Synthesis and redox properties of cis-[ReCl(NCR)(Ph2PCH2CH2PPh2)2](R = alkyl or aryl) complexes with a cis-phosphine rhenium(I) centre
Abstract
Treatment of a solution of trans-[ReCl(N2)(dppe)2](dppe = Ph2PCH2CH2PPh2) in toluene with the appropriate organonitrile in sunlight afforded cis-[ReCl(NCR)(dppe)2]1(R = C6H4NEt2-4, C6H4OMe-4, C6H4Me-4, Ph, C6H4F-4, C6H4Cl-4, C6H4NO2-4, CH2C6H4Cl-4, Et, Pri or But) the 31P-{1H} NMR spectra of which have been analysed as ABCD spin systems. Cyclic voltammograms of the complexes, in aprotic medium at a Pt electrode, show a single-electron reversible oxidation at half-wave anodic potentials (1E½ox) in the range –0.20 to –0.02 V vs. saturated calomel electrode (at –20 °C) which is followed by a second anodic process at a higher potential. For the aromatic nitriles, direct or inverse linear correlations are observed between 1E½ox and the Hammett constant, σp′, of the phenyl substituent or the ν(NC) frequency, respectively.