141091-20-5Relevant articles and documents
Carbonylation of organoplatinum dimers bridged by (diphenylphosphino)cyclopentadienyl ligands. Structural characterization of complexes containing 1,1- or 1,2-substituted η1-cyclopentadienyl groups and reductive elimination of ketones
Fallis, Kathleen A.,Anderson, Gordon K.,Lin, Minren,Rath, Nigam P.
, p. 478 - 488 (2008/10/08)
The complexes [Pt2R2(μ-C5H4PPh 2)2] (1a-e: R = Me, Et, neo-Pe (CH2CMe3), Ph, Bz (CH2-Ph)) react with carbon monoxide to produce [Pt2R2(CO)2(μ-η1-C 5H4PPh2)2] (2a-e), in which the cyclopentadienyl groups are 1,2-substituted by Pt and P. The R and CO ligands occupy mutually trans positions, and the complexes exist in solution as both syn and anti forms. The molecular structures of the methyl and neopentyl derivatives have been determined by X-ray diffraction, and they adopt anti and syn conformations, respectively. Thermolyses of these complexes in the presence of CO leads to the platinum(I) dimer [Pt2(CO)2(μ-η1-C5H 4PPh2)2] (5), in which both cyclopentadienyl rings are 1,1-substituted, and the appropriate ketone. The molecular structure of 5 reveals a Pt-Pt distance of 2.583(1) A?. Careful monitoring by NMR spectroscopy of the carbonylation/reductive-elimination sequence allows the identification of the intermediates [Pt2R(COR)(μ-η1-C5H4PPh 2)2] (3b,c) and [Pt2R(CO)(COR)(μ-η1-C5H 4PPh2)2] (4b,c). The molecular structure of 4c indicates that the complex contains one 1,1- and one 1,2-substituted cyclopentadienyl moiety and a Pt→Pt dative bond. A mechanism for the carbonylation/reductive-elimination sequence is proposed.
