17440-81-2Relevant academic research and scientific papers
Charged states of proteins. Reactions of doubly protonated alkyldiamines with NH3: Solvation or deprotonation. Extension of two proton cases to multiply protonated globular proteins observed in the gas phase
Peschke, Michael,Blades, Arthur,Kebarle, Paul
, p. 11519 - 11530 (2007/10/03)
The apparent gas-phase basicities (GBapp'S) of basic sites in multiply protonated molecules, such as proteins, can be approximately predicted. An approach used by Williams and co-workers was to develop an equation for a diprotonated system, NH
Temperature and Pressure Effects on the Reversible Reaction of a Parent Phenol (GH) Corresponding to Galvinoxyl with Aliphatic Amines
Nishimura, Norio,Iga, Siroh,Satoh, Masahiro,Yamamoto, Shunzo
, p. 2437 - 2441 (2007/10/02)
The effects of temperature and pressure on the reversible reaction between GH and aliphatic amines in acetonitrile have been studied spectrophotometrically.The formation of the free ions rather than that of ion pairs has been confirmed by the modified Benesi-Hildebrand (B-H) plot.From the plot the equilibrium constants were estimated.From the temperature dependence of the equilibrium constant (K), the heat and entropy of reactions were estimated to be: (ΔH0)av=-44.5 kJ mol-1, and (ΔS0)av=-193 J K-1 mol-1.From the pressure dependence of K the reaction volume (ΔV0)av was estimated to be -40 dm3 mol-1.When unbranched primary amines were used, a side reaction took place for which an explanation has been given.
Structure and properties of the hydride-containing cluster ion Pt(H)(PPh3)(AuPPh3)72+
Kanters,Bour,Schlebos,Bosman,Behm,Steggerda,Ito,Pignolet
, p. 2591 - 2594 (2008/10/08)
The title cluster ion can be prepared by the reaction of H2 with Au(PPh3)+ and Pt(PPh3)3 as well as by the reaction of Pt(AuPPh3)82+ with PPh3 and an acid. M?ssbauer spectra show that the central atom is Pt. The structure was determined by X-ray diffraction of Pt(H)(PPh3)(AuPPh3)7(PF6) 2·1/2CH2Cl2 (triclinic, P1, a = 17.085 (6) ?, b = 17.301 (8) ?, c = 29.401 (12) ?, α = 94.62 (10)°, β = 96.26 (5)°, γ = 118.24 (5)°, V = 7523.2 ?3, Z = 2, R = 0.085 and Rw = 0.115 for 15921 unique reflections and 596 variables, Cu Kα radiation). In the metal cluster the central Pt is surrounded by seven Au atoms and one PPh3 in a distorted cubic geometry, each Au being attached to a PPh3. The H is close to Pt and at least two Au atoms, as can be concluded from deformations in the metal frame and from Orpen calculations. Detailed 31P, 195Pt, and 1H NMR spectra are presented. The different Au-PPh3 sites, present in the crystal, are equilibrated in solution at room temperature.
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.
Kinetic and Equilibrium Solvent Isotope Effects on the Deprotonation of a Salicylate Ion by Hydroxide Ion and General Bases
Hibbert, Frank
, p. 1304 - 1308 (2007/10/02)
Kinetic and equilibrium solvent isotope effects has been measured for proton transfer from 4-(3-nitrophenylazo)-salicylate ion (HA) to general bases (B) to examine whether a primary kinetic isotope effect is observed when proton transfer is occurring between bases of roughly equal strength for which ΔpK = pKHA - pKBH(1+) = 0.The kinetic solvent isotope effects for catalysis by three tertiary amines (ΔpK -0.85, -0.27, and +0.28) are kBH2O/kBD2O 2.0 +/-0.3, and 1.7 +/-0.2.Since for proton transfer to hydroxide ion (ΔpK -5.0) the isotope effect has a value kOH(1-)H2O(1-)/kOD(1-)D2O of 1.5 +/-0.1, the primary isotope effect for these proton transfers must be small and independent of base strength over the range studied.An explanation in terms of the reaction mechanisms is given.
Rates of Reaction in the p-Nitrophemol-Triethylamine System in Acetonitrile
Marshall, David B.,Strohbusch, Frank,Eyring, Edward M.
, p. 2270 - 2273 (2007/10/02)
The rate constants of proton transfer between p-nitrophenol (AH) and triethylamine (B) in acetonitrile (ionic strength μ1.3E-4 M, 25.0 deg C) were measured by the electric field jump relaxation method with spectrophotometric detection.This acid-base syst
