LAUSR

Abstract Towards a better understanding of the dynamic processes within eight-coordinate rhenium pentahydride complexes, a set of eight-coordinate rhenium(V) pentahydride complexes supported by two triphenylphosphine ligands and either a bidentate amine with a pendant functional group (1,2-diaminoethane, 1,3-diaminopropane, 2-aminoethanol) or by an unsymmetrically-substituted aromatic amine ligand (3-aminopyridine or 3-picoline) was prepared from thermolysis reactions of ReH7(PPh3)2. Variable temperature 1H NMR spectroscopy and simulation of those results indicate a previously uncharacterized exchange of hydrogen between the unique hydride ligand residing in a dodecahedral B site and hydrogen atoms from adventitious water. The same data also indicate two processes for hydride ligand fluxionality and a process for isomer interconversions of the complexes supported by an unsymmetrically substituted aromatic amine ligand. The hydride exchange process that exchanges A site hydride ligands also exchanges B site ligands. The likely mechanism for the A and B site atom exchanges involves concerted, successive, inversions of the A site ligands into B sites and concomitant inversions of B site ligands into A sites of the D2d dodecahedron. Values of ΔG‡, ΔH‡, and ΔS‡ for all of the dynamic processes were determined.