Rhenium complexes with polyhydrides

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... 

With rhenium there are several possible or probable H2 complexes as well as some cases that are very equivocal. It is believed that the [Re(PR3)2H8]+ ion, obtained by protonation of ReH7(PR3)2 must contain at least one H2 ligand, since a classical structure containing eight H ligands exceeds the possible valence of rhenium. Other protonated species, e.g., [Re(PR3)3H<]+, may well be classical polyhydrides. It is to be noted that protonation occurs only at low temperature otherwise there is a reaction such as the following in which H2 is evolved ... 

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