C-N coupling in the gas-phase reactions of ammonia and [M(CH)]+ (M = Ni, Pd, Pt): a combined experimental/computational exercise.
Electrospray ionization (ESI) of methanolic solutions of monomeric nickel(II) acetate, [Ni(CH(3)COO)(2)], and tetrameric platinum(II) acetate, [Pt(4)(CH(3)COO)(8)], leads to the formation of the corresponding methylidyne complexes [M(CH)](+) (M = Ni, Pt), which react with ammonia under C-N coupling. While the product couples M/[CH(4)N](+) and [M(CH(2)N)](+)/H(2) are observed for both metals, hydrogen-atom expulsion to generate [M(CHNH(2))](+)/H is only observed in the case of the nickel-containing system, and the proton transfer leading to M/[NH(4)](+) is limited to platinum. Attempts to conduct related experiments with [Pd(CH)](+)/NH(3) failed. The mechanisms that explain the experimentally observed reaction channels have been investigated computationally using the B3LYP functional for all metals of the nickel group (M = Ni, Pd, Pt). In line with labeling experiments using the reaction pairs [M(CD)](+)/NH(3) and [M(CH)](+)/ND(3) (M = Ni, Pt), two different mechanistic scenarios of the dehydrogenation process are operative for the Ni and Pt systems, respectively.
Technische Universität Berlin, Institut für Chemie, Strasse des 17.Juni 115, 10623 Berlin, Germany.
Robert
R
Kretschmer
Maria
M
Schlangen
Helmut
H
Schwarz
D000641:Ammonia / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics
D056831:Coordination Complexes; D005740:Gases; D010984:Platinum; D010165:Palladium; D002244:Carbon; D000641:Ammonia; D009532:Nickel; D009584:Nitrogen