metal-organic compounds
Dichlorido(3,5-dimethyl-1H-pyrazole)[(3,5-dimethyl-1H-pyrazol-1-yl)(o-tolyl)methanone]palladium(II)
aDepartment of Chemistry, University of Johannesburg, PO Box 524, Auckland Park, Johannesburg 2006, South Africa
*Correspondence e-mail: gjkruger@uj.ac.za
In the title compound, [PdCl2(C5H8N2)(C12H12N2O)], the Pd atom adopts a slightly distorted trans-PdCl2N2 square-planar arrangement. The different Pd—N bond lengths can be related to the the electron-withdrawing effect of the o-toluoyl group on the substituted pyrazole ligand. The complex crystallizes as centrosymmetric hydrogen-bonded dimers through N—H⋯Cl linkages.
Related literature
For related literature, see: Mukherjee (2000); Komeda et al. (2000); Li et al. (2002); Guzei et al. (2003); Guzei et al. (2005); Ojwach et al. (2005); Spencer et al. (2006); Allen (2002).
Experimental
Crystal data
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Refinement
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Data collection: SMART-NT (Bruker, 1998); cell SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 1999), PLATON (Spek, 2003) and publCIF (Westrip, 2008).
Supporting information
https://doi.org/10.1107/S1600536807066627/hb2672sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807066627/hb2672Isup2.hkl
To a solution of [PdCl2(NCMe)2] (0.10 g, 0.47 mmol) in dichloromethane (30 ml), was added (3,5-dimethyl-pyrazol-1-yl)-o-toluoyl-methanone (0.06 g, 0.23 mmol). The formation of an orange-yellow solution was observed and the reaction mixture was stirred at room temperature for 24 h. The solution was then concentrated to 15 ml and an equal amount of hexane was added and kept at -4 °C for 3 days to yield yellow crystals suitable for X-ray analysis. Yield = 0.08 g, 59%. IR (Nujol): ν (C=O) = 1699. 1H NMR (CDCl3): δ 9.50 (s, 1H, N—H), 7.54 (m, 4H, o-toluoyl), 6.13 (s, 1H, 4-pz, o-toluoyl), 5.74 (s, 1H, 4-pz), 2.94 (s, 3H, o-toluoyl), 2.56 (s, 3H, 5-CH3, o-toluoyl), 2.35 (s, 3H, 3-CH3, o-toluoyl), 2.31 (s, 3H, 5-CH3,), 2.21 (s, 3H, 3-CH3). 13C{1H} NMR: δ 169.4, 157.4, 137.6, 133.3, 131.5, 128.4, 118.6, 106.5, 33.1, 32.4, 30.1.
The H atoms were geometrically positioned and refined in the riding-model approximation, with C—H = 0.93–0.96 Å, N—H = 0.86 Å, and Uiso(H) = 1.2Ueq(C) or 1.5Ueq(N). The highest peak in the final difference map is 0.87 Å from Cl1 and the deepest hole is 0.88 Å from N11.
Pyrazole and pyrazolyl ligands have been used to form N-donor metal complexes with interesting catalytic applications (Mukherjee, 2000) and as mimics for imidazole coordination in metalloenzymes (Komeda et al., 2000). Catalytic behaviour of such N-donor metal complexes, in particular, depends on the nature of substituents on the pyrazolyl ligands. The introduction of dicarbonylbenzene linkers (Guzei et al., 2003) to bis(pyrazole)palladium complexes (Li et al., 2002), for instance, improves the activity of these complexes as ethylene polymerization catalysts. The presence of carbonyl functional groups in palladium complexes, however, reduces their stability as catalysts. We initially attributed the reduced stability to the effect of two carbonyl groups on the N-donor ability of the pyrazolyl ligands. In an attempt to improve the stability of the palladium catalysts, monocarbonylbenzene units were attached to pyrazolyl units to prepare the bis(pyrazolylcarbonylbenzene)palladium dichloride. Surprisingly, with (3,5-dimethyl-pyrazol-1-yl)-o-toluoyl-methanone as a ligand during complexation with PdCl2, we isolated the title compound, (I), a mixed ligand palladium complex, containing (3,5-dimethyl-pyrazol-1-yl)-o-toluoyl-methanone and 3,5-dimethylpyrazole as ligands. The formation of compound I appears to occur via partial hydrolysis of one of the (3,5-dimethyl-pyrazol-1-yl)-o-toluoyl-methanone ligands, presumably by traces of water in the reaction mixture.
