LOW-TEMPERATURE NEUTRON-DIFFRACTION STUDY OF BIS(TRI-PARA-TOLYLPHOSPHINE)HEPTAHYDRIDORHENIUM(VII), [REH7(P(C6H4CH3-4)3)2] - A POLYHYDRIDE COMPLEX WITH A SHORT H=H CONTACT THAT MODELS AN INTERMEDIATE STAGE IN THE OXIDATIVE ADDITION OF DIHYDROGEN AT TRANSITION-METAL CENTERS

Low-temperature neutron diffraction shows that the title compound has an H ... H separation [1.357(7) angstrom] intermediate in length between the accepted ranges for 'classical' non-bonded dihydrides and more recently reported dihydrogen ligands, thus providing a model for the intermediate stages of oxidative addition of dihydrogen at transition metal centres.