The characterisation of alkali metal phosphites,arsenites and antimonites

Infrared spectra have been obtained for the molecular species MPO₂, MAsO₂ and MSbO₂ (M = alkali metal) isolated in nitrogen matrices and three of these are characterised in detail. In NaPO₂ fundamentals are observed at 1151.6 (ν PO), 1062.1 (ν PO) and 523.0 (δ PO₂) cm^?1 whilst in CsAsO₂ and KSbO₂ corresponding modes are observed at 863.0, 851.5 and 393.0 cm^?1 and at 764.6, 744.9 and 339.0 cm^?1. ¹⁸O enrichment experiments indicate C_2v ring structures for all three MXO₂ species and bond angles were estimated as OPO = 114°, OAsO = 115° and OSbO = 106°.