The photodecomposition of platinacycloalkanes in solution: II. 1,4-butanediylplatinum(II) and (IV) compounds

Abstract

The products of the photolysis of a number of platinacyclopentanes in solution at 25°C under a variety of conditions have been determined. With [I 2P tCH 2CH 2CH 2C H 2(L 2)] (L = PMe 2Ph, PPh 3) in CH 2Cl 2, CH 2Br 2 and (CH 3) 2SO the hydrocarbon products are exclusively ethylene and but-1-ene. Formation of the latter through a 1,3-hydrogen shift is preceded by phosphine ligand dissociation. The photolysis of [ICH 3P tCH 2CH 2C H 2(L 2)] gave methane, ethylene, but-1-ene and n-pentane together with a little n-butane, the methane being formed from internal hydrogen abstraction by the CH 3 group in the excited reactant molecule. Photodecomposition of the platinum(II) compounds [P tCH 2CH 2CH 2C H 2(L 2)] (L = (PMe 2Ph) 2, (PPh 3) 2, Ph 2PCH 2CH 2PPh 2) gave ethylene, but-1-ene, pent-1-ene (with the halogenated solvents) and with some systems appreciable yields of n-butane, the latter being the results of internal abstraction of two hydrogen atoms by the C 4H 8 moiety. The formation of pentene is probably preceeded by the addition of CH 2Cl 2 or CH 2Br 2 to the excited reactant molecule. Addition of diphenylphosphine promotes the production of n-butane.