Acta Crystallographica Section B

Structural Science

Volume 56, Part 2 (April 2000)

research papers

Acta Cryst. (2000). B56, 226-233 [ doi:10.1107/S0108768199014500 ]

Packing effects on the geometry of neutral platinum(II) complexes due to solvate molecules: the structure of trans-dichlorobis(triphenylarsine)platinum(II)

M. H. Johansson, S. Otto, A. Roodt and Å. Oskarsson

Abstract: A series of structures of trans-dichlorobis(triphenylarsine)platinum(II), recrystallized from four different solvents, have been characterized by X-ray crystallography and were shown to crystallize as different solvates (same metal complex, different crystallization solvents). Their geometric differences induced by packing and solvent molecules were analysed with half-normal probability plots and root-mean-square deviations. The recrystallization solvents used in the investigation were 1,1,1-trichloroethane, dichloromethane, 1,2-dichloroethane and benzene, and the following crystallization modes were obtained. From 1,1,1-trichloroethane the metal complex crystallizes without solvent as trans-[PtCl₂(AsPh₃)₂] in P2₁/n with Z = 2, a = 9.271 (2), b = 19.726 (4), c = 9.830 (2) Å, [beta] = 111.83 (3)°, V = 1668.8 (6) Å³, R = 0.0262, and from dichloromethane with two solvent molecules as trans-[PtCl₂(AsPh₃)₂]·2CH₂Cl₂ in Pbca with Z = 4, a = 20.582 (4), b = 8.146 (2), c = 23.491 (5) Å, V = 3938.5 (14) Å³ and R = 0.0316. From dichloroethane it crystallizes with one solvent molecule as trans-[PtCl₂(AsPh₃)₂]·C₂H₄Cl₂ in P $\overline 1$ with Z = 1, a = 9.390 (2), b = 9.548 (2), c = 11.931 (2) Å, [alpha] = 109.70 (3), [beta] = 108.26 (3), [gamma] = 98.77 (3)°, V = 915.6 (3) Å³, R = 0.0390, and from benzene with half a solvent molecule as trans-[PtCl₂(AsPh₃)₂]·0.5C₆H₆ in P2₁/n with Z = 4, a = 11.778 (2), b = 18.712 (4), c = 16.647 (3) Å, [beta] = 104.78 (3)°, V = 3547.3 (12) Å³ and R = 0.0303. In all four compounds platinum(II) coordinates to triphenylarsine and chloride in a pseudo-square-planar trans configuration. The Pt-As distances are in the range 2.4104 (4)-2.3923 (4) Å and the Pt-Cl distances are in the range 2.309 (2)-2.2839 (9) Å. The solvents have a large influence on the packing, resulting in different space groups or different occupancies in the same space group. Half-normal probability plots show that the largest geometric differences, within the metal complex, are in the bond and torsion angles around the As-C bonds. Very similar torsion angles were observed around the Pt-As bond for all the structures, except for one AsPh₃ ligand in the benzene solvate, which differs by about 10° from the others. The metal-donor bond distance varies by as much as 0.019 and 0.025 Å (95% confidence interval) for Pt-As and Pt-Cl, respectively. The variations are essentially caused by intermolecular interactions. Packing efficiency is expressed as the volume filled by each metal complex in the unit cell and is calculated by subtracting the sum of the solvent molecule volumes from the total volume of the unit cell and then dividing by Z. The efficiency is largest in the dichloroethane solvate and smallest in the non-solvated compound, with a difference of approximately 22 Å³ per metal complex.

Keywords: Packing effects; Platinum(II) complexes; Solvents.


	Structure factor file (CIF format) (249.7 kbytes) Contains datablock 1

	Structure factor file (CIF format) (386.8 kbytes) Contains datablock 2

	Structure factor file (CIF format) (263.6 kbytes) Contains datablock 3

	Structure factor file (CIF format) (532.7 kbytes) Contains datablock 4

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