Compound (I) displays square planar geometry around the palladium atom, with the two different pyrazolyl ligands ((3,5-dimethyl-pyrazol-1-yl)-o-toluoyl-methanone and 3,5-dimethylpyrazole) bonding trans to the metal centre via N atoms (Fig. 1). The slight distortion of the square planar configuration around the palladium atom can be seen in the differences in bond angles involving palladium (Table 1) and the deviations from the least-squares plane through the central five atoms [Pd1 = -0.0116 (12) Å, Cl1 = -0.0684 (12) Å, Cl2 = -0.0665 (12) Å, N11 = 0.0754 (17) Å, N21 = 0.0711 (16) Å], with the biggest deviations being observed for the nitrogen atoms. The pyrazolyl rings of the coordinating ligands are roughly perpendicular to this central plane, with interplanar angles of 86.66 (12)° and 68.13 (14)° respectively. The Pd—Cl bond distances in (I) are similar to Pd—Cl distances in related complexes (e.g. Spencer et al., 2006) and consistent with the average of 2.33 (4)Å calculated for 2151 Pd—Cl distances in 1306 complexes reported to the Cambridge Structural Database (CSD, Version 5.26, updated May 2005; Allen 2002). One interesting feature of (I) is the significant difference of 0.053 Å in the Pd—N bond distances for the two ligands, illustrating the electron-withdrawing effect of the o-toluoyl-methanone substituent on the pyrazolyl ligand.
Intermolecular hydrogen bonding is responsible for the formation of centrosymmetric dimers through N—H···Cl linkages [Figure 2, Table 2]. In contrast to previous observations (Li et al., 2002), the hydrogen bonding in (I) has no effect on the bond order: we observed two virtually identical Pd—Cl bond lengths, although only Cl1 was involved in a N—H···Cl hydrogen bond.
For related literature, see: Mukherjee (2000); Komeda et al. (2000); Li et al. (2002); Guzei et al. (2003); Guzei et al. (2005); Ojwach et al. (2005); Spencer et al. (2006); Allen (2002).
Data collection: SMART-NT (Bruker, 1998); cell
SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 1999), PLATON (Spek, 2003) and publCIF (Westrip, 2008).[PdCl2(C5H8N2)(C12H12N2O)] | F(000) = 1968 |
Mr = 487.70 | Dx = 1.585 Mg m−3 |
Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 2686 reflections |
a = 15.908 (3) Å | θ = 2.2–26.0° |
b = 15.479 (3) Å | µ = 1.18 mm−1 |
c = 16.602 (3) Å | T = 293 K |
V = 4088.0 (12) Å3 | Block, yellow |
Z = 8 | 0.32 × 0.28 × 0.15 mm |
Bruker SMART CCD diffractometer | 4023 independent reflections |
Radiation source: fine-focus sealed tube | 2686 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.056 |
