Reactions of chalcogen oxide chlorides EOCl2 (E = S,Se) with Group 5 metalchlorides

The tantalum derivative TaCl5(SOCl2), thermally unstable above 290 K, was p repared from Ta2Cl10 and SOCl2 and studied by X-ray crystallography at 180 K. Tantalum atom is octahedrally coordinated by five chlorides at Ta-Cl dis tances comprised between 2.32 and 2.36 Angstrom and by the oxygen atom of S OCl2 at the Ta-O distance of 2.34 Angstrom. No evidence for the existence o f an analogous compound of niobium(V) has been obtained. The halides of Gro up 5, M2Cl10, M = Nb, Ta, react with SeOCl2 to give the solid adducts MCl5( SeOCl2) stable at room temperature. The reaction of NbCl5(SeOCl2) with SOCl 2 affords [SeCl3][NbCl6] which contains trigonal-pyramidal (SeCl3)(+) catio ns with Se-Cl distances of 2.13-2.16 Angstrom and octahedral [NbCl6](-) ani ons (Nb-Cl: 2.27-2.45 Angstrom). A distorted octahedral coordination around the selenium atom is achieved by additional interactions [Se . . . Cl, 2.8 1-2.98 Angstrom] between selenium and the [NbCl6](-) anion.