Bonding in Binuclear Carbonyl Complexes M₂(CO)₉(M = Fe, Ru, Os)

Abstract

Quantum-chemical density functional theory calculations using the BP86 functional in conjunction with a triple-ζ basis set and dispersion correction by Grimme with Becke-Johnson damping D3(BJ) were performed for the title molecules. The nature of the bonding was examined with the quantum theory of atoms in molecules (QTAIM) and natural bond order (NBO) methods and with the energy decomposition analysis in conjunction with the natural orbital for chemical valence (EDA-NOCV) analysis. The energetically lowest-lying form of Fe(CO) is the triply bridged D structure, whereas the most stable structures of Ru(CO) and Os(CO) are singly bridged C species. The calculated reaction energies for the formation of the cyclic trinuclear carbonyls M(CO) from the dinuclear carbonyls M(CO) are in agreement with experiment, as the iron complex Fe(CO) is thermodynamically stable in these reactions, but the heavier homologues Ru(CO) and Os(CO) are not. The metal-CO bond to the bridging CO ligands is stronger than the bonds to the terminal CO ligands. This holds for the triply bridged D structures as well as for the singly bridged C or C species. The analysis of the orbital interactions with the help of the EDA-NOCV method suggests that the overall M→CO π backdonation is always stronger than the M←CO σ donation. The bridging carbonyls are more strongly bonded than the terminal CO ligands, and they are engaged in stronger σ donation and π backdonation, but the formation of bridging carbonyls requires reorganization energy, which may or may not be compensated by the stronger metal-ligand interactions. The lower-lying D form of Fe(CO) and C structures of Ru(CO) and Os(CO) are due to a delicate balance of several forces.

A computational study on the nature, strength and cooperativity of bonds in [M(η5–C60Me5)(CO)n] and [M(η5–Cp)(CO)n] (n = 3, M = Mn(i), Tc(i), Re(i); n = 2, M = Co(i), Rh(i), Ir(i)) complexes

“…33 BP86, a pure GGA functional, was used because it has been widely used for the analysis of the nature of bonds in metal complexes and organometallics. [38][39][40] Vibrational frequency analysis, calculated at both levels of theory, indicates that the optimized structures are at the stationary points corresponding to local minima without any imaginary frequency. The interaction energies for all complexes were calculated at the above-mentioned levels and corrected for the basis set superposition error (BSSE) using the counterpoise (CP) procedure.…”

Bonding in M(NHBMe)2 and M[Mn(CO)5]2 complexes (M=Zn, Cd, Hg; NHBMe=(HCNMe)2B): divalent group 12 metals with zero oxidation state

“…4). This method is found to be excellent to analyze the intriguing bonding situation in several interesting complexes [48][49][50][51][52][53][54][55][56][57].…”

Face‐Centered‐Cubic Ag Nanoclusters: Origins and Consequences of the High Structural Regularity Elucidated by Density Functional Theory Calculations

“…[55][56][57] However,d istinct from the dumb-bell-shaped atomicporbitals, the Po rbitals shown in Figure9a-c all show maximum distribution along the {111} facets, which suggestsb onding to be feasible with the surface motifsa long those facets. Specifically,t he bond critical points [58][59][60][61] (see the light-green points in Figure9aa se xamples) are located at the face and edge centers of the trigonal Ag 3 facet. Therefore, to achieve the most efficient bonding interaction, the exteriors ulfur atoms on the perpendicular line crossingt he midpoint of the AgÀAg bonds and the Ag ext atoms are orientated normalt ot he {111}f acet.…”