The nature and degree of the cooperativity of (η-CH)-metal and metal-CO bonds in half-sandwich complexes of groups 5, 7, 9, and 11 transition metals

In this computational study the nature of metal-ligand bonds and their cooperativity in organotransition metal complexes of the type [(η 5 -C 5 H 5 )M(CO) n ], where n = 1, M = Cu( i ), Ag( i ), Au( i ); n = 2, M = Co( i ), Rh( i ), Ir( i ); n = 3, M = Mn( i ), Tc( i ), Re( i ); n = 4; M = V( i ), Nb( i ), Ta( i ), are investigated. The presence and extent of bond cooperativity were determined by calculating the bond dissociation energies (BDEs) and interaction energies (IEs). The energy decomposition analysis-natural orbitals for chemical valence (EDA-NOCV) method was applied to study the nature of metal-ligand bonds and provide insights into the origin of observed cooperativities or anticooperativities. The results indicated that the cooperativities vary by changing the metal centers and coordination environments. Positive cooperativity was observed in Cu( i ), Ag( i ), Au( i ), Co( i ), Mn( i ), V( i ), Nb( i ), and Ta( i ) complexes, whereas Rh( i ), Ir( i ), Tc( i ), and Re( i ) complexes exhibited negative cooperativity (anticooperativity). It is shown that, the cooperativity always has the same quantitative effect on the interaction energies of two cooperated chemical bonds but may have different effects on their nature.