Photochemistry of cyclopentadienylmolybdenum and cyclopentadienyltungsten carbonyl halide complexes

The photochemistry of cylopentadienylmolybdenum complexes including the mechanism of the cis-trans photoisomerism of (η5-C5H5)Mo(CO)2LX, X = Cl Br, I; L = PPh3, PBu3

“…Our results indicate that CO loss, according to reaction [3], is the only observable process upon photolysis of (q5-C5H5)Mo(C0)2PR3X at 12 K. This finding is consistent with a recently published report of the photochemistry of (q5-C5H5)Mo(C0)3Cl which was found to undergo CO loss in inert gas matrices at 12 K (5).…”

“…Previous reports indicated that molybdenum phosphine complexes of the type ( r 1 5 -C 5 H 5 ) M o (~0 ) 2~~3 X undergo a photoinduced isomerism (3). The reaction, given by reaction [2], is a geometrical isomerism of the basal ligands.…”

Oxidation of [CpMo(CO)3R] olefin epoxidation precatalysts with tert-butylhydroperoxide

“…complex 5 in this work and R = CF 3 [24]) relative to other examples (such as [CpMo(CO) 3 Cl]) and thus their lower TOFs in epoxidation reaction, must be a consequence of the rate limiting step involving initial loss of one CO group. This has been previously described for photo-induced decarbonylation by Barnett and Alway [74]. Ligand stereoelectronic effects and the apparent stereochemical rigidity of the organometallic molecule can negatively influence this rate, if there is a hindrance to attaining the appropriate 'electronic situation' or geometry for reaction with TBHP.…”

Photochemistry of (η3-allyl)Ru(CO)3X Precursors for Photoassisted Chemical Vapor Deposition

“…Previous studies have shown that halogen loss is not likely to be a competing photoprocess. 17,18 Previous studies with CpM(CO) 3 X (M = W, Mo) 17 and CpFe(CO) 2 X 18 have suggested a general trend of a decreasing quantum yield for CO substitution for complexes of the lower row halides, so that Φ Cl > Φ Br > Φ I . It should be noted that for certain comparisons (CpFe(CO) 2 X where X = Br, I 18 and CpW(CO) 3 X where X = Cl, Br 17 ), the differences in the reported quantum yields are not greater than that of the range of the reported errors.…”

“…17,18 Previous studies with CpM(CO) 3 X (M = W, Mo) 17 and CpFe(CO) 2 X 18 have suggested a general trend of a decreasing quantum yield for CO substitution for complexes of the lower row halides, so that Φ Cl > Φ Br > Φ I . It should be noted that for certain comparisons (CpFe(CO) 2 X where X = Br, I 18 and CpW(CO) 3 X where X = Cl, Br 17 ), the differences in the reported quantum yields are not greater than that of the range of the reported errors. However, the quantum yields obtained for the −Br and −I derivatives of CpM(CO) 3 X (M = W, Mo) are significantly different with respect to error and a generalized trend of Φ Br > Φ I is supported by the data.…”