ChemInform Abstract: Low-Valent Oxo Compounds. Part. 7. Low-Valent Rhenium-Oxo Alkyl and -Oxo Hydride Complexes. The Stabilizing Influence of the Oxo Ligand.

ChemInform Abstract

The rhenium(III)-oxo alkyl bis(acetylene) complexes (III) are prepared by alkylation of the iodide derivative (I) with the dialkylzinc compounds (II). The analogous oxo hydride compounds (VI) are formed by decarboxylation of the formate complexes (V). These compounds are characterized by IR and ¹H NMR spectra and an X-ray crystal structure determination of (IIIa) (space group P21/m, Z=2). The oxo alkyl compounds are thermally stable and there is no evidence for β-hydrogen elimination from ethyl or isopropyl ligands even on decomposition. Olefin insertion into the Re-H bonds in (VI) is also not observed. Reactions of the compounds with strong acids result in protonation of the oxo ligand without loss of alkane or H2. The importance of the terminal oxo group as a stabilizing ligand for alkyl complexes is discussed in light of these results.