90143-30-9Relevant academic research and scientific papers
Gas-Phase Chemistry of Transition Metal-Imido and -Nitrene Ion Complexes. Oxidative Addition of N-H Bonds in NH3 and Transfer of NH from a Metal Center to an Alkene
Buckner, Steven W.,Gord, James R.,Freiser Ben S.
, p. 6606 - 6612 (2007/10/02)
We report here on the gas-phase chemistry of a number of bare transition metal-nitrene and -imido ion complexes, MNH+.Group 3, 4, and 5 atomic metal ions react with NH3 at thermal energies to generate MNH+ via dehydrogenation.A reaction mechanism is proposed involving initial oxidative addition to an N-H bond, in analogy to mechanisms proposed for reactions of gaseous atomic metal ions with hydrocarbons.Cr+ reacts with NH3 via slow condensation to form CrNH3+, as do all group 6-11 atomic metal ions investigated.However, excited-state Cr+ reacts with NH3 via bond-insertion reactions to form CrNH2+ and CrNH+.An unidentified metastable electronic state of Cr+, produced by direct laser desorption of chromium foil, reats with much higher efficiency than does kinetically excited Cr+.FeO+ reacts with NH3 to generate FeNH+ with loss of H2O.Thermochemical studies of VNH+ and FeNH+ involving ion-molecule reactions indicate values of D0(V+-NH) = 101 +/- 7 kcal/mol and D0(Fe+-NH) = 54 +/- 14 kcal/mol, the latter value in accord with D0(Fe+-NH) = 61 +/- 5 kcal/mol obtained from photodissociation.The high bond strength for VNH+ indicates multiple bonding, analogous to that in the isoelectronic VO+, while the weaker bond strength for FeNH+ indicates a single bond, analogous to that in the isoelectronic FeO+.Proton-transfer experiments indicate PA(VN) = 220 +/- 4 kcal/mol from which ΔHf(VN) = 111 +/- 9 kcal/mol and D0(V-N) = 125 +/- 9 kcal/mol are obtained.VNH+ is unreactive with ethene and benzene, but FeNH+ transfers NH to ethene and benzene through metathesis and homologation reactions.A cyclic metalloaminobutane intermediate is consistent with the products of the FeNH+/ethene reaction.
Reactions of FeCH2(1+) and CoCH2(1+) with Olefins in the Gas Phase. Studies Involving Olefin Metathesis
Jacobson, D. B.,Freiser, B. S.
, p. 2605 - 2612 (2007/10/02)
Reactions of the title carbenes with several olefins and alkynes are reported.Ethene reacts with MCH2(1+) yielding exclusively M(1+) formation (C3H6 elimination).Reaction of ethene with MCD2(1+) yields the metathesis products FeCH2(1+) and CoCH2(1+) in 20percent and 2percent yields, respectively.Formation of the metathesis product MC2H4(1+) dominates for propene with no MCH2(1+) produced from MCD2(1+).Formation of MC2H4(1+) is believed to proceed through an ethene-ethylidene intermediate that rearranges to a bis(ethene) complex followed by elimination of ethene.Absence of MCH2(1+) formation from reaction of MCD2(1+) with propene suggests that the alkene-alkylidene conversion is the key step in metathesis of olefins larger than ethene.Several other pathways compete with metathesis such as cyclopropanation, olefin homologation, dehydrogenation, and various C-C bond cleavages.Both carbenes react with butadiene, generating M-c-C5H6(1+) and M-c-C5H5(1+), implying D0(Co(1+)-C5H5) > 76+/- 7 kcal/mol and D0(Fe(1+)-C5H5) > 87 +/- 5 kcal/mol.Finally, ethyne and propyne react with MCH2(1+) to yield M(1+) as the only product.
