cis-Tetra­chloridobis(1H-imidazole-κN3)platinum(IV)

Bokach, N.A.; Kukushkin, V.Y.; Izotova, Y.A.; Usenko, N.I.; Haukka, M.

doi:10.1107/S1600536812013323

metal-organic compounds

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ISSN: 2056-9890

Volume 68| Part 5| May 2012| Pages m547-m548

doi:10.1107/S1600536812013323

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cis-Tetrachloridobis(1H-imidazole-κN³)platinum(IV)

Nadezhda A. Bokach,^a Vadim Yu. Kukushkin,^a Yulia A. Izotova,^a Natalia I. Usenko ^b ^* and Matti Haukka ^c

^aDepartment of Chemistry, Saint-Petersburg State University, Universitetsky Pr. 26, 198504 Stary Petergof, Russian Federation, ^bDepartment of Chemistry, Taras Shevchenko National University, 01601 Kiev, Ukraine, and ^cDepartment of Chemistry, University of Eastern Finland, PO Box 111, FI-80101 Joensuu, Finland
^*Correspondence e-mail: nusenko@univ.kiev.ua

(Received 11 March 2012; accepted 27 March 2012; online 4 April 2012)

In the title complex, cis-[PtCl₄(C₃H₄N₂)₂], the Pt^IV ion lies on a twofold rotation axis and is coordinated in a slightly distorted octahedral geometry. The dihedral angle between the imidazole rings is 69.9 (2)°. In the crystal, molecules are linked by N—H⋯Cl hydrogen bonds, forming a three-dimensional network.

Related literature

For applications of platinum species bearing N-bonded heterocycles, see: Ravera et al. (2011 ); Esmaeilbeig et al. (2011 ); Al-Shuneigat et al. (2010 ); Wheate et al. (2007 ); van Zutphen et al. (2006 ); Fritsky et al. (2000 ); Krämer & Fritsky (2000 ). For the synthesis of platinum complexes with N-heterocyclic ligands, see: Bokach, Kuznetsov et al. (2011 ); Kritchenkov et al. (2011 ); Bokach, Balova et al. (2011 ); Tskhovrebov et al. (2009 ); Luzyanin et al. (2009 ); Bokach et al. (2009 ). For related structures, see: Khripun et al. (2006 , 2007 ); Korte et al. (1981 ); Kuduk-Jaworska et al. (1988 ); Bayon et al. (1987 ); Yip et al. (1993 ); Chen et al. (2006 ); Gao et al. (2004 ); Garcia et al. (2000 ); Hao & Yu (2007 ); Huo et al. (2004 ). For bond-length data, see: Orpen et al. (1989 ).

Experimental

Crystal data

[PtCl₄(C₃H₄N₂)₂]
M_r = 473.05
Monoclinic, C 2/c
a = 7.7264 (4) Å
b = 11.8757 (6) Å
c = 12.9471 (5) Å
β = 93.332 (3)°
V = 1185.97 (10) Å³
Z = 4
Mo Kα radiation
μ = 12.70 mm⁻¹
T = 120 K
0.15 × 0.13 × 0.07 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997 ) T_min = 0.193, T_max = 0.411
7759 measured reflections
1362 independent reflections
1275 reflections with I > 2σ(I)
R_int = 0.037

Refinement

R[F² > 2σ(F²)] = 0.019
wR(F²) = 0.037
S = 1.05
1362 reflections
70 parameters
H-atom parameters constrained
Δρ_max = 0.68 e Å⁻³
Δρ_min = −0.73 e Å⁻³

Table 1
Selected bond lengths (Å)

Pt1—N1	2.046 (3)
Pt1—Cl2	2.3141 (8)
Pt1—Cl1	2.3193 (8)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2N⋯Cl1ⁱⁱ	0.98	2.66	3.355 (3)	128
N2—H2N⋯Cl2ⁱⁱ	0.98	2.70	3.320 (3)	122
N2—H2N⋯Cl1ⁱⁱⁱ	0.98	2.82	3.368 (3)	116
Symmetry codes: (ii) $[x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (iii) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ .

Data collection: COLLECT (Nonius, 2000 ); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812013323/lh5433sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812013323/lh5433Isup2.hkl

checkCIF report

Comment top

Platinum species, bearing N-bonded heterocycles (including, in particular, imidazoles) have drawn attention as efficient antitumor agents (Ravera et al., 2011; Esmaeilbeig et al., 2011; Al-Shuneigat et al., 2010; Wheate et al., 2007; van Zutphen et al., 2006). Within the framework of our projects the focus is on the synthesis of platinum complexes with N-heterocyclic ligands (Bokach, Kuznetsov et al., 2011; Kritchenkov et al., 2011; Bokach, Balova et al., 2011; Tskhovrebov et al., 2009; Luzyanin et al., 2009; Bokach et al., 2009; Krämer et al., 2000; Fritsky et al., 2000), the title compound (I) was synthesized and characterized by single-crystal X-ray diffraction.

