THE LOW-TEMPERATURE PHOTOCHEMISTRY OF (NU-5-C5H5)M(CO)3X (M-EQUIVALENT-TO-MO, W, X-EQUIVALENT-TO-CL, BR, I) - STRUCTURE AND SOLVATION OF THE CO LOSS PRODUCTS

The complexes (eta5-C5H5)M(CO)3X (M = Mo, W; X = Cl, Br, I) all underg o photochemical loss of CO at 12 K in a styrene oxide glass. The produ ct in each case is (eta5-C5H5)M(CO)2SX Where S represents solvation by the glass. Each of the unsaturated species undergoes thermal reaction with CO to form (eta5-C5H5)M(CO)3X upon warming. Prolonged photolysis of (eta5-C5H5)W(CO)2SI leads to the loss of a second molecule of CO a nd the formation of a monocarbonyl species. The nature of the solvatio n of the unsaturated species (eta5-C5H5)M(CO)2SX has been investigated by applying Timney's method to analyse the spectra of these complexes . The ligand effect constants have been refined for a variety of ligan ds from a set of 85 four-legged piano-stool molecules with molybdenum, tungsten, vanadium and rhenium as the central metals. Using the deriv ed constants, the styrene oxide was found to be coordinated through th e oxygen atom in most cases, leading to the general formulation of the photoproducts as (eta5-C5H5)M(CO)2(OCH2CHPh)X (M = Mo; X = Cl, I) (M = W; X = Cl, Br, I). In one case, namely (eta5-C5H5)Mo(CO)2(eta2-PhCHC H2O)Br, the styrene oxide appears to be coordinated through the phenyl ring.