Synthesis,mass spectra,raman and infrared spectra of the compounds M(PF3)6 (M = Cr,Mo, W)

An improved method of synthesis of hexakis(trifluorophosphine)chromium(0), -molybdenum(0)and -tungsten(0) is described, involving photochemically induced substituion of carbonyl groups from the (trifluorophosphine)tricarbonylmetallates by PF₃ under moderate pressure. A full analysis of the fragmentation patterns in a mass spectrometer is given, and both Raman and infrared data obtained throughoutthe range 4000–50 cm^?1 are discussed. Complete vibrational mode assignments are made, and a normal coordinate analysis leading to the determination of force constants and potential energy distributions is presented. The normal mode in which M-P bond stretching is predominant in all cases involves a significant contribution from PF bond stretching in these molecules.