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

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 P2(1)/n with Z = 2, a = 9.271 (2), b = 19.726 (4), c = 9.830 (2) A, beta = 111.83 (3)degrees, V = 1668.8 (6) A3, R = 0.0262, and from dichloromethane with two solvent molecules as trans-[PtC12(AsPh3)2].2CH2C12 in Pbca with Z= 4, a = 20.582 (4), b = 8.146 (2), c = 23.491 (5) A, V = 3938.5 (14) A3 and R = 0.0316. From dichloroethane it crystallizes with one solvent molecule as trans-[PtC12(AsPh3)2].C2H4C12 in P1 with Z = 1, a = 9.390 (2), b= 9.548 (2), c = 11.931 (2) A, alpha = 109.70 (3), beta = 108.26 (3), gamma = 98.77 (3) , V= 915.6 (3) A3, R = 0.0390, and from benzene with half a solvent molecule as trans- [PtC12(AsPh3)2].0.5C6H6 in P2(1)/n with Z = 4, a = 11.778 (2), b = 18.712 (4), c = 16.647 (3) A, beta = 104.78 (3) , V= 3547.3 (12) A3 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) A and the Pt-C distances are in the range 2.309 (2)-2.2839 (9) A. 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 A (95% confidence interval) for Pt-As and Pt-C1, 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 A3 per metal complex.

Geometry variation of complex ions in crystals †

“…The methods used are based on those we and others have used previously. 2,13, 15 The total variance, σ, of a particular geometric parameter in a given ion is composed of two terms as in eqn. (1).…”

“…In related work Englert and colleagues carried out a series of studies on tungsten, indium and cobalt complexes which show considerable variation in structure as a function of solvation and other aspects of the crystal environment. 14 Careful study of several solvates of a platinum() complex 15 and a series of studies using crystallographic and theoretical approaches in tin chemistry 16 have highlighted the effects of crystal packing on molecular geometry in specific systems.…”

Cis/trans isomers of PtX 2 L 2 (X = halogen, L = neutral ligand); the crystal structures of two polymorphs of cis-dichlorobis(dibenzyl sulfido-κS)platinum(II) in the temperature range 100–295 K

“…This can be achieved in a number of ways, i.e. the study of crystal structures with more than one metal complex in the asymmetric unit (Lö vqvist, 1996), charged metal complexes with different counterions (Ericson et al, 1992), different crystalline solvates (Johansson et al, 2000) or different polymorphs (Kapoor et al, 1996). The structure of a toluene solvate of the title compound cis-PtCl 2 (Bz 2 S) 2 , where Bz 2 S is dibenzyl sulfide, is known (Braunmü hl et al, 1998) and here we report the structure of two polymorphs crystallizing in P " 1 1 and C2/c, respectively, with no solvate molecules.…”

trans-Dichloridobis[dicyclohexyl(4-isopropylphenyl)phosphane-κP]platinum(II) acetone monosolvate

“…These complexes form part of a class of symmetrical square-planar complexes that usually crystallize with the metal atom on a crystallographic inversion center, thus imposing a disordered packing arrangement (see Otto, 2001;Otto et al, 2000;Chen et al,1991, Kuwabara & Bau, 1994 for examples on Rh, Ir, Pd and Pt, respectively). Very often the Pt complexes display a trans geometry (Otto & Roodt, 1997;Johansson et al, 2000), but some number with a cis geometry have also been reported (Otto & Muller, 2001; Otto & Johansson, 2001). Pt(II) complexes, along with the Vaska-type complexes, are useful model complexes and provide several probing methods, e.g.…”