Photochemistry of tricarbonyl (η5-cyclopentadienyl)(trifluoroacetyl)-molybdenum in a variety of frozen gas matrices at ca. 12 K: infrared spectroscopic evidence for carbon monoxide ejection and difluorocarbene formation by α-F elimination
Abstract
Infrared spectroscopic evidence including 13CO labelling is presented which shows that photolysis of [Mo(η5-C5H5)(CO)3(COCF3)] in frozen gas matrices (argon, methane, carbon monoxide, or nitrogen) at ca. 12 K affords stepwise ejection of CO to yield [Mo(η5-C5H5)(CO)3(CF3)]via the 16-electron species [Mo(η5-C5H5)(CO)2(COCF3)]. Subsequent photolysis of [Mo(η5-C5H5)-(CO)3(CF3)] produces further CO ejection reversibly to give the 16-electron species [Mo(η5- C5H5)-(CO)2(CF3)], which in nitrogen matrices undergoes a reversible reaction to produce cis-[Mo(η5- C5H5)-(CO)2(CF3)(N2)], while in other matrices a novel fluorocarbene species, trans-[Mo(η5- C5H5)-(CO)2(CF2)F], corresponding to α-F elimination is observed for the first time. The mechanisms of the various photolysis steps are discussed in relation to the growing chemistry of metal–halogenocarbene complexes.