28 research outputs found
Synthesis and Structure Determinations of Complexes Containing a Five-Membered Lactam Structure Based on Organohydrazido(2−) Ligands 1
No full textSynthesis of a New Tetrakis(hydrosulfido) Diiridium Complex and Its Conversion into Homo- and Heterometallic Sulfido−Hydrosulfido Clusters
No full text
Preparation of a Heterobimetallic Cluster with Bridging Sulfido and Thiolato Ligands [{(η 5
No full textSynthesis and Protonation of N‑Heterocyclic-Carbene-Supported Dinitrogen Complexes of Molybdenum(0)
No full textThe
N-heterocyclic-carbene-supported dinitrogen (N<sub>2</sub>)
complexes of molybdenum(0) <i>trans</i>-MoÂ(N<sub>2</sub>)<sub>2</sub>(L<sup>R</sup>)<sub>4</sub> (L<sup>R</sup> = 1,3-R<sub>2</sub>-4,5-dimethylÂimidazol-2-ylidene; <b>2a</b>: R
= Me, <b>2b</b>: R = Et) and <i>mer</i>-MoÂ(N<sub>2</sub>)<sub>3</sub>(L<sup>R</sup>)<sub>3</sub> (<b>3</b>: R = <sup>i</sup>Pr) were synthesized from MoCl<sub>4</sub>(THF)<sub>2</sub> and KC<sub>8</sub> in the presence of L<sup>R</sup> under an atmosphere
of N<sub>2</sub>. In agreement with the characteristically strong
σ-donation from the N-heterocyclic carbenes to molybdenum, complexes <b>2a</b>, <b>2b</b>, and <b>3</b> exhibited lower N–N
stretching frequencies in their IR spectra and displayed longer N–N
as well as shorter Mo–N bond lengths in their molecular structures
relative to corresponding phosphine analogues. Although protonation
of the molybdenum-bound N<sub>2</sub> ligands in these phosphine complexes
with H<sub>2</sub>O is unprecedented, it was accomplished for <b>2a</b>, <b>2b</b>, and <b>3</b> under concomitant
release of ammonia
Synthesis and Protonation of N‑Heterocyclic-Carbene-Supported Dinitrogen Complexes of Molybdenum(0)
No full textThe
N-heterocyclic-carbene-supported dinitrogen (N<sub>2</sub>)
complexes of molybdenum(0) <i>trans</i>-MoÂ(N<sub>2</sub>)<sub>2</sub>(L<sup>R</sup>)<sub>4</sub> (L<sup>R</sup> = 1,3-R<sub>2</sub>-4,5-dimethylÂimidazol-2-ylidene; <b>2a</b>: R
= Me, <b>2b</b>: R = Et) and <i>mer</i>-MoÂ(N<sub>2</sub>)<sub>3</sub>(L<sup>R</sup>)<sub>3</sub> (<b>3</b>: R = <sup>i</sup>Pr) were synthesized from MoCl<sub>4</sub>(THF)<sub>2</sub> and KC<sub>8</sub> in the presence of L<sup>R</sup> under an atmosphere
of N<sub>2</sub>. In agreement with the characteristically strong
σ-donation from the N-heterocyclic carbenes to molybdenum, complexes <b>2a</b>, <b>2b</b>, and <b>3</b> exhibited lower N–N
stretching frequencies in their IR spectra and displayed longer N–N
as well as shorter Mo–N bond lengths in their molecular structures
relative to corresponding phosphine analogues. Although protonation
of the molybdenum-bound N<sub>2</sub> ligands in these phosphine complexes
with H<sub>2</sub>O is unprecedented, it was accomplished for <b>2a</b>, <b>2b</b>, and <b>3</b> under concomitant
release of ammonia
Tungsten(II) Alkylimido Complexes from Insertion of Nitriles into Tungsten Hydride: Alkylideneamido Intermediate Stage and Nitrene Group Transfer to Isocyanide
No full textThe tetrahydrido complex [WH<sub>4</sub>(κ<sup>4</sup>-<b>P4</b>)] (<b>P4</b> = <i>meso</i>-<i>o</i>-C<sub>6</sub>H<sub>4</sub>(PPhCH<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>)<sub>2</sub>) reacted with aliphatic nitriles
