A complex Ar•••Ag-I produced by laser ablation and characterised by rotational spectroscopy and ab initio calculations: Variation of properties along the series Ar•••Ag-X (X = F, Cl, Br and I)

A complex of argon with silver iodide (Ar center dot center dot center dot Ag-I) has been formed in the gas phase by laser ablation of a silver iodide rod in the presence of a pulse of argon gas and its ground-state rotational spectrum has been detected by means of a chirped-pulse, F-T microwave instrument. Ar center dot center dot center dot Ag-I was characterised both by experimental properties determined from its rotational spectrum and by ab initio calculations carried out at the CCSD(T)(F12c)/cc-pVTZ-F12 explicitly correlated level of theory. The molecule was shown to be linear in the ground state, with atoms in the order shown. The Ar center dot center dot center dot Ag and Ag-I bond lengths ro(Ar center dot center dot center dot Ag) = 2.6759 angstrom and r(0)(Ag-I) = 2.5356 angstrom, the dissociation energy D-e = 16.7 kJ mol(-1) for the process Ar center dot center dot center dot Ag-I = Ar + Ag-I, the intermolecular quadratic stretching force constant F-Ar center dot center dot Ag = F-22 = 20.2(8) N m(-1) and the increase 0.033 in the ionicity i(c) of Ag-I when it enters the complex are reported. The opportunity has been taken to compare the way in which these properties vary along the series Ar center dot center dot center dot Ag-X (X = F, Cl, Br and I). (C) 2017 Elsevier Inc. All rights reserved.