Rhenium(VII) Oxo−Alkyl Complexes: Reductive and α-Elimination Reactions

Alkylation of ReO 2 (CH 2 CMe 3 ) 2 X(py) (X = Cl, Br) with ZnR 2 at low temperature gives ReO 2 (CH 2 CMe 3 ) 2 R (R = Me, CH 2 CMe 3, CH 2 SiMe 3, Ph) in high yield. The crystal structure of ReO 2 (CH 2 CMe 3 ) 2 Ph shows that it has a distorted trigonal bipyramidal structure with the oxo and Ph ligands in the equatorial plane. Photolysis of ReO 2 (CH 2 CMe 3 ) 3 in pyridine gives neopentane and ReO 2 (CHCMe 3 )(CH 2 CMe 3 ), and ReO 2 (CHCMe 3 )(CH 2 CMe 3 ) reacts with quinuclidine to give ReO 2 (CHCMe 3 )(CH 2 CMe 3 )(quinuclidine). In the solid state, ReO 2 (CHCMe 3 )(CH 2 CMe 3 ) has a distorted tetrahedral structure, and ReO 2 (CHCMe 3 )(CH 2 CMe 3 )(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 ReO 2 (CH 2 CMe 3 ) 2 Ph in pyridine gives ReO 2 (CH 2 CMe 3 )(py) 3 and neopentylbenzene. An X-ray structure of ReO 2 (CH 2 CMe 3 )(py) 3 shows that it is octahedral with trans oxo groups. In solution ReO 2 (CH 2 CMe 3 )(py) 3 is unstable in the absence of excess pyridine, and in the solid state it readily loses pyridine. ReO 2 (CH 2 CMe 3 )(py) 3 reacts with MeC⋮CMe and PhC⋮CH to form ReO 2 (CH 2 CMe 3 )(alkyne) compounds.