om010139y_si_001.cif (31.1 kB)

Nickel(II) cis- and trans-Dimethyl Complexes of Di-N-heterocyclic Carbenes

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posted on 10.05.2001, 00:00 by Richard E. Douthwaite, Malcolm L. H. Green, Peter J. Silcock, Pedro T. Gomes
Alkyl complexes of Ni(II) incorporating di-N-heterocyclic carbenes, tBuCCmeth and tBuCCeth (where tBuCCmeth = 1,1‘-methylene-3,3‘-di-tert-butyl-diimidazole-2,2‘-diylidene and tBuCCeth = 1,2-ethylene-3,3‘-di-tert-butyl-diimidazole-2,2‘-diylidene), have been prepared for the first time. The complexes [{trans-NiMe2(PMe3)}2(μ-tBuCCmeth)] (1) and [Ni(tBuCCeth)Me2] (2) have been prepared and characterized by single-crystal X-ray diffraction, and the complex [Ni(tBuCCmeth)Me2] (3) has been observed spectroscopically. Thermal decomposition studies show that 2 eliminates methane rapidly and quantitatively above 50 °C by a predominantly unimolecular dissociative pathway with activation parameters ΔH = 24.0(6) kcal mol-1 and ΔS = −4.7(1) cal K-1 mol-1.