Closed-shell and open-shell square-planar iridium nitrido complexes

Abstract

Coupling reactions of nitrogen atoms represent elementary steps to many important heterogeneously catalysed reactions, such as the Haber-Bosch process or the selective catalytic reduction of NO(x) to give N(2). For molecular nitrido (and related oxo) complexes, it is well established that the intrinsic reactivity, for example nucleophilicity or electrophilicity of the nitrido (or oxo) ligand, can be attributed to M-N (M-O) ground-state bonding. In recent years, nitrogen (oxygen)-centred radical reactivity was ascribed to the possible redox non-innocence of nitrido (oxo) ligands. However, unequivocal spectroscopic characterization of such transient nitridyl {M=N(•)} (or oxyl {M-O(•)}) complexes remained elusive. Here we describe the synthesis and characterization of the novel, closed-shell and open-shell square-planar iridium nitrido complexes [IrN(L(t-Bu))](+) and [IrN(L(t-Bu))] (L(t-Bu)=N(CHCHP-t-Bu(2))(2)). Spectroscopic characterization and quantum chemical calculations for [IrN(L(t-Bu))] indicate a considerable nitridyl, {Ir=N(•)}, radical character. The clean formation of Ir(I)-N(2) complexes via binuclear coupling is rationalized in terms of nitrido redox non-innocence in [IrN(L(t-Bu))].

[IrCl{N(CHCHPtBu2)2}]−: a versatile source of the IrI(PNP) pincer platform

“…[Ir(N 2 ){N(CHCHPtBu 2 ) 2 }] (5, δ( 31 P) = 70.3 ppm) is identified as the main product (61%). 15 [Ir(H)(C 6 H 5 ){N(CHCHPtBu 2 ) 2 }] (6). A solution of 1 (30.0 mg; 51.4 µmol; 1 eq.)…”

Trapping of an NiII Sulfide by a CoI Fulvene Complex

“…[7][8][9][10][11][12][13][14][15][16][17][18] While a few of these complexes have been isolated, they tend to be extremely reactive, and often can only be observed spectroscopically. [19][20][21][22] Nonetheless, it is clear that synthetic chemists are now beginning to identify the combination of ligand requirements and synthetic procedures that can successfully generate late-metal ligand multiple bonds.…”

Formation of a Stannyl Amido Complex by the Reaction of a Terminal Iridium Nitrido Complex with a Stannane

“…Recent reports evidenced the potential of isolated and putative nitrido complexes in intramolecular C-H [11] and dihydrogen [7,8] activation. Further prominent reactions include an hydrogen atom abstraction, [12] the dimerization to dinitrogen complexes, [13] nitrogen transfer, [14,15] and the reactions with the nucleophiles Me 3 NO [8,10] and Ph 3 P. [4,15] For the later reaction Smith et al have recently shown, that both, electron donation to and from the nitrido nitrogen atom take place in the transition state. [16] Recently, we have shown that square-planar iridium complexes with a terminal nitrido unit also react with silanes under insertion of the nitrido nitrogen atom into the Si-H bond.…”

“…[1] Isolated examples of low valent late transition metal complexes with terminal nitrido ligands, however, still remain rare [2] due to destabilizing electron interactions between the electron rich central metal atoms and the strong π-donor ligand. [3] Besides some pseudo tetrahedral iron complexes with a terminal nitrido unit, [4,5] there are pseudo square-planar ruthenium [6,7] and iridium [8][9][10] complexes known. Recent reports evidenced the potential of isolated and putative nitrido complexes in intramolecular C-H [11] and dihydrogen [7,8] activation.…”