Pyridine(diimine) Chelate Hydrogenation in a Molybdenum Nitrido Ethylene Complex

Addition of H-2 gas to the aryl-substituted pyridine(diimine) molybdenum nitride ((PDI)-P-iPr)Mo(N)-(C2H4) ([1-(N)(eta(2)-C2H4)]; (PDI)-P-iPr = 2,6-(2,6-iPr(2)-C6H3N=CMe)(2)C5H3N) in the presence of the rhodium hydride precatalyst (eta(5)-C5Me5)(py-Ph)Rh(H) ([Rh H]; py-Ph = 2-phenylpyridine) resulted in partial hydrogenation of the central pyridine of the (PDI)-P-iPr chelate to yield ((THPDI)-T-iPr)-Mo(N)(C2H4) ([2-(N)(eta(2)-C2H4)]; (THPDI)-T-iPr = 2,6-(2,6-iPr(2)-C6H3N=CMe)(2)C5H6N). The product, [2-(N)(eta(7)-C2H4)], was structurally and spectroscopically characterized, and its electronic structure was examined by density functional theory (DFT). The stepwise addition of H atoms from [Rh-H] to [1-(N)(eta(2)-C2H4)] was computed to be thermodynamically viable by DFT.