RT Journal Article
T1 Oxidative addition of the N−H bond of ammonia to iridiumbis(phosphane) complexes: A combined experimental andtheoretical study
A1 Betoré, M. Pilar
A1 Casado González, Miguel Ángel
A1 García Orduña, Pilar
A1 Lahoz, Fernando J.
A1 Polo, Víctor
A1 Oro, Luis A.
AB The chloro complex [IrCl(cod)(dppe)] (dppe = bis-(diphenylphosphane)ethane; cod = 1,5-cyclooctadiene) was found to react with gaseous ammonia, affording the amido-bridged diiridium complex [{Ir(μ-NH2)H(dppe)(NH3)}2][Cl]2 (1), whose molecular structure has been solved by X-ray methods. The related cationic complexes [{Ir(μ-NH2)H(dppp)(NH3)}2][BF4]2 (3) and [{Ir(μ-NH2)-H(dppb)(NH3)}2][BF4]2 (4) (dppp = bis(diphenylphosphane)propane; dppb = bis(diphenylphosphane)butane) are only accessible from the reactions of NH3(g) with the cationic starting materials [Ir(cod)(dppp)]-[BF4] and [Ir(cod)(dppb)][BF4], respectively. The formation of these species comes from an oxidative addition of an N−H bond of ammonia to the metals. The main structural difference between complex 2 and 3/4 relies on the relative stereochemistry of both ammonia and hydrido ligands; their cisoidal disposition in dppe complex [{Ir(μ-NH2)H(dppe)(NH3)}2][BF4]2 (2) directed the reactivity toward dppm (dppm = bis(diphenylphosphane)methane), generating the triply bridged amido complex [{Ir2(μ-NH2)2(μ-dppm)H2(dppe)2]-[BF4]2 (5). DFT calculations show that the reaction between [IrCl(cod)(dmpe)] (dmpe = bis(dimethylphosphane)ethane) and NH3 to yield complex [{Ir(μ-NH2)H(dmpe)(NH3)}2][Cl]2 comprises four steps: (i) formation of the cationic complex, (ii) replacement of the cod ligand by ammonia molecules, (iii) oxidative addition of the N−H bond to the metal, and (iv) dimerization of the resulting Ir(III) intermediate, step (iii) being the rate-determining one. The calculations reveal that the N−H bond activation takes place heterolytically through an ammonia-assisted stepwise pathway, instead of a concerted homolytic N−H bond cleavage and hydrido formation through a classical three-center transition structure.
PB ACS Publications
SN 0276-7333
YR 2016
FD 2016-03-02
LK https://hdl.handle.net/20.500.14352/23103
UL https://hdl.handle.net/20.500.14352/23103
LA eng
NO Ministerio de Economía y Competitividad (MINECO)/ FEDER
NO DGA/FSE (group E07)
DS Docta Complutense
RD 17 abr 2025