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

A series of structures of trans-dichlorobis(tripbenylarsine)platinum(II), r ecrystallized from four different solvents, have been characterized by X-ra y crystallography and were shown to crystallize as different solvates (same metal complex, different crystallization solvents). Their geometric differ ences induced by packing and solvent molecules were analysed with half-norm al probability plots and root-mean-square deviations. The recrystallization solvents used in the investigation were 1,1,1-trichloroethane, dichloromet hane, 1,2-dichloroethane and benzene, and the following crystallization mod es were obtained. From 1,1,1-trichloroethane the metal complex crystallizes without solvent as trans-[PtCl2(AsPh3)(2)] in P2(1)/n with Z = 2, a = 9.27 1(2), b = 19.726 (4). c = 9.530 (2) Angstrom, beta = 111.83 (3)degrees, V = 1668.8 (6) Angstrom(3), R = 0.0262, and from dichloromethane with two solv ent molecules as trans-[PtCl2(AsPh3)(2)]. 2CH(2)Cl(2) in Pbca with Z=4, a = 20.582(4), b = 8.146(2), c = 23.491(5) Angstrom, V = 3938.5 (14) Angstrom( 3) and R = 0.0316. From dichloroethane it crystallizes with one solvent mol ecule as trans-[PtCl2-(AsPh3)(2)]. C2H4Cl2 in P (1) over bar with Z = 1, a = 9.390(2), b = 9.548 (2), c = 11.931 (2) Angstrom, alpha = 109.70 (3), bet a = 108.26 (3), gamma = 98.77 (3)degrees, V = 915.6 (3) Angstrom(3), R = 0. 0390, and from benzene with half a solvent molecule as trans-[PtCl2 (AsPh3) (2)].- 0.5C(6)H(6) in P2(1)/n with Z = 4, a = 11.778 (2), b = 18.712 (4), 1 6.647 (3) Angstrom, beta = 104.78 (3)degrees, V = 3547.3 (12) Angstrom(3) a nd R = 0.0303. In all four compounds platinum(II) coordinates to triphenyla rsine and chloride in a pseudo-square-planar trails configuration. The Pt-A s distances are in the range 2.4104 (4)-2.3923 (4) A and the Pt-Cl distance s are in the range 2.309 (2)-2.2839(9) Angstrom. 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 tha t the largest geometric differences. within the metal complex, are in the b ond and torsion angles around the As-C bonds. Very similar torsion angles w ere observed around the Pt-As bond for all the structures, except for one A sPh3 ligand in the benzene solvate, which differs by about 10 degrees from the others. The metal-donor bond distance varies by as much as 0.019 and 0. 025 Angstrom (95% confidence interval) for Pt-As and Pt-Cl, respectively. T he variations are essentially caused by intermolecular interactions. Packin g 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 no n-solvated compound, with a difference of approximately 22 Angstrom(3) per metal complex.