In (I) the Pt^IV ion is in a slightly distorted octahedral coordination geometry formed by two N and four Cl atoms. Two imidazole ligands are in a cis orientation. The Pt—Cl bond distances are similar, within 3σ, to other Pt—Cl bond lengths [2.323 (38) Å] in platinum(IV) complexes (Orpen et al., 1989). The Pt—N distances are usual for platinum complexes bearing two cis-coordinated N-bonded heterocycles, e.g. 2.044 (3)–2.055 (5) Å in platinum(IV) complexes (Khripun et al., 2007; Khripun et al., 2006).

The title compound (1) represents the first example of the structurally characterized platinum complex having the neutral unsubstituted imidazole ligand and the second example of an imidazole Pt(IV) complex (Kuduk-Jaworska et al., 1988). The dihedral angle between the imidazole rings is 69.9 (2)°. The bond distances and angles in the heterocyclic ligands are in good agreement with those previously observed for imidazole ligands at platinum (Korte et al., 1981; Kuduk-Jaworska et al., 1988; Bayon et al., 1987; Yip et al., 1993) and other transition metal centers (for recent examples see Huo et al., 2004; Chen et al., 2006; Garcia et al., 2000; Hao et al., 2007; Gao et al., 2004). In the crystal, molecules are linked bt N—H···.Cl hydrogen bonds to form a three-dimensional network (Table 2).

Related literature top

For applications of platinum species bearing N-bonded heterocycles, see: Ravera et al. (2011); Esmaeilbeig et al. (2011); Al-Shuneigat et al. (2010); Wheate et al. (2007); van Zutphen et al. (2006); Fritsky et al. (2000); Krämer & Fritsky (2000). For the synthesis of platinum complexes with N-heterocyclic ligands, see: Bokach, Kuznetsov et al. (2011); Kritchenkov et al. (2011); Bokach, Balova et al. (2011); Tskhovrebov et al. (2009); Luzyanin et al. (2009); Bokach et al. (2009). For related structures, see: Khripun et al. (2006, 2007); Korte et al. (1981); Kuduk-Jaworska et al. (1988); Bayon et al. (1987); Yip et al. (1993); Chen et al. (2006); Gao et al. (2004); Garcia et al. (2000); Hao & Yu (2007); Huo et al. (2004); Orpen et al. (1989).

Experimental top

Complex (1) was synthesized by the reaction of cis-[PtCl₄(EtCN)₂] with 2 equivs of imidazole in CH₂Cl₂ solution at room temperature. The crystals suitable for X-ray crystallography were obtained from an acetone/toluene solution by a slow evaporation of the solvent at room temperature.

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

Fig. 1. The molecular structure of (I), with displacement ellipsoids drawn at the 40% probability level. Unlabled atoms are related by the symmetry operator (-x, y, -z+1/2).

cis-Tetrachloridobis(1H-imidazole-κN³)platinum(IV) top

Crystal data top

[PtCl₄(C₃H₄N₂)₂]	F(000) = 872
M_r = 473.05	D_x = 2.649 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 4469 reflections
a = 7.7264 (4) Å	θ = 1.0–27.5°
b = 11.8757 (6) Å	µ = 12.70 mm⁻¹
c = 12.9471 (5) Å	T = 120 K
β = 93.332 (3)°	Plate, yellow
V = 1185.97 (10) Å³	0.15 × 0.13 × 0.07 mm
Z = 4

Data collection top

Nonius KappaCCD diffractometer	1362 independent reflections
Radiation source: fine-focus sealed tube	1275 reflections with I > 2σ(I)
Horizontally mounted graphite crystal monochromator	R_int = 0.037
Detector resolution: 9 pixels mm^-1	θ_max = 27.5°, θ_min = 3.2°
ϕ scans and ω scans with κ offset	h = −9→10
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997)	k = −15→15
T_min = 0.193, T_max = 0.411	l = −16→14
7759 measured reflections

Refinement top

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)] = 0.019	Hydrogen site location: mixed
wR(F²) = 0.037	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0108P)² + 3.3813P] where P = (F_o² + 2F_c²)/3
1362 reflections	(Δ/σ)_max < 0.001
70 parameters	Δρ_max = 0.68 e Å⁻³
0 restraints	Δρ_min = −0.73 e Å⁻³

