VIBRATIONAL ANALYSIS OF THE P7(3-), AS7(3-), AND SB7(3-) CAGE-LIKE (C3(V)) ANIONS BASED ON SCALED QUANTUM-MECHANICAL (SQM) CALCULATIONS ON P7(3-)

A scaled quantum mechanical (SQM) vibrational analysis at the 6-31G/S CF level was performed for P-7(3-). The force field was transferred to the isostructural homologues As-7(3-) and Sb-7(3-) and rescaled with two parameters. For As-7(3-) and Sb-7(3-) the calculations confirm an earlier assignment of the vibrational spectra, whereas for P-7(3-) som e bands are reassigned. Transfer of a 6-31G/SCF force field from the isostructural and isoelectronic molecule P4S3 to P-7(3-) confirms the revised assignments. The mechanism of the valence tautomerism in P-7(3 -) is also verified.