Rates of hydride abstraction from amines via reactions with ground-state silver(+) and copper(+)

Hydride abstraction of methylamine with Cu+(1S) in the gas phase: A density functional theory study

“…This product is calculated to be 72.2 kcal mol À1 higher in energy than its CT counterpart (5), in good agreement with the energy difference between 5 0 and 5 (74 kcal mol À1 ) estimated with the ionization potentials of CH 2 NH 2 ($6.3 eV) [18,37] and CuH ($9.5 eV) [36]. It is this large energy difference that dictates CH 2 NH 2 + + CuH (5) rather than CH 2 NH 2 + CuH + (5 0 ) to be the product of Cu + reaction with CH 3 NH 2 as observed in the experiment [13].…”

“…It is this rather strong Cu + -methylamine association that explains the reaction of Cu + + CH 3 NH 2 ! CuH + CH 2 NH 2 + as observed at thermal energy [13]. It is important to note that for the complex, in spite of the above-mentioned electron transfer, the positive charge is still centralized mainly on the metal center due to a back-donation of part of charge to the higher electronegative N atom from the metal [22].…”

“…This reaction is a fast bimolecular reaction established by the measurement of the reaction rate (2.1 · 10 À9 cm 3 s À1 ) and based on the experimental results and their implications a qualitative reaction mechanism has already been discussed [13]. Our objective of this work is to bridge the gap between experiments and theories for this type of reaction.…”

“…Because of its unique importance in the global nitrogen cycle, biology processes, and organic syntheses [1][2][3][4][5][6][7][8], over the past two decades, the gas-phase reactivity of amines with metal ions has been investigated by a great body of studies, wherein hydride abstraction leading to metal hydride and hydride-abstracted amine ions is always a substantial, if not a major, reaction channel [9][10][11][12][13][14][15][16]. For instance, Radecki and Allison have reported that Co + abstracts a hydride unit from amines to form CoH whenever there is an a-hydrogen available but not when there is no a-hydrogen [10].…”

“…Armentrout et al have experimentally studied the kinetic energy dependence of the endothermic hydride abstraction reactions of M + (M = V, Cr, and Ti) with methyl-substituted amines (methylamine, dimethylamine, and trimethylamine) and obtained the first experimental measurement of gas-phase bond dissociation energies for the corresponding transition metal hydrides [11,12]. Furthermore, rates for the hydride abstraction from methyl-substituted amines via reaction with Ag + and Cu + have been measured in all cases except for Ag + with methylamine in a flow reactor at ambient room temperature [13]. On the other hand, hydride abstraction has also been found to be an extensive reaction channel in the photodissociation of Mg + -amine complexes [14][15][16].…”