Metal complexes of unsaturated tertiary phosphines and arsines. Part IV. Bromination of chelate complexes of platinum(II) formed by olefinic tertiary arsines
- 1 January 1967
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc. A
- p. 1260-1263
- https://doi.org/10.1039/j19670001260
Abstract
The reactions with bromine of platinum(II) complexes containing a co-ordinated double bond have been studied. The chelate complex PtBr2,o-arsine formed by o-styryldimethylarsine, o-CH2:CH·C6H4·AsMe2, reacts with one equivalent of bromine to give an orange, insoluble compound PtBr4,o-arsine which contains neither free nor co-ordinated double bonds. On heating this compound in methanol, hydrogen bromide is eliminated and a methoxy-derivative of the initial chelate complex, of formula PtBr2,o-MeOCH:CH·C6H4·AsMe2, is formed. The chelate complex PtBr2,o-arsine formed by o-allylphenyldimethylarsine, o-CH2:CH·CH2·C6H4·AsMe2, also reacts with bromine to form an orange compound PtBr4,o-arsine. This readily loses bromine in organic solvents, re-forming the initial chelate complex, but on heating in a number of alcohols, hydrogen bromide is eliminated. The alkoxy-substituted chelate complexes so formed are assigned the structure PtBr2,o-RO·CH2·CH:CH·C6H4·AsMe2(R = Me, Et, Prn, or Pri) on the basis of the n.m.r. spectrum of the methoxy-derivative, showing that the double bond has shifted from its position in the initial chelate complex. A dimeric, halogen-bridged structure with metal–carbon σ-bonds is suggested for the complexes of formula PtBr4,o-arsine, and possible mechanisms for the reactions are discussed.Keywords
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