425370-02-1Relevant articles and documents
Cu(I) complexes of pincer pyridine-based N-heterocyclic carbenes with small wingtip substituents: Synthesis and structural and spectroscopic studies
Domyati, Doaa,Hope, Sydney L.,Latifi, Reza,Hearns, Micah D.,Tahsini, Laleh
, p. 11685 - 11693 (2016/12/03)
Six new Cu(I) complexes with pincer N-heterocyclic carbene (NHC) ligands of the type 2,6-bis(3-alkylimidazol-2-ylidene)pyridine, I(R)CNC, and 2,6-bis(3-alkylimidazol-2-ylidene)methylpyridine, I(R)C^N^C, where R = Me, Et, and iPr have been synthesized using Cu precursors and bis(imidazolium) salts. All of these compounds, namely, [Cu2(IMeCNC)2](PF6)2, 1; [Cu2(IEtCNC)2](PF6)2, 2; [Cu2(IiPrCNC)2](PF6)2, 3; [Cu(IMeC^N^C)](PF6), 4; [Cu(IEtC^N^C)](PF6), 5; and [Cu(IiPrC^N^C)](PF6), 6, have been characterized by 1H and 13C NMR spectroscopies, elemental analysis, solution conductivity, and electrochemical studies. Single crystal X-ray structures were obtained for all complexes except 1. The crystallographic data reveal a binuclear structure containing two Cu atoms at a close distance, 2.622-2.811 ? for all the complexes except 5, which shows a unique mononuclear structure. Spatial syn arrangement of ethyl groups and extensive π-π stacking in the solid state accounts for the mononuclear structure of complex 5. A pseudolinear coordination geometry about metal centers consisting of two Cu-carbene bonds, as well as weak Cu-pyridine interactions, exist among all the complexes independent of their ligand. Solution-state conductivity data reveal a dominant 1:2 electrolyte behavior for 1-3 but 1:1 electrolyte for 4-6, consistent with the sustainable binuclear structure in solutions of Cu(I)-I(R)CNC complexes. Cyclic voltammetry and differential pulse voltammetry studies reveal an irreversible and two quasi-reversible peaks for the one-electron oxidation of solvent-bound and solvent-free binuclear and mononuclear Cu-NHC species in complexes 1-3. In contrast, the reversible Cu(II)/Cu(I) couples of 4-6 at potentials close to that of complexes with tripodal polydentate NHC scaffolds indicate the electronic and structural flexibility of I(R)C^N^C ligands to accommodate both Cu(I) and Cu(II) ions.
A bis-acetonitrile two-coordinate copper(I) complex: Synthesis and characterization of highly soluble B(C6F5)4- salts of [Cu(MeCn)2]+ and [Cu(MeCn)4]+
Liang, Hong-Chang,Kim, Eunsuk,Incarvito, Christopher D.,Rheingold, Arnold L.,Karlin, Kenneth D.
, p. 2209 - 2212 (2008/10/08)
Copper(I)-acetonitrile complexes are exceedingly useful starting materials for the synthesis of copper(I) complexes with polydentate ligands. To extend the utility of such chemistry to solution studies in relatively low-dielectric solvents (i.e., diethyl ether, toluene) and to aid in obtaining products amenable to X-ray diffraction studies, we have recently begun to employ counteranions such as B(C6F5)4- for bioinorganic studies. Thus, the synthesis of [Cu(MeCN)4]B-(C6F5)4 (1) is presented. Its recrystallization from CH2CI2/pentane yields the linear, two-coordinate complex [Cu(MeCN)2]B(C6F5)4 (2), whose centrosymmetric X-ray structure shows that its Cu-N distance is significantly shorter than that in other two-coordinate Cu(I) complexes with nitrogen ligands or that in the tetrahedral complex [Cu(MeCN)4]CIO4. Infrared spectroscopy indicates interesting and diagnostically useful differences between the v(CN) of 1 and 2.
