The stereochemistry of β -diketo complexes with trimethylplatinum IV. I. The crystal structure of trimethyl 4:6 dioxononyl platinum

An X-ray analysis has been made of the crystalline complex between trimethylplatinum and 4:6-dioxononane, empirical formula (CH3)3Pt(C3H7CO. CH CO C3H7). There are two centrosymmetrical dimeric molecules in a monoclinic unit cell having a = 14.71, b = 10.55, c = 9.15 Å, β = 102.8°, space group P21/a. The atomic positions have been determined by three-dimensional analysis and refined by the method of least squares. The final value of the residual R was 0.076. Each platinum in the binuclear complex is octahedrally co-ordinated to three methyl groups in cis configuration (Pt—C = 2.02 + 0.02 Å), to two oxygens of one β-diketone (Pt—O = 2.15 + 0.01 Å) and to the central carbon atom (the ‘active methylene’) of the other diketone (Pt—C = 2.39 + 0.03 Å). This and the similar compound reported in part II, provide the first examples of β-diketones acting as bridges in polynuclear complexes and of β-diketones acting as tridentate groups. Preliminary crystallographic data for trimethylplatinic acetylacetonate have also been obtained.