germany.  Google Scholar
 First citationKlein, C. & Bartels, K. (2000). marHKL. X-ray Research GmbH, Norderstedt, Germany.  Google Scholar
 First citationMacrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
 First citationMednikov, E. G., Eremenko, L. A., Slovokhotov, Y. L., Struchkov, Y. T. & Gubin, S. P. (1987). Koord. Khim. 13, 979.  Google Scholar
 First citationPaalanen, P., Weckhuysen, B. M. & Sankar, M. (2013). Catal. Sci. Technol. 3, 2869–2880.  Web of Science CrossRef CAS Google Scholar
 First citationQuintilio, W., Sotelo, A. & Felicissimo, A. M. P. (1994). Spectrosc. Lett. 27, 605–611.  CrossRef CAS Web of Science Google Scholar
 First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationSheldrick, G. M. (2015). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
 First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationSpek, A. L. (2015). Acta Cryst. C71, 9–18.  Web of Science CrossRef IUCr Journals Google Scholar
 First citationVilla, A., Wang, D., Su, D. S. & Prati, L. (2015). Catal. Sci. Technol. 5, 55–68.  Web of Science CrossRef CAS Google Scholar
 First citationWillocq, C., Tinant, B., Aubriet, F., Carré, V., Devillers, M. & Hermans, S. (2011). Inorg. Chim. Acta, 373, 233–242.  Web of Science CSD CrossRef CAS Google Scholar

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Journal logoCRYSTALLOGRAPHIC
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ISSN: 2056-9890
Volume 72| Part 2| February 2016| Pages 120-123
doi:10.1107/S205698901502441X
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