40545-09-3Relevant articles and documents
Rapid synthesis of Group VI carbonyl complexes by coupling borohydride catalysis and microwave heating
Birdwhistell, Kurt R.,Schulz, Brian E.,Dizon, Paula M.
, p. 69 - 71 (2013/01/15)
Several Group VI tetracarbonyl phosphine and tertiary amine complexes [M(CO)4 L2, M = Cr, Mo, W, L2 = 2PPh 3, dppm, dppe, dppp, dppb, bpy, phen, dppf] were synthesized in minutes in the microwave at moderate temperature, atmospheric pressure, and utilizing NaBH4 as a catalyst. The reactions were optimized by careful solvent selection. The octahedral complexes were isolated in percent yields ranging from 17 to 95. The lower temperatures, shorter reaction times, benign solvents, and lower pressures as compared to the traditional thermal syntheses provide a rapid, eco-friendly synthetic route to these common Group VI complexes.
Ligand substitution kinetics in M(CO)4(η2:2-norbornadiene) complexes (M=Cr, Mo, W): Displacement of norbornadiene by bis(diphenylphosphino)alkanes
Tekkaya, Aysin,Oezkar, Saim
, p. 208 - 216 (2007/10/03)
The thermal substitution kinetics of norbornadiene (NBD) by bis(diphenylphosphino)alkanes (PP), (C6H5)2P(CH2)nP(C 6H5)2 (n=1, 2, 3) in M(CO)4(η2:2-NBD) complexes (M=Cr, Mo, W), were studied by quantitative FT-IR spectroscopy. The reaction rate exhibits first-order dependence on the concentration of the starting complex, and the observed rate constant depends on the concentration of the leaving NBD ligand and on the concentration and the nature of the entering PP ligand. In the proposed mechanism there are two competing initial steps: an associative reaction involving the attachment of the entering PP ligand to the transition metal center and a dissociative reaction involving the stepwise detachment of the diolefin ligand from the transition metal center. A rate law is derived from the proposed mechanism. The activation parameters are obtained from the evaluation of the kinetic data. It is found that at higher concentrations of the entering ligand, the associative path is dominant, while at lower concentrations the contribution of the dissociative path becomes significant. Both the observed rate constant and the activation parameters show noticeable variation with the chain length of the diphosphine ligand.
Substituted metal carbonyls IV. Studies of the synthesis and decomposition of singly-bridging 1,3-bis(diphenylphosphino)propanedimetal decacarbonyls of chromium, molybdenum and tungsten
Hor, Andy T. S.
, p. 51 - 58 (2007/10/02)
Singly-bridging diphosphine complexes M2(CO)10(μ-dppp) (M=Cr, W; dppp=Ph2P(CH2)3PPh2 have been isolated in a facile synthesis via an oxidative decarbonylation of M(CO)6 using trimethylamine-N-oxide as the initiator.The thermal decomposition of these complexes, together with the molybdenum analogue, have been studied in refluxing acetonitrile, benzene or toluene under N2 or CO.The characterisations and thermal stabilities of these species are described and discussed.Conversion of the 1,3-bis(diphenylphosphino)propanedimetal decacarbonyl complexes of chromium, molybdenum and tungsten into the chelate M(CO)4(η2-dppp) is promoted by free dppp but inhibited by CO gas.
