Rhenium polyhydrides

H-D Exchange Reaction of Borane-Lewis Base Adducts by Rhenium Polyhydride Complexes... 

Thus we examined the reactions of borane-Lcwis base adducts with rhenium polyhydride complexes to synthesize highly fluxional polyhydride(borane) complexes. However, treatment of several boranes with the rhenium complexes in deuterated solvents resulted in an unexpected reaction H-D exchange between the boranes and solvents. This is the first example of H-D exchange between sp2 carbon and sp3 boron, and closely associated with metal-catalyzed deuteration of alkanes.4... 

Sutherland B.R., Foiling K., Streib W.E., Ho D.M., Huffman J.C., Caulton K.G. Synthetic and mechanistic features of alcohol elimination between gold aUcoxides and rhenium polyhydrides. Metal polyhedron reconstruction upon protonation. J. Am. Chem. Soc. 1987 109 3489... 

The isotopic perturbation of resonance (IPR) method for ti -H2 characterization depends on the observation of differing chemical shifts and temperature-dependent isotope fractionation in partially deuterated polyhydrides. IPR has been shown to correctly indicate classical configurations, despite low Ti values, for many rhenium polyhydrides.However, IPR sometimes proves useless due to insignificantly small chemical shifts and broad signals. Alternatively, deuteration may exert an influence on equilibria, such as that shown in Eq. (1). Deuteration increases the abundance of (2). However, this effect is offset by greater intramolecular fractionation of deuterium into the ri site of (2) resulting in little IPR shift. 

For additional references on the characterization of rhenium polyhydrides, see Chapter 11 in Vol. 7 of this series. 

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