φ and ω scans | θmax = 26.0°, θmin = 2.2° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2004) | h = −19→19 |
Tmin = 0.703, Tmax = 0.843 | k = −18→19 |
43509 measured reflections | l = −20→20 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.040 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.114 | H-atom parameters constrained |
S = 1.08 | w = 1/[σ2(Fo2) + (0.0425P)2 + 9.9045P] where P = (Fo2 + 2Fc2)/3 |
4023 reflections | (Δ/σ)max = 0.001 |
240 parameters | Δρmax = 1.09 e Å−3 |
0 restraints | Δρmin = −0.49 e Å−3 |
[PdCl2(C5H8N2)(C12H12N2O)] | V = 4088.0 (12) Å3 |
Mr = 487.70 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 15.908 (3) Å | µ = 1.18 mm−1 |
b = 15.479 (3) Å | T = 293 K |
c = 16.602 (3) Å | 0.32 × 0.28 × 0.15 mm |
Bruker SMART CCD diffractometer | 4023 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2004) | 2686 reflections with I > 2σ(I) |
Tmin = 0.703, Tmax = 0.843 | Rint = 0.056 |
43509 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.114 | H-atom parameters constrained |
S = 1.08 | Δρmax = 1.09 e Å−3 |
4023 reflections | Δρmin = −0.49 e Å−3 |
240 parameters |
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. Atoms 'Deviations (Å)' Pd1 - 0.0116 (12) Cl1 - 0.0684 (12) Cl2 - 0.0665 (12) N11 0.0754 (17) N21 0.0711 (16) Atoms 'Deviations (Å)' N11 - 0.0012 (32) N12 0.0016 (33) C11 - 0.0010 (51) C12 - 0.0021 (49) C13 - 0.0038 (56) C14 0.0023 (42) C15 0.0042 (45) Atoms 'Deviations (Å)' N21 0.0327 (35) N22 - 0.0225 (38) C21 - 0.0159 (65) C22 0.0319 (54) C23 0.0057 (55) C24 - 0.0040 (49) C25 - 0.0279 (46) Atoms 'Deviations (Å)' C32 0.0353 (49) C31 0.0478 (44) C33 - 0.0055 (54) C34 - 0.0356 (52) C35 - 0.0064 (49) C36 0.0160 (51) C37 0.0075 (42) C26 - 0.0592 (38) 'Plane 1' 'Plane 2' 'Interplanar Angle (°)' Square 'Ring 1' 86.66 (12) Square 'Ring 2' 68.13 (14) 'Ring 2' 'Ring 3' 55.98 (25) |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
C11 | 0.1260 (3) | −0.2107 (3) | 0.4805 (3) | 0.0544 (13) | |
C12 | 0.1495 (4) | −0.2290 (3) | 0.4037 (4) | 0.0588 (14) | |
H12 | 0.1646 | −0.2829 | 0.3836 | 0.071* | |
C13 | 0.1468 (4) | −0.1521 (3) | 0.3608 (3) | 0.0551 (13) | |
C14 | 0.1168 (4) | −0.2659 (4) | 0.5543 (4) | 0.087 (2) | |
H14A | 0.1677 | −0.2977 | 0.5631 | 0.130* | |
H14B | 0.0709 | −0.3054 | 0.5470 | 0.130* | |
H14C | 0.1057 | −0.2297 | 0.6001 | 0.130* | |
C15 | 0.1668 (5) | −0.1341 (4) | 0.2743 (4) | 0.095 (2) | |
H15A | 0.1195 | −0.1067 | 0.2491 | 0.142* | |
H15B | 0.1791 | −0.1874 | 0.2472 | 0.142* | |
