The reversible reaction between olefins and platinum hydrides

Mechanism of the thermal decomposition of carbonyl(.eta.5-cyclopentadienyl)triphenylphosphineiron(II) alkyl derivatives into carbonyl(.eta.5-cyclopentadienyl)hydrido(triphenylphosphine)iron(II) and olefin

“…This was straightforwardly explained by a fast, reversible equilibrium similar to that shown in reaction mechanism 1. A scrambling of deuteriums was also observed by Chatt et al in the decomposition of trans-[Pt(CD2CH3)Br(PEt3)2] , 9 The main feature of the mechanism proposed for the di-«-butyl system is the initial dissociation of a phosphine followed by /3-elimination of a -butyl group. The olefin formed upon ßelimination was shown to remain attached to the platinum.…”

Directly Observed β-H Elimination of Unsaturated PCP-Based Rhodium(III)−Alkyl Complexes

“…Importantly, complex 12 is stable under the conditions in which 13 readily undergoes β -H elimination to afford 6 and propylene. It is known that secondary alkyl complexes are often unstable and either do not form ,, or rapidly isomerize to the more stable 1° alkyl complexes. , The olefin π-complex A , presumably formed after the β -H elimination step, bears two large phosphine ligands. Crowding in the coordination sphere of the metal is expected to favor formation of the n Pr derivative 12 , which is not observed by 1 H and 31 P NMR.…”

“…For instance, Yamamoto et al reported the formation of trans -PdR 2 (PMePh 2 ) 2 (R = n Pr, n Bu) but did not obtain the i Pr or i Bu analogues, and Chatt et al reported the formation of Pt(PEt 3 ) 2 n PrCl, while attempts to obtain Pt(PEt 3 ) 2 i PrCl yielded Pt(PEt 3 ) 2 HCl …”

Olefin and acetylene complexes of platinum and palladium

“…deuterium-labeled complexes, it was shown that the hydrogen atoms attached to either of the carbon atoms of the ethyl group can provide the hydrido ligand. 198 No hydrogendeuterium exchange between fully deuterated ethylene and undeuterated Zeise's dimer to give monodeuterioethylene was observed at 100°in dilute hydrochloric acid, although a slow exchange was observed in toluene at the same temperature. 199 When platinum(II) complexes were treated with terminal olefins in a dimethylformamide-formic acid solvent, dimeric complexes such as 9 containing both -bonded alkyl groups and coordinated carbon monoxide, liberated from the formic H,"+1C" which contains one conventional oxygen-bonded acetylacetone ligand and two -carbon-bonded ligands in a square-planar arrangement around the platinum, a complex of the diolefin 14, formed by elimination of water between two acetylacetone ligands, was formed.206 This unexpected product was conacid, were obtained.200•201 Mesityl oxide complexes of platinum(II) and palladium(II) differ markedly in structure.…”