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

Abstract

The reaction of [(PPh3)2Pt(η3-CH2CCPh)]X (X = CF3SO3 -, BF4 -, PF6 -) with CNR (R = C(CH3)3, CH2Ph) yields a mixture of the η1-propargyl and -allenyl complexes trans-[(PPh3)2Pt(η1-CH2C⋮CPh)(CNR)]+ and trans-[(PPh3)2Pt(η1-CPhCCH2)(CNR)]+, respectively, in about a 6/1 proportion. Isolation of the pure propargyl complex was possible in several cases (R = C(CH3)3, X = CF3SO3 -; R = CH2Ph, X = BF4 -, PF6 -). In solution the cationic complex trans-[(PPh3)2Pt(η1-CH2C⋮CPh)(CNC(CH3)3)]+ rearranges to an indenyl complex which was isolated as the triflate salt trans-[(PPh3)2Pt(η1-1H-inden-2-yl)(CNC(CH3)3)]CF3SO3 (4). In contrast trans-[(PPh3)2Pt(η1-CH2C⋮CPh)(CNCH2Ph)]+ does not undergo this rearrangement under similar conditions. The structure of 4·2THF has been determined by X-ray diffraction techniques.