Dihydrogen Activation by Cobaloximes with Various Axial Ligands

We
have investigated the effect of axial ligands on the ability
of cobaloximes to catalyze the generation of transferable hydrogen
atoms from hydrogen gas and have learned that the active catalyst
contains one and only one axial ligand. We have, for example, shown
that Co­(dmgBF2)2 coordinates only one Ph3P and that the addition of additional Ph3P (beyond
1 equiv) to solvated Co­(dmgBF2)2 does not affect
its catalytic turnover for H• transfer from H2.