Concerning isomerisms and interconversions of 2 : 18 and 2 : 17 heteropoly complexes and their derivatives

Abstract

Contrary to recent interpretations, it is demonstrated by ¹⁸³W n.m.r. and by V^IV e.s.r. spectroscopy that: (i) the α₂ isomer of [(PO₄)₂W₁₇O₅₃]^10–, and its α₂[(PO₄)₂VW₁₇O₅₄]^8– derivative, differ from α-[PO₄)₂W₁₈-O₅₄]^6– by absence of a W atom from one of the 3-fold W₃O₁₃ groups which cap the ends of the latter complex, rather than by removal or substitution of one W atom from the 12 which are around the complex's ‘belt’; and (ii)β-[(PO₄)₂W₁₈O₅₄]^6– differs from its α isomer by a 60° rotation, about its 3-fold axis, of one of the ‘cap’ W₃O₁₃ groups rather than by a 60° rotation of one PW₉‘half-unit’ relative to the other one.