AkCN at 80 °C in toluene to afford a series of the imido complexes,
[WÂ(NCH<sub>2</sub>Ak)Â(κ<sup>4</sup>-<b>P4</b>)] (<b>2</b>). Similar reactions with aromatic nitriles ArCN proceeded
stepwise, leading to formation of the hydrido–alkylideneamido
complexes [WHÂ(Nî—»CHAr)Â(κ<sup>4</sup>-<b>P4</b>)]
(<b>3</b>) at the first stage and a subsequent isomerization
into the imido complexes [WÂ(NCH<sub>2</sub>Ar)Â(κ<sup>4</sup>-<b>P4</b>)] (<b>4</b>). Conversion of <b>3</b> into <b>4</b> was accelerated by electron-rich Ar groups such
as <i>p</i>-CH<sub>3</sub>OC<sub>6</sub>H<sub>4</sub>, while
it was completely inhibited when Ar was the considerably electron-deficient <i>p</i>-CF<sub>3</sub>C<sub>6</sub>H<sub>4</sub>. An X-ray crystallographic
study on <b>2</b> (Ak = <i>p</i>-ClC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>) and <b>4</b> (Ar = <i>p</i>-tolyl) has disclosed a distorted-square-pyramidal coordination geometry,
in which the apical position is occupied by the imido ligand with
a W<sup>II</sup>–N triple bond. An almost linear W<sup>II</sup>NC linkage of <b>3</b> (Ar = <i>p</i>-tolyl) has also been determined. Complex <b>2</b> was capable
of nitrene group transfer to isocyanide to produce carbodiimide
Tungsten(II) Alkylimido Complexes from Insertion of Nitriles into Tungsten Hydride: Alkylideneamido Intermediate Stage and Nitrene Group Transfer to Isocyanide
No full textThe tetrahydrido complex [WH<sub>4</sub>(κ<sup>4</sup>-<b>P4</b>)] (<b>P4</b> = <i>meso</i>-<i>o</i>-C<sub>6</sub>H<sub>4</sub>(PPhCH<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>)<sub>2</sub>) reacted with aliphatic nitriles
AkCN at 80 °C in toluene to afford a series of the imido complexes,
[WÂ(NCH<sub>2</sub>Ak)Â(κ<sup>4</sup>-<b>P4</b>)] (<b>2</b>). Similar reactions with aromatic nitriles ArCN proceeded
stepwise, leading to formation of the hydrido–alkylideneamido
complexes [WHÂ(Nî—»CHAr)Â(κ<sup>4</sup>-<b>P4</b>)]
(<b>3</b>) at the first stage and a subsequent isomerization
into the imido complexes [WÂ(NCH<sub>2</sub>Ar)Â(κ<sup>4</sup>-<b>P4</b>)] (<b>4</b>). Conversion of <b>3</b> into <b>4</b> was accelerated by electron-rich Ar groups such
as <i>p</i>-CH<sub>3</sub>OC<sub>6</sub>H<sub>4</sub>, while
it was completely inhibited when Ar was the considerably electron-deficient <i>p</i>-CF<sub>3</sub>C<sub>6</sub>H<sub>4</sub>. An X-ray crystallographic
study on <b>2</b> (Ak = <i>p</i>-ClC<sub>6</sub>H<sub>4</sub>CH<sub>2</sub>) and <b>4</b> (Ar = <i>p</i>-tolyl) has disclosed a distorted-square-pyramidal coordination geometry,
in which the apical position is occupied by the imido ligand with
a W<sup>II</sup>–N triple bond. An almost linear W<sup>II</sup>NC linkage of <b>3</b> (Ar = <i>p</i>-tolyl) has also been determined. Complex <b>2</b> was capable
of nitrene group transfer to isocyanide to produce carbodiimide
Synthesis and Structures of Tungsten (1-Pyridinio)imido Complexes and Their Facile N−N Bond Cleavage 1
No full textA Series of Dinuclear Homo- and Heterometallic Complexes with Two or Three Bridging Sulfido Ligands Derived from the Tungsten Tris(sulfido) Complex [Et 4
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