[{AgL}MoO] complexes: a combined experimental and theoretical study.

Self-assembly reactions between AgNO, L (PPh, PPhPy, AsPh, SbPh) and [β-MoO] in DMF led to the formation of [β-{AgL}MoO] anions, which were isolated as BuN salts (1-4) and characterized by XRD, IR and elemental analysis. In the crystal structures Ag can switch the coordination number from 5 (P, As) to 6 (Sb) by uptake of a DMF molecule. High-level QAIM analysis of the coordination sphere around Ag shows critical points even in the case of longer Ag-O distances. Changing the ligand type to a family of substituted pyridines results in novel Ag-L-POM complexes with different environments around Ag. For 3-X-pyridine ligands (X = Cl, Br, I), complexes with additional DMF molecules [β-{AgL(DMF)}MoO] (5-7) have been isolated. Halogen bonding of the XO type was detected in the crystal structures of 5-7 and studied by DFT calculations, providing estimated energies from 0.9 to 3.4 kcal mol. Variation of substituents at the pyridine ring results in the formation of [β-{AgL}MoO] in the case of 2-NH-py (8), 2-CH-Py (9), 2,4,6-collidine (10) and 2,6-NH-py (11). Solution behavior of 1-4 in CHCN was studied by a hyphenated HPLC-ICP-AES technique. According to the results, the [β-{AgL}MoO] anions are largely dissociated in this medium. An attempt to change the [MoO] precursor to [MoO] (in the case of AgNO and PyPPh) resulted in the crystallization of [Ag(PyPPh)(DMF)][MoO] (12).