H15C | 0.2148 | −0.0966 | 0.2712 | 0.142* | |
C21 | 0.1020 (4) | 0.3084 (3) | 0.3533 (4) | 0.0726 (18) | |
C22 | 0.1203 (4) | 0.3102 (4) | 0.4313 (4) | 0.0668 (16) | |
H22 | 0.1299 | 0.3593 | 0.4623 | 0.080* | |
C23 | 0.1226 (4) | 0.2247 (3) | 0.4582 (3) | 0.0580 (14) | |
C24 | 0.0921 (6) | 0.3799 (4) | 0.2929 (5) | 0.115 (3) | |
H24A | 0.0338 | 0.3952 | 0.2886 | 0.173* | |
H24B | 0.1122 | 0.3608 | 0.2414 | 0.173* | |
H24C | 0.1238 | 0.4293 | 0.3100 | 0.173* | |
C25 | 0.1364 (5) | 0.1919 (4) | 0.5424 (4) | 0.095 (2) | |
H25A | 0.0850 | 0.1676 | 0.5626 | 0.142* | |
H25B | 0.1536 | 0.2388 | 0.5764 | 0.142* | |
H25C | 0.1793 | 0.1483 | 0.5419 | 0.142* | |
C26 | 0.0658 (4) | 0.1895 (4) | 0.2552 (3) | 0.0679 (16) | |
C32 | 0.2068 (4) | 0.1314 (4) | 0.2339 (4) | 0.0711 (17) | |
H32 | 0.2248 | 0.1655 | 0.2767 | 0.085* | |
C31 | 0.1223 (3) | 0.1290 (3) | 0.2129 (3) | 0.0495 (12) | |
C33 | 0.2646 (4) | 0.0820 (5) | 0.1902 (4) | 0.086 (2) | |
H33 | 0.3213 | 0.0829 | 0.2038 | 0.103* | |
C34 | 0.2379 (5) | 0.0334 (5) | 0.1288 (4) | 0.085 (2) | |
H34 | 0.2763 | 0.0012 | 0.0992 | 0.102* | |
C35 | 0.1495 (5) | 0.0305 (4) | 0.1079 (3) | 0.0738 (18) | |
H35 | 0.1312 | −0.0047 | 0.0659 | 0.089* | |
C36 | 0.0945 (4) | 0.0783 (4) | 0.1488 (3) | 0.0687 (17) | |
C37 | 0.0019 (5) | 0.0762 (5) | 0.1242 (4) | 0.093 (2) | |
H37B | −0.0105 | 0.1254 | 0.0910 | 0.140* | |
H37C | −0.0328 | 0.0776 | 0.1715 | 0.140* | |
H37A | −0.0092 | 0.0242 | 0.0945 | 0.140* | |
N11 | 0.1224 (3) | −0.0881 (3) | 0.4099 (2) | 0.0491 (10) | |
N12 | 0.1103 (3) | −0.1256 (3) | 0.4824 (2) | 0.0521 (10) | |
H12A | 0.0943 | −0.0982 | 0.5248 | 0.062* | |
N21 | 0.1115 (2) | 0.1715 (2) | 0.3970 (2) | 0.0425 (9) | |
N22 | 0.0961 (3) | 0.2227 (3) | 0.3322 (3) | 0.0650 (13) | |
O1 | 0.0029 (4) | 0.2206 (3) | 0.2275 (3) | 0.1102 (19) | |
Cl1 | 0.25848 (9) | 0.04521 (9) | 0.42155 (10) | 0.0660 (4) | |
Cl2 | −0.02466 (9) | 0.02924 (9) | 0.36848 (9) | 0.0614 (4) | |
Pd1 | 0.11619 (2) | 0.03965 (2) | 0.39821 (2) | 0.04292 (14) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C11 | 0.058 (3) | 0.038 (3) | 0.068 (3) | 0.002 (2) | −0.001 (3) | 0.012 (2) |
C12 | 0.064 (3) | 0.033 (3) | 0.080 (4) | −0.004 (2) | 0.005 (3) | −0.006 (3) |
C13 | 0.070 (4) | 0.041 (3) | 0.054 (3) | 0.002 (3) | 0.014 (3) | −0.009 (2) |
C14 | 0.110 (6) | 0.063 (4) | 0.088 (5) | 0.006 (4) | 0.000 (4) | 0.026 (4) |
C15 | 0.156 (7) | 0.071 (4) | 0.058 (4) | −0.007 (5) | 0.025 (4) | −0.009 (3) |
C21 | 0.106 (5) | 0.037 (3) | 0.074 (4) | 0.011 (3) | 0.004 (4) | 0.001 (3) |
