Preparation and Spectroscopic Properties of Cyclohexyneplatinum(0) Complexes Containing Ditertiary Arylphosphines and of Their Protonation Products

Abstract

Cyclohexyneplatinum (0) complexes Pt(C₆H₈)(P~P) [P~P = (Z)-Ph₂PCH=CHPPh₂, Ph₂P(CH₂)_3- PPh₂ or Ph₂P(CH₂)₄PPh₂] and Pt(C₆H₈)(PMePh₂)₂ have been prepared by displacement of tri- phenylphosphine from Pt(C₆H₈)(PPh₃)₂. Like the known compound containing Ph₂PCH₂CH₂PPh₂, these complexes are readily protonated by both strong and weak acids (HY) to give η¹-cyclohexen-1- yl -platinum(II) complexes PtY (C₆H₉)(P~P) (Y = Cl , SPh , O₂CMe, CH₂CN, OMe , OH). An excess of HCl rapidly cleaves the Pt-C₆H₉ bond giving PtCl₂(P~P) complexes identical with those made from PtCl₂(cycloocta-1,5-diene) and P~P. The methoxo complexes react rapidly with water to give the hydroxo complexes and with CO to give methoxycarbonyl complexes Pt(CO₂Me)(C₆H₉)- (P~P). The i.r ., ¹H and ³¹P{1H} n.m.r . spectra of the new complexes are reported and trends in the ³¹P chemical shifts ( δ_P ) and in the ¹⁹⁵Pt-³¹P coupling constants (¹J_Pt,P) are compared with those reported in the literature for related systems.