Rhenium(VII) Oxo−Alkyl Complexes: Reductive and α-Elimination Reactions
journal contributionposted on 06.02.1996, 00:00 by Shiang Cai, David M. Hoffman, Derk A. Wierda
Alkylation of ReO2(CH2CMe3)2X(py) (X = Cl, Br) with ZnR2 at low temperature gives ReO2(CH2CMe3)2R (R = Me, CH2CMe3, CH2SiMe3, Ph) in high yield. The crystal structure of ReO2(CH2CMe3)2Ph shows that it has a distorted trigonal bipyramidal structure with the oxo and Ph ligands in the equatorial plane. Photolysis of ReO2(CH2CMe3)3 in pyridine gives neopentane and ReO2(CHCMe3)(CH2CMe3), and ReO2(CHCMe3)(CH2CMe3) reacts with quinuclidine to give ReO2(CHCMe3)(CH2CMe3)(quinuclidine). In the solid state, ReO2(CHCMe3)(CH2CMe3) has a distorted tetrahedral structure, and ReO2(CHCMe3)(CH2CMe3)(quinuclidine) is trigonal bipyramidal with the neopentylidene and oxo ligands defining the equatorial plane. The Re−N bond distance is long, suggesting the rhenium−quinuclidine interaction is weak. Thermolysis of ReO2(CH2CMe3)2Ph in pyridine gives ReO2(CH2CMe3)(py)3 and neopentylbenzene. An X-ray structure of ReO2(CH2CMe3)(py)3 shows that it is octahedral with trans oxo groups. In solution ReO2(CH2CMe3)(py)3 is unstable in the absence of excess pyridine, and in the solid state it readily loses pyridine. ReO2(CH2CMe3)(py)3 reacts with MeC⋮CMe and PhC⋮CH to form ReO2(CH2CMe3)(alkyne) compounds.