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A study was conducted to understand the strong negative thermal expansion (NTE) exhibited by scandium trifluoride at low temperature, which maintains a cubic Re[O.sub.3] type structure down to at least 10K. Sc[F.sub.3] is found to be the first material with structure similar to Re[O.sub.3] which provide a clear experimental explanation for the observed NTE mechanism.

The theoretical exploration of the high pressure phases of the ionic salt BaRe[H.sub.9] was carried out motivated by the potential high-temperature superconductivity of 'chemically precompressed' hydrogen-rich compounds. The results provide insight into the structural changes in BaRe[H.sub.9] associated with remarkable lowering of metallization pressure the and the expected metallic turn in BaRe[H.sub.9] at the onset of the [H.sub.2]-containing phase.

A new mechanism is described for the conversion of Re azide complexes to the corresponding Re imido complexes by [N.sub.2] loss. The results have shown that the oxo rhenium complex has reacted with Ph[N.sub.3] through rhenium azide intermediates to produce the cis [beta] oxo-imido complex, where cis [beta]-I is both kinetically and thermodynamically favored over cis [beta]-II.

A new and potentially useful method of chirality transfer from a coordinated ligand to a metal, consisting of a kinetically controlled diastereoselective proton transfer is presented. The diastereomeric methyl rhenium complex is synthesized and treated at 178 degree Celsius with half an equivalent of methanesulfonic acid in order to test this new method.

The derivatives of aromatic heterocycles represented in the deprotonated forms of rhenium carbene complexes are examined and their intrinsic rate constants are studied. It is found that an increase in aromaticity leads to an increase in the intrinsic rate constant.