A copper(II)–oxalate compound resulting from the fixation of carbon dioxide: μ-oxalato-bis[bis(1-benzyl-1H-pyrazole)(trifluoromethanesulfonato)copper(II)]

Abstract

Reductive coupling of adventitious CO2 by CuI has afforded the title compound, μ‐oxalato‐1κ2O1,O2:2κ2O1′,O2′‐bis­[bis­(1‐benzyl‐1H‐pyrazole‐κN2)(trifluoro­methane­sulfonato‐κO)copper(II)], [Cu2(CF3O3S)2(C2O4)(C10H10N2)4], which contains centrosymmetric mol­ecules in which the CuII ions, bridged by a planar oxalate ligand, exhibit a distorted square‐pyramidal N2(pyrazole)O2(oxalato)O(trifluoro­methane­sulf­on­ate) coordination geometry, with the trifluoro­methane­sulfonate ligand coordinated axially. The mol­ecule exhibits five intra­molecular C—H⋯O,F hydrogen bonds per asymmetric unit, which help to stabilize the mol­ecule and to orient the benzyl and trifluoro­methane­sulfonate groups. Inter­molecular C—H⋯O hydrogen bonds link the mol­ecules to form two‐dimensional layers.

RETRACTED ARTICLE: Reduction of carbon dioxide to oxalate by a binuclear copper complex

“…4) contains dimeric cationic complexes with crystallographically imposed 2/m (C 2h ) symmetry. The Cu Á Á Á Cu separation (5.4213(7) Å), and the distances within the bridging oxalate ligand (C-C 1.544(7) Å; C-O 1.248(3) Å), are similar to those observed in other C 2 O 4 2 À -bridged copper complexes 12,13,20 . We tested the selectivity of the reaction of complex 3 with CO 2 , by generating the Cu(I) dimer as described above and allowing the solution to evaporate in air in a petri dish or watch glass.…”

“…The yields of empty complexes after HX treatment were nearly quantitative: 94% (HCl) and 96%(HNO 3 ). The oxalic acid produced in these reactions was characterized by 13 C nuclear magnetic resonance ( 13 C NMR; 163.2 ppm) and FTIR (n CO ¼ 1668 cm À 1 ; with 13 CO 2 , 1642 cm À 1 ) spectroscopy.…”

“…The reaction mixture showed no changes in its ultraviolet-visible spectrum for 48 h. At that point, the N 2 was replaced by 13 CO 2 . The yellow solution progressively turned to green over a period of 128 h; during this period, 13 CO 2 was added periodically to maintain the pressure at B1 atm. After the reaction was complete, the solution was poured into a watch glass and left for crystallization by slow evaporation of DMF.…”

“…There have been several reports of reduction of CO 2 to oxalate by low-valent d-block [11][12][13][14][15] and f-block metal complexes [16][17][18] . The Limberg group recently used b-diketiminate-based nickel(I) complexes to reduce CO 2 to CO or C 2 O 4 2 À in multi-step processes 19 .…”

A second monoclinic polymorph of {bis[5-methyl-3-(trifluoromethyl)pyrazol-1-yl]borato}{tris[5-methyl-3-(trifluoromethyl)pyrazol-1-yl]borato}cobalt(II): a structure containing a B—H...Co agostic interaction

“…With pyrazole, a variety of metal complexes has been prepared, predominantly with copper , including the Cu(II) complex of an unusual (dimethylamino)methane bridged bis(pyrazole) ligand formed via a DMF aminalization (Stibrany et al, 1999) and a novel binuclear µ-oxalato(1-benzylpyrazole) 2 (CF 3 SO 3 ) 2 copper(II) compound resulting from the fixation of carbon dioxide (Stibrany et al, 2005). A tris(pyrazolyl)arene ligand which forms geometrically constrained metal complexes has also been prepared , as has a sterically strained trigonal-bipyramidal Cu(II) complex containing a 1-benzylpyrazole ligand (Stibrany & Potenza, 2009b).…”