Dinuclear polyhydrides of rhenium: isolation and characterization of diamagnetic and paramagnetic complexes containing the octahydrodirhenium(n+) ([Re2H8]n+), heptahydrodirhenium((n + 1)+) ([Re2H7](n+1)+), and pentahydrodirhenium((n + 1)+) ([Re2H5](n+1)+) cores (n = 0 or 1) stabilized by phosphine, nitrile, and isocyanide ligands