MO2F4(PR3)4 COMPOUNDS AND A COMPARISON OF THEIR PROPERTIES WITH THOSE OF OTHER MO2X4(PR3)4 COMPOUNDS - A NEW SYNTHETIC ROUTE TO METAL FLUORIDES BY THE REACTION OF ALKYL SPECIES WITH OLAH REAGENT

The syntheses of Mo2F4(PMe3)4 (1) and Mo2F4(PMe2Ph)4 (2) from the reaction of Mo2Me4(PR3)4 with Olah's reagent (py.xHF) proceed in high yields with the liberation of methane gas. Compound 1 crystallizes in space group I43mBAR, with a = 10.8138 (4) angstrom, V = 1264.5 (2) angstrom 3, and Z = 2. The molybdenum atoms are disordered over three positions; principal bond distances are Mo(1)-Mo(1)' = 2.110 (5) angstrom, Mo(1)-P(1) = 2.444 (3) angstrom, and Mo(1)-F(1) = 2.105 (2) angstrom. The new compounds have been characterized by NMR and other spectroscopies, and the properties of 1 have been compared with those of the previously reported Mo2X4(PMe3)4 (X = Cl, Br, I) compounds. Correlations have been found among various physical properties: delta-delta* and LMCT transitions; Mo-X distances and ionic volume of the halides; atomic number of the halides and NMR shifts.