C22 | 0.082 (4) | 0.046 (3) | 0.072 (4) | 0.003 (3) | −0.001 (3) | −0.022 (3) |
C23 | 0.077 (4) | 0.043 (3) | 0.053 (3) | 0.008 (3) | −0.002 (3) | −0.011 (2) |
C24 | 0.182 (9) | 0.053 (4) | 0.111 (6) | 0.023 (5) | 0.007 (6) | 0.022 (4) |
C25 | 0.162 (8) | 0.072 (4) | 0.051 (4) | 0.014 (5) | −0.011 (4) | −0.012 (3) |
C26 | 0.090 (5) | 0.057 (4) | 0.056 (3) | 0.022 (3) | −0.004 (3) | 0.006 (3) |
C32 | 0.078 (4) | 0.082 (4) | 0.054 (3) | −0.003 (4) | 0.002 (3) | 0.011 (3) |
C31 | 0.066 (3) | 0.043 (3) | 0.040 (2) | 0.006 (3) | 0.004 (2) | 0.008 (2) |
C33 | 0.070 (5) | 0.109 (6) | 0.078 (5) | 0.017 (4) | 0.018 (4) | 0.005 (4) |
C34 | 0.099 (6) | 0.089 (5) | 0.069 (4) | 0.030 (4) | 0.028 (4) | 0.008 (4) |
C35 | 0.117 (6) | 0.056 (4) | 0.049 (3) | 0.016 (4) | 0.013 (3) | 0.001 (3) |
C36 | 0.108 (5) | 0.053 (3) | 0.045 (3) | 0.000 (3) | 0.010 (3) | 0.008 (3) |
C37 | 0.093 (5) | 0.096 (5) | 0.090 (5) | −0.014 (4) | −0.029 (4) | 0.000 (4) |
N11 | 0.065 (3) | 0.041 (2) | 0.041 (2) | −0.002 (2) | −0.004 (2) | 0.0020 (17) |
N12 | 0.065 (3) | 0.044 (2) | 0.047 (2) | 0.006 (2) | 0.003 (2) | 0.0008 (19) |
N21 | 0.055 (2) | 0.034 (2) | 0.039 (2) | 0.0076 (17) | −0.0045 (19) | −0.0001 (17) |
N22 | 0.107 (4) | 0.039 (2) | 0.049 (3) | 0.010 (2) | −0.006 (2) | −0.003 (2) |
O1 | 0.126 (4) | 0.119 (4) | 0.085 (3) | 0.064 (4) | −0.030 (3) | −0.013 (3) |
Cl1 | 0.0588 (8) | 0.0530 (8) | 0.0862 (10) | −0.0017 (7) | −0.0193 (7) | 0.0089 (7) |
Cl2 | 0.0509 (7) | 0.0671 (9) | 0.0661 (8) | 0.0038 (7) | −0.0010 (6) | −0.0147 (7) |
Pd1 | 0.0545 (2) | 0.0340 (2) | 0.0403 (2) | 0.00246 (17) | −0.00455 (17) | −0.00125 (16) |
C11—N12 | 1.342 (6) | C25—H25C | 0.9600 |
C11—C12 | 1.358 (8) | C26—O1 | 1.202 (7) |
C11—C14 | 1.501 (8) | C26—N22 | 1.459 (7) |
C12—C13 | 1.388 (7) | C26—C31 | 1.475 (7) |
C12—H12 | 0.9300 | C32—C31 | 1.389 (8) |
C13—N11 | 1.340 (6) | C32—C33 | 1.398 (8) |
C13—C15 | 1.498 (8) | C32—H32 | 0.9300 |
C14—H14A | 0.9600 | C31—C36 | 1.394 (8) |
C14—H14B | 0.9600 | C33—C34 | 1.336 (10) |
C14—H14C | 0.9600 | C33—H33 | 0.9300 |
C15—H15A | 0.9600 | C34—C35 | 1.449 (10) |
C15—H15B | 0.9600 | C34—H34 | 0.9300 |
C15—H15C | 0.9600 | C35—C36 | 1.333 (8) |
C21—C22 | 1.328 (9) | C35—H35 | 0.9300 |
C21—N22 | 1.377 (7) | C36—C37 | 1.529 (9) |
C21—C24 | 1.501 (8) | C37—H37B | 0.9600 |
C22—C23 | 1.398 (8) | C37—H37C | 0.9600 |
C22—H22 | 0.9300 | C37—H37A | 0.9600 |
C23—N21 | 1.319 (6) | N11—N12 | 1.350 (5) |
C23—C25 | 1.503 (8) | Pd1—N11 | 1.989 (4) |
C24—H24A | 0.9600 | Pd1—N21 | 2.042 (4) |
