Reaction of Isocyanides with [(PPh₃)₂Pt(η³-CH₂CCPh)]⁺ and the Formation of the Indenyl Complex <i>trans</i>-[(PPh₃)₂Pt(η¹-1<i>H</i>-inden-2-yl)(CNC(CH₃)₃)]⁺

Abstract

The reaction of [(PPh 3 ) 2 Pt(η 3 -CH 2 CCPh)]X (X = CF 3 SO 3 -, BF 4 -, PF 6 - ) with CNR (R = C(CH 3 ) 3, CH 2 Ph) yields a mixture of the η 1 -propargyl and -allenyl complexes trans -[(PPh 3 ) 2 Pt(η 1 -CH 2 C⋮CPh)(CNR)] + and trans -[(PPh 3 ) 2 Pt(η 1 -CPh C CH 2 )(CNR)] +, respectively, in about a 6/1 proportion. Isolation of the pure propargyl complex was possible in several cases (R = C(CH 3 ) 3, X = CF 3 SO 3 -; R = CH 2 Ph, X = BF 4 -, PF 6 - ). In solution the cationic complex trans -[(PPh 3 ) 2 Pt(η 1 -CH 2 C⋮CPh)(CNC(CH 3 ) 3 )] + rearranges to an indenyl complex which was isolated as the triflate salt trans -[(PPh 3 ) 2 Pt(η 1 -1 H -inden-2-yl)(CNC(CH 3 ) 3 )]CF 3 SO 3 ( 4 ). In contrast trans -[(PPh 3 ) 2 Pt(η 1 -CH 2 C⋮CPh)(CNCH 2 Ph)] + does not undergo this rearrangement under similar conditions. The structure of 4 ·2THF has been determined by X-ray diffraction techniques.