Crystal data top

[PtCl₄(C₃H₄N₂)₂]	V = 1185.97 (10) Å³
M_r = 473.05	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 7.7264 (4) Å	µ = 12.70 mm⁻¹
b = 11.8757 (6) Å	T = 120 K
c = 12.9471 (5) Å	0.15 × 0.13 × 0.07 mm
β = 93.332 (3)°

Data collection top

Nonius KappaCCD diffractometer	1362 independent reflections
Absorption correction: multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997)	1275 reflections with I > 2σ(I)
T_min = 0.193, T_max = 0.411	R_int = 0.037
7759 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.019	0 restraints
wR(F²) = 0.037	H-atom parameters constrained
S = 1.05	Δρ_max = 0.68 e Å⁻³
1362 reflections	Δρ_min = −0.73 e Å⁻³
70 parameters

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.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Pt1	0.0000	0.132240 (14)	0.2500	0.01672 (7)
Cl1	0.07166 (12)	−0.00761 (7)	0.37001 (7)	0.02527 (19)
Cl2	−0.28465 (11)	0.13451 (7)	0.29654 (7)	0.02696 (19)
N1	0.0594 (4)	0.2545 (2)	0.3576 (2)	0.0184 (6)
N2	0.1812 (4)	0.3987 (3)	0.4316 (2)	0.0292 (7)
H2N	0.2549	0.4662	0.4359	0.044*
C1	0.1675 (5)	0.3389 (3)	0.3449 (3)	0.0265 (8)
H1	0.2259	0.3543	0.2838	0.032*
C2	0.0790 (5)	0.3503 (3)	0.5026 (3)	0.0274 (8)
H2	0.0644	0.3754	0.5712	0.033*
C3	0.0036 (5)	0.2603 (3)	0.4555 (3)	0.0266 (8)
H3	−0.0747	0.2097	0.4852	0.032*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Pt1	0.01632 (10)	0.01756 (10)	0.01655 (10)	0.000	0.00311 (7)	0.000
Cl1	0.0301 (5)	0.0228 (4)	0.0226 (4)	−0.0022 (3)	−0.0010 (4)	0.0041 (3)
Cl2	0.0199 (4)	0.0313 (5)	0.0303 (5)	−0.0019 (3)	0.0074 (3)	0.0022 (4)
N1	0.0200 (15)	0.0182 (14)	0.0168 (14)	−0.0014 (11)	0.0002 (11)	−0.0001 (11)
N2	0.0340 (18)	0.0251 (15)	0.0287 (17)	−0.0063 (13)	0.0030 (14)	−0.0034 (13)
C1	0.028 (2)	0.0261 (18)	0.025 (2)	−0.0052 (15)	0.0041 (16)	−0.0030 (14)
C2	0.030 (2)	0.0280 (19)	0.0248 (19)	0.0004 (15)	0.0060 (16)	−0.0032 (15)
C3	0.028 (2)	0.0293 (19)	0.0236 (19)	0.0000 (15)	0.0072 (15)	−0.0002 (15)

Geometric parameters (Å, º) top

Pt1—N1ⁱ	2.046 (3)	N2—C1	1.327 (5)
Pt1—N1	2.046 (3)	N2—C2	1.372 (5)
Pt1—Cl2ⁱ	2.3141 (8)	N2—H2N	0.9830
Pt1—Cl2	2.3141 (8)	C1—H1	0.9500
Pt1—Cl1	2.3193 (8)	C2—C3	1.347 (5)
Pt1—Cl1ⁱ	2.3193 (8)	C2—H2	0.9500
N1—C1	1.321 (4)	C3—H3	0.9500
N1—C3	1.364 (4)

N1ⁱ—Pt1—N1	89.55 (15)	C1—N1—C3	108.3 (3)
N1ⁱ—Pt1—Cl2ⁱ	89.63 (8)	C1—N1—Pt1	124.9 (2)
N1—Pt1—Cl2ⁱ	89.43 (8)	C3—N1—Pt1	126.7 (2)
N1ⁱ—Pt1—Cl2	89.43 (8)	C1—N2—C2	108.8 (3)
N1—Pt1—Cl2	89.63 (8)	C1—N2—H2N	120.1
Cl2ⁱ—Pt1—Cl2	178.67 (4)	C2—N2—H2N	131.1
N1ⁱ—Pt1—Cl1	178.88 (8)	N1—C1—N2	108.7 (3)
N1—Pt1—Cl1	90.97 (8)	N1—C1—H1	125.7
Cl2ⁱ—Pt1—Cl1	89.38 (3)	N2—C1—H1	125.7
Cl2—Pt1—Cl1	91.57 (3)	C3—C2—N2	106.3 (3)
N1ⁱ—Pt1—Cl1ⁱ	90.97 (8)	C3—C2—H2	126.9
N1—Pt1—Cl1ⁱ	178.88 (8)	N2—C2—H2	126.9
Cl2ⁱ—Pt1—Cl1ⁱ	91.57 (3)	C2—C3—N1	108.0 (3)
Cl2—Pt1—Cl1ⁱ	89.38 (3)	C2—C3—H3	126.0
Cl1—Pt1—Cl1ⁱ	88.54 (4)	N1—C3—H3	126.0