C24—H24B | 0.9600 | Pd1—Cl1 | 2.2981 (15) |
C24—H24C | 0.9600 | Pd1—Cl2 | 2.3001 (15) |
C25—H25A | 0.9600 | N12—H12A | 0.8600 |
C25—H25B | 0.9600 | N21—N22 | 1.359 (5) |
N12—C11—C12 | 106.2 (5) | N22—C26—C31 | 116.0 (5) |
N12—C11—C14 | 121.3 (5) | C31—C32—C33 | 119.4 (6) |
C12—C11—C14 | 132.5 (5) | C31—C32—H32 | 120.3 |
C11—C12—C13 | 107.1 (5) | C33—C32—H32 | 120.3 |
C11—C12—H12 | 126.5 | C32—C31—C36 | 120.9 (5) |
C13—C12—H12 | 126.5 | C32—C31—C26 | 117.0 (5) |
N11—C13—C12 | 109.3 (5) | C36—C31—C26 | 121.7 (5) |
N11—C13—C15 | 120.5 (5) | C34—C33—C32 | 119.6 (7) |
C12—C13—C15 | 130.1 (5) | C34—C33—H33 | 120.2 |
C11—C14—H14A | 109.5 | C32—C33—H33 | 120.2 |
C11—C14—H14B | 109.5 | C33—C34—C35 | 120.6 (6) |
H14A—C14—H14B | 109.5 | C33—C34—H34 | 119.7 |
C11—C14—H14C | 109.5 | C35—C34—H34 | 119.7 |
H14A—C14—H14C | 109.5 | C36—C35—C34 | 119.8 (6) |
H14B—C14—H14C | 109.5 | C36—C35—H35 | 120.1 |
C13—C15—H15A | 109.5 | C34—C35—H35 | 120.1 |
C13—C15—H15B | 109.5 | C35—C36—C31 | 119.6 (7) |
H15A—C15—H15B | 109.5 | C35—C36—C37 | 118.9 (6) |
C13—C15—H15C | 109.5 | C31—C36—C37 | 121.5 (6) |
H15A—C15—H15C | 109.5 | C36—C37—H37B | 109.5 |
H15B—C15—H15C | 109.5 | C36—C37—H37C | 109.5 |
C22—C21—N22 | 106.5 (5) | H37B—C37—H37C | 109.5 |
C22—C21—C24 | 131.2 (6) | C36—C37—H37A | 109.5 |
N22—C21—C24 | 122.2 (6) | H37B—C37—H37A | 109.5 |
C21—C22—C23 | 107.3 (5) | H37C—C37—H37A | 109.5 |
C21—C22—H22 | 126.3 | C13—N11—N12 | 105.4 (4) |
C23—C22—H22 | 126.3 | C13—N11—Pd1 | 133.6 (3) |
N21—C23—C22 | 110.0 (5) | N12—N11—Pd1 | 120.5 (3) |
N21—C23—C25 | 121.6 (5) | C11—N12—N11 | 112.0 (4) |
C22—C23—C25 | 128.4 (5) | C11—N12—H12A | 124.0 |
C21—C24—H24A | 109.5 | N11—N12—H12A | 124.0 |
C21—C24—H24B | 109.5 | C23—N21—N22 | 105.7 (4) |
H24A—C24—H24B | 109.5 | C23—N21—Pd1 | 127.7 (3) |
C21—C24—H24C | 109.5 | N22—N21—Pd1 | 126.6 (3) |
H24A—C24—H24C | 109.5 | N21—N22—C21 | 110.4 (4) |
H24B—C24—H24C | 109.5 | N21—N22—C26 | 123.3 (4) |
C23—C25—H25A | 109.5 | C21—N22—C26 | 125.8 (5) |
C23—C25—H25B | 109.5 | N11—Pd1—N21 | 174.88 (15) |
H25A—C25—H25B | 109.5 | N11—Pd1—Cl1 | 88.39 (13) |
C23—C25—H25C | 109.5 | N21—Pd1—Cl1 | 90.02 (12) |
H25A—C25—H25C | 109.5 | N11—Pd1—Cl2 | 89.98 (13) |
H25B—C25—H25C | 109.5 | N21—Pd1—Cl2 | 91.84 (12) |
O1—C26—N22 | 117.9 (5) | Cl1—Pd1—Cl2 | 176.71 (5) |
O1—C26—C31 | 125.4 (6) | ||
N12—C11—C12—C13 | −0.2 (6) | C14—C11—N12—N11 | 180.0 (5) |
C14—C11—C12—C13 | −179.9 (6) | C13—N11—N12—C11 | −0.1 (6) |
C11—C12—C13—N11 | 0.1 (7) | Pd1—N11—N12—C11 | −173.1 (3) |
C11—C12—C13—C15 | 179.5 (7) | C22—C23—N21—N22 | −4.3 (6) |
