Synthesis, Structure, and Characterization of a Bridging Ethylidene (Perfluoroalkyl)phosphine Platinum Complex

Abstract

Thermolysis of (dfepe)Pt(Et)(O2CCF3) (dfepe = (C2F5)2PCH2CH2P(C2F5)2) in benzene at 80 °C results in the formation of (dfepe)Pt(η2-C2H4). However, at 120 °C in CF3CO2H a bridging ethylidene platinum dimer, [(dfepe)2Pt2(μ-CHMe)(μ-H)][O2CCF3], is produced instead. Product isolation by precipitation with diethyl ether afforded the neutral dimer (dfepe)2Pt2(μ-CHMe3). Alternatively, (dfepe)2Pt2(μ-CHMe) may be prepared at 20 °C by treatment of [(dfepe)Pt(μ-H)]2(H)+ with 1 atm of ethylene. Complete characterization of this species was accomplished by 1H, 13C, and 31P NMR spectroscopy, as well as X-ray diffraction. Investigations probing the mechanism of formation for this μ-alkylidene product are presented. The synthesis of the benzyl complex (dfepe)Pt(CH2Ph)(O2CCF3) and its reversible rearrangement to the η3-benzyl complex [(dfepe)Pt(η3-CH2Ph)]+ upon labilization of trifluoroacetate anion is also reported.