Abstract
The bonding interactions such as Fe-Fe, Fe-H and Fe-CO, existing in the iron carbonyl clusters; [(μ-H)2Fe3(CO)9(µ3-As)Mn(CO)5] (1), [Et4N][(µ-H)2Fe3(CO)9(µ3-As)Fe(CO)4] (2) and [Et4N][HAs{Fe2(CO)6(µ-CO)(µ-H)}{Fe(CO)4}] (3), have been studied using atoms in molecules (AIM) approach. Many topological parameters of the electron density for these clusters have been computed at bond critical points (bcp's). The conceptual framework of AIM theory indicates the absence of Fe-Fe direct bonding, since no bond critical point is found between Fe metals and therefore, no bond path connecting them in 1, 2 and 3. Also, from these results, a comparison was done for related but different interactions involving; different Fe…Fe interactions and bridged Fe-H bond versus other bridged Fe-ligand such as Fe-CO. An interaction of (Fe1-H1-Fe2-H2-Fe3) plan existing in each of cluster 1 and 2 is 5c-4e type. While in cluster 3, an interaction core (Fe1-H1-Fe2) is 3c-2e. Finally, the existence of hydride bridging ligands has an efficient role to reduce the electron density delocalized between hydride bridged iron pairs oppositely with hydride unbridged ones.