Copper(I) oxalate complexes: Synthesis, structures and surprises

Abstract

A series of dinuclear copper(I) oxalate complexes was synthesized by the direct acid-base reaction of Cu2O with oxalic acid in ethanol with a ligand, or in neat ligand. The complexes incorporated a variety of ligands L (L = triphenylphosphine, 1,2bis(diphenylphosphino)ethane, triphenylphosphite, diisopropyl sulfide, cyclooctadiene and cyclohexylisocyanide) and had the general formula LnCu(µ2-C2O4)CuLn (n = 1 or 2). The Cu I /Cu II mixed-valence trinuclear compound (iPr2S)2Cu I (C2O4)Cu II (C2O4)Cu I (iPr2S)2 was formed concomitantly with the target dinuclear Cu2C2O4(iPr2S)4 complex, shedding light on the mechanism of disproportionation of this family of complexes. With norbornadiene (nbd) as a ligand, however, a coordination polymer Cu2C2O4(nbd) was formed. Also, the same reaction with L = 2,9-dimethyl-1,10-phenanthroline or pyridine resulted in the known tetrahedral complex ions [CuLm] + (m = 2 or 4). Lastly, the ligand di-2-(1-di-(2-picolyl)amino)propyl 3 disulfide produced not the expected Cu(I) oxalate complex, but a Cu(II) picolylamine oxalate coordination polymer. All products were structurally characterized by single-crystal X-ray diffraction if soluble, and by powder X-ray diffraction methods if not.

Solvometallurgical recovery of cobalt from lithium-ion battery cathode materials using deep-eutectic solvents

“…4,[53][54][55] These acids form poorly soluble copper(II) salts as well, which coprecipitate with the cobalt(II) salts, making separation of cobalt from copper difficult. 4,53,56,57 The choline chloride-citric acid DES (ChCl : CA) leached more cobalt(II) compared to the choline chloride-malic acid DES, due to the higher acidity of citric acid. 52,54,55 Moreover, citric acid is also cheaper and more readily available than malic acid.…”

“…As mentioned above, copper(I/II)and cobalt(II) oxalate precipitates are easily formed. 4,53,57 Therefore, oxalic acid was used to strip and precipitate copper from the loaded LIX 984 phase and cobalt from the loaded A336 phase. 102 Fig.…”

Towards Optimized Photoluminescent Copper(I) Phenanthroline-Functionalized Complexes: Control of the Photophysics by Symmetry-Breaking and Spin–Orbit Coupling

“…The Cu–N distances vary from 1.996 Å to 2.081 Å, the X 1 –Cu–X 2 angle from 144.8° to 180.0° and the C 1 –X 1 –X 2 –C 2 dihedral from 33.9° to 90° ( Table S1 ). The situation is similar for 1 Me [ 81 , 82 , 83 , 84 , 85 , 86 ] ( Table S2 ). In both cases, the computed GS structure is within the range of experimental data.…”

“…Distances are in Angstroms, angles and dihedral angles in degrees. References [ 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 ] are cited in the Supplementary Materials.…”

An Oxalate-Bridged Copper(II) Complex Combining Monodentate Benzoate, 2,2′-bipyridine and Aqua Ligands: Synthesis, Crystal Structure and Investigation of Magnetic Properties

“…Among these ligands, the oxalate ion, ox 2− , for example, is well known for its capability to create adequate magnetic exchange pathways for ferro-and antiferromagnetic interactions in oligonuclear copper(II) compounds [9][10][11]. The combination of oxalate and copper(II) ions leads to a large structural variety including different nuclearities such as mononuclear [12,13], dinuclear [14,15], trinuclear [16,17], tetranuclear [17,18] and hexanuclear species [19,20] and coordination polymers [14,21]. This class of oxalate-bridged compounds is noteworthy in magnetic applications, as it may comprise many other transition metal ions such as Mn II , Fe II/III , Co II , Ni II , Cr II/III , V IV and Ru II [22][23][24][25].…”