cis-Dichloridobis{[4-(dimethylamino)phenyl]diphenylphosphane-κP}platinum(II) ethyl acetate monosolvate

The title compound, [PtCl2(C20H20P)2]·C4H8O2, crystallizes with the Pt atom in a distorted cis-square-planar geometry. The Pt—P bond lengths are 2.2490 (19) and 2.253 (2) Å, and the Pt—Cl bond lengths are 2.344 (2) and 2.3475 (18) Å. Some weak C—H⋯Cl and C—H⋯O interactions involving the solvate molecule were observed.


Related literature
For a review on related compounds, see: Spessard & Miessler (1996). For the synthesis of the starting materials, see: Drew & Doyle (1990).
Financial assistance from the South African National Research Foundation (SA NRF), the Research Fund of the University of Johannesburg and SASOL is gratefully acknowledged. The University of the Free State (Professor A. Roodt) is thanked for the use of its diffractometer.
The Cl1-Pt-P angles are 175.95 (7)° and 84.93 (7)° respectively for P1 and P2. Some weak intermolecular interactions were observed and are reported in Table 1.
The title compound compares well with other closely related Pt(II) complexes from the literature containing two chloro and two tertiary phosphine ligands in a cis-geometry. The title compound, having Pt-Cl bond lengths of 2.344 (2)Å and 2.3475 (18)Å and Pd-P bond lengths of 2.2490 (19)Å and 2.253 (2)Å, fits well into the typical range for complexes of this kind. It is notable that the title compound crystallized as a solvated complex, as these type of Pt(II) complexes tend to crystallize as solvates.

Refinement
The aromatic, methylene, and methyl H atoms were placed in geometrically idealized positions (C-H = 0.95Å-0.98Å) and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C) for aromatic and methylene H atoms, and U iso (H) = 1.5U eq (C) for methyl H atoms respectively. Methyl torsion angles were refined from electron density.
The highest residual electron density peak of 1.53 e×Å 3 is 1.14Å from Pt and the deepest hole of -1.87 e×Å 3 is 0.87Å from Pt representing no physical meaning.  Fig. 1. The structure of title compound with the atom numbering scheme. Displacement ellipsoids are drawn at 50% probability level. H atoms are presented as a small spheres of arbitrary radius. For the C atoms, the first digit indicates ring number and the second digit indicates the position of the atom in the ring. Some lables have been omitted for clarity, all rings have been numbered in the same, systematic manner.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.