The reaction of platinacyclobutanes with phosphines

The volatile products of the thermal and photochemical reactions of phosphines (Ph2PCH2PPh2, PPh3, PHPh2) with the platinacyclobutane compounds [X2PtCH2CH2CH2 (NN)] (where X  Cl, Br and NN  1,10-phenanthroline, 2,2′-bipyridine, (CH2NMe2)2) in several solvents have been determined. The hydrocarbons formed were ethylene, propene and cyclopropane with small amounts of methane, and also propane with PHPh2. Very high relative yields of C2H4 (over 80%) were obtained under some conditions, notably with CH3CN and (CH3)2SO as solvents. Chloromethane (or bromomethane) was also produced with DMSO as solvent. It is suggested that the formation of ethylene involves dissociation of a halide ion and is accompanied by the production of platinum ylids. Hydrogen transfer from PHPh2 can lead to the formation of C3H8.