119207-87-3Relevant articles and documents
Solution Homolytic Bond Dissociation Energies of Organotransition-Metal Hydrides
Tilset, Mats,Parker, Vernon D.
, p. 6711 - 6717 (1989)
The homolytic bond dissociation energies (BDEs) of the mononuclear metal carbonyl hydride complexes (η5-C5H5)M(CO)3H (M = Cr, Mo, W), (η5-C5Me5)Mo(CO)3H, (η5-C5H5)W(CO)2(PMe3)H, (η5-C5H5)M(CO)2H (M = Fe, Ru), H2Fe(CO)4, Mn(CO)4PPh3H, Mn(CO)5H, Re(CO)5H, and Co(CO)3LH (L = CO, PPh3, P(OPh)3) have been estimated in acetonitrile solution by the use of a thermochemical cycle that reguires knowledge of the metal hydride pKa and the oxidation potential of its conjugate base (anion).The BDE values obtained by this method fall in the range 50-67 kcal/mol.In mostcases, these results agree well with literature data.Our data provide strong support for the common assumption that the M-H bond energies are greater for third-row and for second-row metals than for first-row metals, the difference being 5-11 kcal/mol.Effects of neither phosphine or phosphite substitution nor permethylation of the cyclopentadienyl ring on the M-H bond energies could be detected within the error limits of the method.The results are discussed in relation to previous M-H BDE estimates and metal hydride reactivity patterns.
Reaction of metal carbonyl anions with metal carbonyl dimers: Thermodynamic and kinetic factors that control the reactions
Corraine, M. Shauna,Atwood, Jim D.
, p. 2315 - 2318 (2008/10/08)
The reactions of mononuclear metal carbonyl anions, M- (M- = Co(CO)4-, CpFe(CO)2-, Re(CO)5-, Mn(CO)4L-, L = PPh3, PBu3, P(OPh)3, CpM(CO)3- (M = Cr, Mo, W)) with metal carbonyl dimers, M′2 (M′2 = Co2(CO)8, Cp2Fe2(CO)4, Re2(CO)10, Mn2(CO)10, Cp2M2(CO)6 (M = Cr, Mo, W), and Cp2Ru2(CO)4)), are described: 2M- + M′2 → M2 + 2M′- To determine the thermodynamic parameters, we have derived values for the two-electron-reduction potentials (M2 + 2e- → 2M-) and shown that these values correctly predict the direction of reaction. The order of these reduction potentials is (all are negative) Co2(CO)8 > Cp2Cr2(CO)6 > Cp2Mo2(CO)6 > Mn2(CO)10 > Re2(CO)10 > Cp2Fe2(CO)4. In each case a clean reaction is observed with only M2 and 2M′- produced. The kinetics show that the rate has a first-order dependence on [M-]; rate = k[M-][M′2]. All dimers that contain a cyclopentadienyl ligand react more rapidly than expected from the potential. Product distributions for reactions of heterobimetallic complexes are also consistent with a different mechanism for dimers with a cyclopentadienyl ligand.
Steric and Electronic Factors That Control Two-Electron Processes between Metal Carbonyl Cations and Anions
Zhen, Yueqian,Feighery, William G.,Lai, Chung-Kung,Atwood, Jim D.
, p. 7832 - 7837 (2007/10/02)
Reactions of metal carbonyl cations (Mn(CO)6(+), Re(CO)6(+), Mn(CO)5PPh3(+), Mn(CO)4(PPh3)2(+), Mn(CO)5PEt3(+), Mn(CO)5PPh2Me(+), Re(CO)5PPh3(+), and CpFe(CO)3(+)) with metal carbonyl anions (Co(CO)3PPh3(-), Co(CO)4(-), Mn(CO)5(-), Mn(CO)4PPh3(-), Mn(CO)4PEt3(-), Mn(CO)4PPh2Me(-), Mn(CO)3(PPh3)2(-), CpFe(CO)2(-), Re(CO)5(-), and Re(CO)4PPh3(-)) are reported.Peak potentials are reported for all ions, and nucleophilicites (as measured by reaction with MeI) are reported for the anions.Reaction of any metal carbonyl cation with any metal carbonyl anion leads ultimately to binuclear products, which are the thermodynamic products.The binuclear products are formed by single-electron transfer.In over half of the reactions between metal carbonyl cations and anions, a two-electron change results in a new metal carbonyl cation and anion.The two-electron change may be considered mechanistically as a CO(2+) transfer with the more nucleophilic of the two anions retaining the CO(2+).The kinetic and thermodynamic driving forces and the suggested mechanism are examined.
