Copper Complexes of Nitrogen-Anchored Tripodal N-Heterocyclic Carbene Ligands

Incorporation of a nitrogen functionality into a tripodal N-heterocyclic carbene ligand system affords the first N-anchored tetradentate tris-carbene ligands TIMENR I (R = Me (5a), t-Bu (5b), Bz (5c)). Treatment of the Me derivatized [H3TIMENMe](PF6)3 imidazolium salt (H35a) with silver oxide yields the silver complex [(TIMENMe)2Ag3](PF6)3 (9), which, in a ligand transfer reaction, reacts with copper(I) bromide to give the trinuclear copper(I) complex [(TIMENMe)2Cu3](PF6)3 (10). Deprotonation of the tert-Bu and benzyl derivs. [H3TIMENt-Bu](PF6)3 and [H3TIMENBz](PF6)3 yields the free tris-carbenes TIMENt-Bu (5b) and TIMENBz (5c), which react readily with copper(I) salts to give mononuclear complexes [(TIMENt-Bu)Cu](PF6) (11b) and [(TIMENBz)Cu]Br (11c). The solid-state structures of 10, 11b, and 11c were detd. by single-crystal x-ray diffraction. While the TIMENMe ligand yields trinuclear complex 10, with both T-shaped three-coordinate and linear two-coordinate copper(I) centers, the TIMENt-Bu and TIMENBz ligands induce mononuclear complexes 11b and 11c, rendering the cuprous ion in a trigonal planar ligand environment of three carbenoid carbon centers and an addnl., weak axial nitrogen interaction. Complexes 11b and 11c exhibit reversible one-electron redox events at half-wave potentials of 110 and -100 mV vs Fc/Fc+, resp., indicating sufficient electronic and structural flexibility of both TIMENR ligands (R = t-Bu, Bz) to stabilize copper(I) and copper(II) oxidn. states. Accordingly, a copper(II) NHC complex, [(TIMENBz)Cu](OTf)2 (12), was synthesized. Paramagnetic complex 12 was characterized by elemental anal., EPR spectroscopy, and SQUID magnetization measurements. [on SciFinder (R)]


Published in:
Journal of the American Chemical Society, 125, 40, 12237-12245
Year:
2003
Keywords:
Note:
CAN 139:350812 29-9 Organometallic and Organometalloidal Compounds Department of Chemistry and Biochemistry,University of California San Diego,La Jolla,CA,USA. Journal 0002-7863 written in English. 618120-44-8P; 618120-52-8P Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), PRP (Properties), RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), PROC (Process), RACT (Reactant or reagent) (crystal structure and electrochem. redox; prepn., crystal structure, and electrochem. behavior of copper complexes of nitrogen-anchored tripodal N-heterocyclic carbene ligands); 618120-53-9P Role: PRP (Properties), SPN (Synthetic preparation), PREP (Preparation) (crystal structure; prepn., crystal structure, and electrochem. behavior of copper complexes of nitrogen-anchored tripodal N-heterocyclic carbene ligands); 618120-42-6P Role: PRP (Properties), SPN (Synthetic preparation), PREP (Preparation) (mol. structure; prepn., crystal structure, and electrochem. behavior of copper complexes of nitrogen-anchored tripodal N-heterocyclic carbene ligands); 618120-55-1P Role: PRP (Properties), SPN (Synthetic preparation), PREP (Preparation) (prepn., crystal structure, and electrochem. behavior of copper complexes of nitrogen-anchored tripodal N-heterocyclic carbene ligands); 555-77-1 (Tris(2-chloroethyl)amine); 616-47-7 (N-Methylimidazole); 4238-71-5 (N-Benzylimidazole); 45676-04-8 (N-tert-Butylimidazole); 64443-05-6 (Tetrakis(acetonitrile)copper(I) hexafluorophosphate) Role: RCT (Reactant), RACT (Reactant or reagent) (prepn., crystal structure, and electrochem. behavior of copper complexes of nitrogen-anchored tripodal N-heterocyclic carbene ligands); 618120-36-8P; 618120-37-9P; 618120-38-0P; 618120-40-4P; 618120-45-9P; 618120-47-1P; 618120-49-3P; 618120-50-6P; 618120-51-7P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (prepn., crystal structure, and electrochem. behavior of copper complexes of nitrogen-anchored tripodal N-heterocyclic carbene ligands)
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