Synthesis and characterization of heterometallic complexes involving coinage metals and isoelectronic Fe(CO), [Mn(CO)] and [Fe(CO)CN] ligands.

The chemistry of coinage metal ions with Fe(CO), [Mn(CO)] and [Fe(CO)CN] has been explored using MesP and N-heterocyclic carbene supporting ligands. A comparison of [(SIPr)Au-Fe(CO)][SbF], [(CAAC)Au-Fe(CO)][SbF] and [(MesP)Au-Fe(CO)][SbF] shows that the ligand donor strength towards Au(i) follows the order MesP > CAAC > SIPr. These Fe(CO) complexes show significant blue shifts in [small nu, Greek, macron] bands relative to those observed for free Fe(CO) as a result of it serving as a net electron donor to Au(i). Au(i) is a much stronger acceptor in (SIPr)Au-Mn(CO) compared to Ag(i) in (SIPr)Ag-Mn(CO). The structural details of MesPAu-Mn(CO) are also presented. [Fe(CO)CN] afforded CN bridged coinage metal complexes with (IPr*)Au, (SIPr)Ag and (SIPr)Cu moieties, rather than molecules with direct Fe/coinage metal bonds. The computed total interaction energies indicate that both [Mn(CO)] and [Fe(CO)CN] are stronger donors toward Au(i) than Fe(CO). A detailed analysis of the bonding interactions between the coinage metal ions and Fe(CO), [Mn(CO)] and [Fe(CO)CN] suggests that the largest contribution comes from electrostatic attraction, while the covalent component follows the Dewar-Chatt-Duncanson model. The σ-donor interactions of these organometallic ligands with coinage metal ions are considerably stronger than the π-backbonding from the coinage metal ions.