Symmetry code: (i) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2N···Cl1ⁱⁱ	0.98	2.66	3.355 (3)	128
N2—H2N···Cl2ⁱⁱ	0.98	2.70	3.320 (3)	122
N2—H2N···Cl1ⁱⁱⁱ	0.98	2.82	3.368 (3)	116

Symmetry codes: (ii) x+1/2, y+1/2, z; (iii) −x+1/2, −y+1/2, −z+1.

Experimental details

Crystal data
Chemical formula	[PtCl₄(C₃H₄N₂)₂]
M_r	473.05
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	120
a, b, c (Å)	7.7264 (4), 11.8757 (6), 12.9471 (5)
β (°)	93.332 (3)
V (Å³)	1185.97 (10)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	12.70
Crystal size (mm)	0.15 × 0.13 × 0.07

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	Multi-scan (DENZO/SCALEPACK; Otwinowski & Minor, 1997)
T_min, T_max	0.193, 0.411
No. of measured, independent and observed [I > 2σ(I)] reflections	7759, 1362, 1275
R_int	0.037
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.019, 0.037, 1.05
No. of reflections	1362
No. of parameters	70
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.68, −0.73

Computer programs: COLLECT (Nonius, 2000), DENZO/SCALEPACK (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2008).

Selected geometric parameters (Å, º) top

Pt1—N1	2.046 (3)	Pt1—Cl1	2.3193 (8)
Pt1—Cl2	2.3141 (8)

N1ⁱ—Pt1—N1	89.55 (15)	Cl2—Pt1—Cl1	91.57 (3)
N1—Pt1—Cl2ⁱ	89.43 (8)	N1—Pt1—Cl1ⁱ	178.88 (8)
N1—Pt1—Cl2	89.63 (8)	Cl2—Pt1—Cl1ⁱ	89.38 (3)
Cl2ⁱ—Pt1—Cl2	178.67 (4)	Cl1—Pt1—Cl1ⁱ	88.54 (4)
N1—Pt1—Cl1	90.97 (8)

Symmetry code: (i) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2N···Cl1ⁱⁱ	0.98	2.66	3.355 (3)	128.3
N2—H2N···Cl2ⁱⁱ	0.98	2.70	3.320 (3)	121.5
N2—H2N···Cl1ⁱⁱⁱ	0.98	2.82	3.368 (3)	115.9

Symmetry codes: (ii) x+1/2, y+1/2, z; (iii) −x+1/2, −y+1/2, −z+1.

Acknowledgements

This work was supported by the Russian Fund for Basic Research (grant 11–03–90417) and the State Fund for Fundamental Research of Ukraine (grant No. F40.3/041). Financial support from the Visby Program through the Swedish Institute is gratefully acknowledged. Anatoly V. Khripun is thanked for experimental assistance.

