102209-55-2Relevant academic research and scientific papers
Characterization of mer,mer-{Cr(CO)3(η2-dpe)}2(μ-dpe) (dpe = Ph2PCH2CH2PPh2) and an investigation of its chemical, redox, and photochemical reactivity
Bond, Alan M.,Colton, Ray,Cooper, John B.,McGregor, Katherine,Walter, Jacky N.,Way, David M.
, p. 49 - 56 (2008/10/08)
Reaction of (C7H8)Cr(CO)3 with dpe (dpe = Ph2PCH2CH2PPh2) in refluxing hexane gives mer,mer-{Cr(CO)3(η2-dpe)}2(μ-dpe) instead of the expected mer-Cr(CO)3(η1-dpe)(η2-dpe). The dinuclear species has been characterized by 31P NMR and IR spectroscopies, elemental analysis, and voltammetry which shows two closely spaced reversible one-electron oxidation processes at about 75 and 225 mV vs Ag/AgCl due to the reactions {Cr(CO)3(η2-dpe)}2(μ-dpe) ? [{Cr(CO)3(η2-dpe)}2(μ-dpe)]+ + e- and [{Cr(CO)3(η2-dpe)}2(μ-dpe)]+ ? [{Cr(CO)3(η2-dpe)}2(μ-dpe)]2+ + e-. On the synthetic time scale at -78°C the mer,mer-[{Cr(CO)3(η2-dpe)}2(μ-dpe)] + cation is moderately stable whereas the mer,mer-[{Cr(CO)3(η2-dpe)}2(μ-dpe)] 2+ cation is completely unstable. The decomposition reactions of mer,mer-{Cr(CO)3(η2-dpe)}2(μ-dpe) have been studied in the dark and in the presence of light to give novel and distinctively different decomposition pathways. In the light, photochemical oxidation of mer,mer-{Cr(CO)3(η2-dpe)}2(μ-dpe) occurs to generate mer,mer-[{Cr(CO)3(η2-dpe)}2(μ-dpe)] +, which then decomposes to give several products, among which mer-[Cr(CO)3(η1-dpe)(η2-dpe)] +, trans[Cr(CO)2(dpe)2]+, and Cr(CO)4(dpe) have been identified. In the dark, mer-Cr(CO)3(η1-dpe)(η2-dpe) is a decomposition product. In the presence of an external oxidant such as NO+ or an electrode, mer-[Cr(CO)3(η1-dpe)(η2-dpe)] + is a product. Evidence for these products is gained by voltammetric and spectroscopic studies.
Substitution and addition reactions of the (CO)3(η7-tropylium)M cations (M = Cr, Mo, W) with tertiary diphosphines
Brown, David A.,Burns, John,Glass, William K.,Cunningham, Desmond,Higgins, Tim,McArdle, Patrick,Salama, Mabrouk M.
, p. 2662 - 2667 (2008/10/08)
The reactions of the title compounds I-III, [(η7-C7H7)M(CO)3]BF4 (M = Cr, Mo, and W, respectively), with the diphosphines PPh2(CH2)nPPh2 (n = 1-4) at low temperatures (-40 to -60°C) form two new series of complexes which are quite different from previous carbonyl substitution products. The first series (IV-VI) formed by the diphosphines (n = 1-3) comprise 7-exo ring adducts involving the bonding of only one phosphorus atom of the diphosphine to ring carbon atom 7 of I. The second series (VII and VIII) are diphosphine ring linked dimers, e.g. [(7,7′-exo-dppb){η6-C7H7)Cr(CO) 3}2] [BF4]2, for which X-ray crystallography confirms a diphosphine linked ring-ring structure with the Cr(CO)3 moieties situated on opposite sides of the ring systems. The ring C-phosphorus bond length of 1.852 A? indicates a relatively weak bond, consistent with facile cleavage of these adducts on reaction with nucleophiles such as hydride.
