Synthesis, characterization, crystal structure and hybrid DFT computation of the chlorooxoarsenate(III), [NMe4](2)[AS(4)O(2)Cl(10)] center dot 2 CH3CN

[NMe4](2)[AS(4)O(2)Cl(10)] . 2CH(3)CN was recovered by the reaction of [NMe 4][N-3] with AsCl3 in CH3CN under aerobic conditions. This compound was als o obtained directly by the reaction of AsCl3, As2O3 and [NMe4][Cl] in aceto nitrile. The structure was determined by X-ray diffraction. [NMe4](2)[As4O2 Cl10] . 2 CH3CN crystallizes in the orthorhombic space group Fmmm with a = 11.4144(8), b = 14.732(1) and c = 19.803(2) Angstrom, with 4 formula units per unit cell. The frequencies obtained by Raman and infrared spectroscopy were assigned to the normal modes of the normal modes of the [AS(4)O(2)Cl(1 0)](2-) anion in comparison with computational results. The bonding situati on in the [As4O2Cl10](2-) anion was elucidated on the basis of an NBO analy sis on the crystallographic data.