Polymeric Alkylidene-Bridged Platinum Complex [{Pt2(μ-Cl)2{μ-C(OBu)Me}2}n]: Synthesis, Reactivity, and Quantum Chemical Calculations

H2[PtCl6]·6H2O in dried n-BuOH was found to react with an excess of bis(trimethylsilyl)acetylene (BTMSA), yielding the polymeric alkylidene-bridged platinum complex [{Pt2(μ-Cl)2{μ-C(OBu)Me}2}n] (3). Reactions of complex 3 with monodentate N, P, and S donors afforded dinuclear alkylidene-bridged complexes trans-[{PtCl(L)}2{μ-C(OBu)Me}2] (2-Mepy, 5a; 4-Mepy, 5b; 2-Brpy, 5c; PPh3, 6a; PPh2(4-py), 6b; tht, 7) (tht = tetrahydrothiophene) in yields between 51 and 92%. Owing to a syn and anti arrangement of the butoxy substituents, complexes 5−7 were obtained as diastereomeric mixtures. All comlexes were characterized by means of microanalysis and IR and NMR spectroscopy. Furthermore, X-ray diffraction analyses were performed for the complexes 5a−c and 6a,b, exhibiting central Pt2C2 rings with Pt−Pt distances between 2.573(1) and 2.681(1) Å. Quantum chemical studies of 6a using the AIM theory gave evidence of the bonding in the Pt2C2 moiety in terms of four-centered bonds.