Di- and trinuclear phosphido-bridged platinum complexes. Crystal structures of [Pt{CH2=CHC(O)OMe}(PPh3)2], trans-[Pt2(μ-PPh2)2I2(PPh3)2] and cis,cis,cis-[Pt3(μ-I)2(μ-PPh2)2Cl0.5I1.5(PPh3)2]

The readily available Pt(0) methyl acrylate complex [Pt{CH2=CHC(O)OMe}(PPh3)(2)] (2) allows access to the known, mixed-valence trinuclear cluster [Pt-3(mu-PPh2)(3)Ph(PPh3)(2)] (3) in 64% yield. Oxidation of 3 with 2 equivalents of I-2 afforded the new trinuclear complex [Pt-3(mu-I)(2)(mu-PPh2)(2)I-2(PPh3)(2)] (4) whose molecular structure is similar to that of the related compound of empirical formula [Pt-3(mu-I)(2)(mu-PPh2)(2)Cl0.5I1.5(PPh3)(2)] (5) which has been generated by oxidation of 3 with successively 1 equivalent of I-2 and 1 equivalent of C6H5ICl2. In these complexes, the four halogen atoms lie on the same side of the almost aligned platinum atoms and the nearly square-planar coordination planes of the metal atoms adopt a "japanese screen", chair-like conformation. The reaction of the dinuclear, metal-metal bonded Pt(I)-Pt(I) complex [Pt-2(mu-PPh2)(2)(PPh3)(2)] with one equivalent of I-2 afforded the Pt(II) complex [Pt-2(mu-PPh2)(2)I-2(PPh3)(2)] (6). The molecular structures of complexes 2 center dot CH2Cl2, [Pt-3(mu-I)(2)(mu-PPh2)2(I1.3Cl0.7)(PPh3)(2)][Pt-3(mu-I)(2)(mu-PPh2)(2)(I1.7Cl0.3)(PPh3)(2)]center dot C6H5Cl center dot 3CH(2)Cl(2) (5A center dot 5B center dot C6H5Cl center dot 3CH(2)Cl(2)) and 6 have been established by single crystal X-ray diffraction studies.