Infrared and Raman spectra of Cs2VOP2O7 and single crystal Rb-2(VO)(3)(P2O7)(2)

Infrared (IR) and Raman spectra of Cs2VOP2O7 and single crystal Rb-2(VO)(3) (P2O7)(2) have been recorded and analysed. The spectra are interpreted on t he basis of P2O74- and VO vibrations. The appearance of v(s)P-O-P in both R aman and IR spectra suggests a bent POP bridge for the P2O74- ions in both compounds, in agreement with X-ray data. The observed bands point to an ecl ipsed configuration for the P2O74- ions with C-2v symmetry in Rb-2(VO)(3)(P 2O7)(2). The appearance of P-O stretching modes in Cs2VOP2O7 at higher wave mumbers than those in Rb-2(VO)(3)(P2O7)(2) indicates that the P-O bonds in the Cs compound is stronger than in the Rb compound. VO modes are also inte rpreted. (C) 1999 Elsevier Science B.V. All rights reserved.