Qualitatively Different Reactivities of Hydride Reagents toward [(α-diimine)(η⁵-C₅Me₅)ClIr]⁺ Cations:  Substitution, Electron Transfer (Reduction), or Stepwise Hydrogenation

Abstract

Me 5 )ClIr] + with 2,2′-bipyridine and related aromatic ligands show only the expected Cl/H exchange on reaction with borohydrides, the systems [(RNdCHCHd NR)(η 5 -C 5 Me 5 )ClIr] + undergo reduction to the enediamido(2-)-iridium(III) species [(RNCHdCHNR)(η 5 -C 5 -Me 5 )Ir], even in protic media, if R is an axially shielding 2,6-dialkylphenyl group. In protic media the complex ion with R ) cyclohexyl undergoes Cl/H exchange and stepwise hydrogenation of the R-diimine ligand via [(RHNCH 2 CHdNR)(η 5 -C 5 Me 5 )HIr](PF 6 ) to the structurally characterized compound [(RHNCH 2 CH 2 NHR)(η 5 -C 5 Me 5 )HIr][BH 3 (CN)].

The 1,4-diazabutadiene/1,2-enediamido non-innocent ligand system in the formation of iridaheteroaromatic compounds: Spectroelectrochemistry and electronic structure

“…The confirmed (vide infra) reduction of the ligand instead of the metal through the hydride reagent may involve an intraligand electron transfer because the primary hydride attack is believed to occur at the Ir-Cl site of the precursor 1 [26].…”

“…Mononuclear compounds with E-E = 1,4-diazabutadiene were among the investigated examples [11,21,23,26], however, a detailed (spectro)electrochemical analysis and an electronic description of intermediates were lacking. Following a recent report on the redox-switched dissociative oxidation of H 2 by the semiquinone form 3 + of the analogue with E-E = N-(2-trifluoromethylphenyl)-4,6-di-tert-butyl-iminobenzosemiquinone [27] we have undertaken experimental and theoretical studies in order to obtain a clearer insight into the structurally characterized [21] systems 1 and 2 (Scheme 1).…”

The Manifold Structural Chemistry of Alkali Metal Enediamide Complexes

“…Well-investigated enediamide-type DAD complexes have been reported mainly for the rare earth [6][7][8][9][10][11][12][13][14][15] and early transition metals, particularly comprising Group IV and Group V metals, [16][17][18][19][20][21][22][23][24][25] although a few late transition metal enediamide complexes have been reported. [26,27] An ytterbium(III) enediamide compound has recently been shown to behave as single-ion magnet, [14] while several Group IV enediamide complexes have been shown to be promising homogeneous catalysts e.g. for olefin polymerization [23] and the ring-opening polymerization of cyclic esters.…”

N,N′-Dicyclohexylethylenediammonium dichloride

“…For the crystal structures of cyclohexylammonium derivatives, see Smith et al (1994); Martell & Zaworotko (1991). For the crystal structure of an iridium complex with the N,N 0dicyclohexylethylenediamine ligand, see: Greulich et al (2002). For a review of hydrogen bonding, see Steiner (2002).…”