N22—C21—C22—C23 | −2.1 (7) | C25—C23—N21—N22 | 176.5 (6) |
C24—C21—C22—C23 | −179.4 (7) | C22—C23—N21—Pd1 | 175.7 (4) |
C21—C22—C23—N21 | 4.1 (7) | C25—C23—N21—Pd1 | −3.5 (8) |
C21—C22—C23—C25 | −176.7 (7) | C23—N21—N22—C21 | 3.0 (6) |
C33—C32—C31—C36 | −0.2 (8) | Pd1—N21—N22—C21 | −177.0 (4) |
C33—C32—C31—C26 | −173.4 (6) | C23—N21—N22—C26 | −168.9 (5) |
O1—C26—C31—C32 | 149.9 (7) | Pd1—N21—N22—C26 | 11.1 (7) |
N22—C26—C31—C32 | −21.1 (7) | C22—C21—N22—N21 | −0.5 (7) |
O1—C26—C31—C36 | −23.3 (10) | C24—C21—N22—N21 | 177.0 (6) |
N22—C26—C31—C36 | 165.7 (5) | C22—C21—N22—C26 | 171.1 (6) |
C31—C32—C33—C34 | 0.2 (10) | C24—C21—N22—C26 | −11.3 (11) |
C32—C33—C34—C35 | −0.9 (11) | O1—C26—N22—N21 | 125.6 (7) |
C33—C34—C35—C36 | 1.7 (10) | C31—C26—N22—N21 | −62.7 (7) |
C34—C35—C36—C31 | −1.7 (9) | O1—C26—N22—C21 | −45.1 (10) |
C34—C35—C36—C37 | 178.3 (6) | C31—C26—N22—C21 | 126.6 (6) |
C32—C31—C36—C35 | 1.0 (8) | C13—N11—Pd1—Cl1 | −79.2 (5) |
C26—C31—C36—C35 | 173.9 (5) | N12—N11—Pd1—Cl1 | 91.4 (3) |
C32—C31—C36—C37 | −179.0 (5) | C13—N11—Pd1—Cl2 | 97.9 (5) |
C26—C31—C36—C37 | −6.1 (8) | N12—N11—Pd1—Cl2 | −91.5 (3) |
C12—C13—N11—N12 | 0.0 (6) | C23—N21—Pd1—Cl1 | −68.9 (4) |
C15—C13—N11—N12 | −179.5 (6) | N22—N21—Pd1—Cl1 | 111.1 (4) |
C12—C13—N11—Pd1 | 171.6 (4) | C23—N21—Pd1—Cl2 | 113.8 (4) |
C15—C13—N11—Pd1 | −7.9 (9) | N22—N21—Pd1—Cl2 | −66.2 (4) |
C12—C11—N12—N11 | 0.2 (6) |
D—H···A | D—H | H···A | D···A | D—H···A |
N12—H12A···Cl2i | 0.86 | 2.35 | 3.194 (4) | 169 |
Symmetry code: (i) −x, −y, −z+1. |
Experimental details
Crystal data | |
Chemical formula | [PdCl2(C5H8N2)(C12H12N2O)] |
Mr | 487.70 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 293 |
a, b, c (Å) | 15.908 (3), 15.479 (3), 16.602 (3) |
V (Å3) | 4088.0 (12) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 1.18 |
Crystal size (mm) | 0.32 × 0.28 × 0.15 |
Data collection | |
Diffractometer | Bruker SMART CCD |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2004) |
Tmin, Tmax | 0.703, 0.843 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 43509, 4023, 2686 |
Rint | 0.056 |
(sin θ/λ)max (Å−1) | 0.617 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.114, 1.08 |
No. of reflections | 4023 |
No. of parameters | 240 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.09, −0.49 |
Computer programs: SMART-NT (Bruker, 1998), SAINT-Plus (Bruker, 1999), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2006), WinGX (Farrugia, 1999), PLATON (Spek, 2003) and publCIF (Westrip, 2008).
