Cleavage of Metal−Carbon Bonds in Hydride-Bridged Platinum and Palladium A-Frame Complexes

• Published in: Organometallics Vol. 15; no. 7; pp. 1760 - 1764
• Main Authors: Xu, Chongfu, Anderson, Gordon K
• Format: Journal Article
• Language: English
• Published: American Chemical Society 02-04-1996
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om950931x

The hydride-bridged A-frame complexes [RPt(μ-H)(μ-dppm)2PtR‘]PF6 and [RPt(μ-H)(μ-dppm)2PdR‘]PF6 react with HCl (generated by reaction of acetyl chloride with water) in acetone-d 6 solution by cleavage of one of the metal−carbon bonds. In the diplatinum systems the relative rates of Pt−C bond cleavage decrease in the order Me > Et > Ph, resulting in a single product in each case. For the heterometallic complexes reaction is faster at palladium, but mixtures of [RPt(μ-H)(μ-dppm)2PdCl]PF6 and [ClPt(μ-H)(μ-dppm)2PdR‘]PF6 result in several instances. Further reaction of these with HCl and/or CCl4 generates the chloride-bridged species [RPt(μ-Cl)(μ-dppm)2PdCl]PF6, formed, in some cases, by migration of the organic group from palladium to platinum. These complexes have been prepared also by reaction of [PtR(dppm-PP)(dppm-P)]PF6 with [PdCl2(cod)]. The [RPt(μ-Cl)(μ-dppm)2PdCl]PF6 complexes are fluxional at 298 K, although the motion may be arrested slightly below ambient temperature. A mechanism involving reversible bridge opening is proposed to account for the fluxional behavior.