Synthesis and characterization of Ir (η 4-C 4H 6)[N(SiMe 2CH 2PPh 2) 2]. A non-fluxional five-coordinate iridium(I) complex containing an η 4-butadiene ligand

Abstract

The reaction of the square-planar iridium(I) η 2-cyclooctene complex, Ir(η 2-C 8H 14)[N(SiMe 2CH 2PPh 2) 2], with excess 1,3-butadiene generates excellent yields of the five-coordinate iridium(I) 1,3-butadiene complex, Ir(C 4H 6)[N(SiMe 2CH 2PPh 2) 2]. Both the NMR spectral data and the single crystal X-ray structure reveal that the tridentate amido-diphosphine ligand is coordinated in a quasi facial manner and the 1,3-butadiene unit is bound in a s- cis-η 4-π mode with some σ 2-π component to the bonding. In solution, the butadiene complex shows no fluxional behaviour even at temperatures as high as 85δC.