Pd1—N11 | 1.989 (4) | Pd1—Cl1 | 2.2981 (15) |
Pd1—N21 | 2.042 (4) | Pd1—Cl2 | 2.3001 (15) |
N11—Pd1—N21 | 174.88 (15) | N11—Pd1—Cl2 | 89.98 (13) |
N11—Pd1—Cl1 | 88.39 (13) | N21—Pd1—Cl2 | 91.84 (12) |
N21—Pd1—Cl1 | 90.02 (12) | Cl1—Pd1—Cl2 | 176.71 (5) |
D—H···A | D—H | H···A | D···A | D—H···A |
N12—H12A···Cl2i | 0.86 | 2.35 | 3.194 (4) | 169 |
Symmetry code: (i) −x, −y, −z+1. |
Acknowledgements
The authors thank the National Research Foundation (NRF South Africa) and the National Research Foundation – Department of Science and Technology, (South Africa) Centre of Excellence in Catalysis (c*change) for financial support, and the University of the Witwatersrand for the use of the diffractometers in the Jan Boeyens Structural Chemistry Laboratory.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Pyrazole and pyrazolyl ligands have been used to form N-donor metal complexes with interesting catalytic applications (Mukherjee, 2000) and as mimics for imidazole coordination in metalloenzymes (Komeda et al., 2000). Catalytic behaviour of such N-donor metal complexes, in particular, depends on the nature of substituents on the pyrazolyl ligands. The introduction of dicarbonylbenzene linkers (Guzei et al., 2003) to bis(pyrazole)palladium complexes (Li et al., 2002), for instance, improves the activity of these complexes as ethylene polymerization catalysts. The presence of carbonyl functional groups in palladium complexes, however, reduces their stability as catalysts. We initially attributed the reduced stability to the effect of two carbonyl groups on the N-donor ability of the pyrazolyl ligands. In an attempt to improve the stability of the palladium catalysts, monocarbonylbenzene units were attached to pyrazolyl units to prepare the bis(pyrazolylcarbonylbenzene)palladium dichloride. Surprisingly, with (3,5-dimethyl-pyrazol-1-yl)-o-toluoyl-methanone as a ligand during complexation with PdCl2, we isolated the title compound, (I), a mixed ligand palladium complex, containing (3,5-dimethyl-pyrazol-1-yl)-o-toluoyl-methanone and 3,5-dimethylpyrazole as ligands. The formation of compound I appears to occur via partial hydrolysis of one of the (3,5-dimethyl-pyrazol-1-yl)-o-toluoyl-methanone ligands, presumably by traces of water in the reaction mixture.
Compound (I) displays square planar geometry around the palladium atom, with the two different pyrazolyl ligands ((3,5-dimethyl-pyrazol-1-yl)-o-toluoyl-methanone and 3,5-dimethylpyrazole) bonding trans to the metal centre via N atoms (Fig. 1). The slight distortion of the square planar configuration around the palladium atom can be seen in the differences in bond angles involving palladium (Table 1) and the deviations from the least-squares plane through the central five atoms [Pd1 = -0.0116 (12) Å, Cl1 = -0.0684 (12) Å, Cl2 = -0.0665 (12) Å, N11 = 0.0754 (17) Å, N21 = 0.0711 (16) Å], with the biggest deviations being observed for the nitrogen atoms. The pyrazolyl rings of the coordinating ligands are roughly perpendicular to this central plane, with interplanar angles of 86.66 (12)° and 68.13 (14)° respectively. The Pd—Cl bond distances in (I) are similar to Pd—Cl distances in related complexes (e.g. Spencer et al., 2006) and consistent with the average of 2.33 (4)Å calculated for 2151 Pd—Cl distances in 1306 complexes reported to the Cambridge Structural Database (CSD, Version 5.26, updated May 2005; Allen 2002). One interesting feature of (I) is the significant difference of 0.053 Å in the Pd—N bond distances for the two ligands, illustrating the electron-withdrawing effect of the o-toluoyl-methanone substituent on the pyrazolyl ligand.
Intermolecular hydrogen bonding is responsible for the formation of centrosymmetric dimers through N—H···Cl linkages [Figure 2, Table 2]. In contrast to previous observations (Li et al., 2002), the hydrogen bonding in (I) has no effect on the bond order: we observed two virtually identical Pd—Cl bond lengths, although only Cl1 was involved in a N—H···Cl hydrogen bond.