Group 6 Hexacarbonyls As Ligands for the Silver Cation: Syntheses, Characterization, and Analysis of the Bonding Compared with the Isoelectronic Group 5 Hexacarbonylates

The syntheses of the two novel complexes [Ag{Mo/W(CO) } ] [F-{Al(OR ) } ] (R =C(CF ) ) are reported along with their structural and spectroscopic characterization. The X-ray structure shows that three carbonyl ligands from each M(CO) fragment bend towards the silver atom within binding Ag-C distance range. DFT calculations of the free cations [Ag{M(CO) } ] (M=Cr, Mo, W) in the electronic singlet state give equilibrium structures with C symmetry with two bridging carbonyl groups from each hexacarbonyl ligand. Similar structures with C symmetry (M=Nb) and D symmetry (M=V, Ta) are calculated for the isoelectronic group 5 anions [Ag{M(CO) } ] (M=V, Nb, Ta). The electronic structure of the cations is analyzed with the QTAIM and EDA-NOCV methods, which provide detailed information about the nature of the chemical bonds between Ag and the {M(CO) } (q = -2, M = V, Nb, Ta; q = 0, M = Cr, Mo, W) ligands.