References

Al-Shuneigat, J., Yu, J. Q., Beale, P., Fisher, K. & Huq, F. (2010). Med. Chem. 6, 321–328. Web of Science CAS PubMed Google Scholar
Bayon, J. C., Kolowich, J. B. & Rasmussen, P. G. (1987). Polyhedron, 6, 341–343. CAS Google Scholar
Bokach, N. A., Balova, I. A., Haukka, M. & Kukushkin, V. Yu. (2011). Organometallics, 30, 595–602. Web of Science CSD CrossRef CAS Google Scholar
Bokach, N. A., Kuznetsov, M. L., Haukka, M., Ovcharenko, V. I., Tretyakov, E. V. & Kukushkin, V. Yu. (2009). Organometallics, 28, 1406–1413. Web of Science CSD CrossRef CAS Google Scholar
Bokach, N. A., Kuznetsov, M. L. & Kukushkin, V. Yu. (2011). Coord. Chem. Rev. 255, 2946–2967. Web of Science CrossRef CAS Google Scholar
Brandenburg, K. (2008). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Chen, Y., Zhang, H., Wang, X., Huang, Ch., Cao, Y. & Sun, R. (2006). J. Solid State Chem. 179, 1674–1680. Web of Science CSD CrossRef CAS Google Scholar
Esmaeilbeig, A., Samouei, H., Abedanzadeh, S. & Amirghofran, Z. (2011). J. Organomet. Chem. 696, 3135–3142. Web of Science CSD CrossRef CAS Google Scholar
Fritsky, I. O., Ott, R. & Krämer, R. (2000). Angew. Chem. Int. Ed. 39, 3255–3258. CrossRef CAS Google Scholar
Gao, S., Liu, J.-W., Huo, L.-H., Zhao, H. & Ng, S. W. (2004). Acta Cryst. E60, m1329–m1330. Web of Science CSD CrossRef IUCr Journals Google Scholar
Garcia, R., Paulo, A., Domingos, A., Santos, I., Ortner, K. & Alberto, R. (2000). J. Am. Chem. Soc. 122, 11240–11241. Web of Science CSD CrossRef CAS Google Scholar
Hao, L.-J. & Yu, T.-L. (2007). Acta Cryst. E63, m2555. Web of Science CSD CrossRef IUCr Journals Google Scholar
Huo, L.-H., Gao, S., Zhao, H. & Ng, S. W. (2004). Acta Cryst. E60, m1747–m1749. Web of Science CSD CrossRef IUCr Journals Google Scholar
Khripun, A. V., Haukka, M. & Kukushkin, V. Yu. (2006). Russ. Chem. Bull. pp. 247–255. Web of Science CrossRef Google Scholar
Khripun, A. V., Kukushkin, V. Yu., Koldobskii, G. I. & Haukka, M. (2007). Inorg. Chem. Commun. 10, 250–254. Web of Science CSD CrossRef CAS Google Scholar
Korte, H.-J., Krebs, B., van Kralingen, C. G., Marcelis, A. T. M. & Reedijk, J. (1981). Inorg. Chim. Acta, 52, 61–67. CSD CrossRef CAS Web of Science Google Scholar
Krämer, R. & Fritsky, I. O. (2000). Eur. J. Org. Chem. pp. 3505–3510. Google Scholar
Kritchenkov, A. S., Bokach, N. A., Haukka, M. & Kukushkin, V. Yu. (2011). Dalton Trans. 40, 4175–4182. Web of Science CSD CrossRef CAS PubMed Google Scholar
Kuduk-Jaworska, J., Kubiak, M. & Głowiak, T. (1988). Acta Cryst. C44, 437–439. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
Luzyanin, K. V., Tshovrebov, A. G., Guedes da Silva, M. F. C., Haukka, M., Pombeiro, A. J. L. & Kukushkin, V. Yu. (2009). Chem. Eur. J. 15, 5969–5978. Web of Science CSD CrossRef PubMed CAS Google Scholar
Nonius (2000). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Orpen, A. G., Brammer, L., Allen, F. H., Kennard, O., Watson, D. G. & Taylor, R. (1989). J. Chem. Soc. Dalton Trans. pp. S1–83. CrossRef Web of Science Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter & R. M. Sweet, pp. 307–326. New York: Academic Press. Google Scholar
Ravera, M., Gabano, E., Sardi, M., Ermondi, G., Caron, G., McGlinchey, M. J., Müller-Bunz, H., Monti, E., Gariboldi, M. B. & Osella, D. (2011). J. Inorg. Biochem. 105, 400–409. Web of Science CSD CrossRef CAS PubMed Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tskhovrebov, A. G., Bokach, N. A., Haukka, M. & Kukushkin, V. Yu. (2009). Inorg. Chem. 48, 8678–8688. Web of Science CSD CrossRef PubMed CAS Google Scholar
Wheate, N. J., Taleb, R. I., Krause-Heuer, A. M., Cook, R. L., Wang, S., Higgins, V. J. & Aldrich-Wright, J. R. (2007). Dalton Trans. pp. 5055–5064. Web of Science CrossRef Google Scholar
Yip, H.-K., Che, Ch.-M. & Peng, Sh.-M. (1993). J. Chem. Soc. Dalton Trans. pp. 179–187. CSD CrossRef CAS Web of Science Google Scholar
Zutphen, S. van, Pantoja, E., Soriano, R., Soro, C., Tooke, D. M., Spek, A. L. den Dulk, H., Brouwer, J. & Reedijk, J. (2006). Dalton Trans. pp. 1020–1023. Google Scholar