Structure and Bonding of Transition Metal Dihydrogen Complexes [M(CO)5(H2)] (M = Cr, Mo, W)

Important intermediates in catalytic hydrogenation, η2‐dihydrogen complexes are also appealing subjects for theoretical studies. The MH2 binding enthalpies for the complexes [M(CO)5(H2)] (M = Cr, Mo, W) were calculated at the CCSD(T)/MP2 level as 15.9 (M = Cr), 12.8 (M = Mo), and 16.3 kcal mol−1 (M = W). Charge decomposition analysis suggests that H2 is a significant σ donor and a moderate π acceptor. The topological analysis of the electron density distribution indicates a cyclic structure for the MH2 moiety.