X-Ray crystal structures of some adducts of dimeric copper(II) acetate. Nature of the copper–copper interaction
Abstract
The crystal structures of the adducts of Cu2(OCOCH3)4 with methanol (1), acetic acid (2), dimethylformamide (3), and 1,4-diazabicyclo [2.2.2] octane (4) have been determined using single-crystal X-ray diffraction methods. The compounds are isostructural with that of Cu2(OCOCH3)4·2H2O with the water molecules in the axial positions being replaced by the respective ligands. The ligand 1,4-diazabicyclo[2.2.2]octane bridges two dimer units producing a chain structure, in which this ligand is disordered around the N–N axis. Crystal data : (1), monoclinic, space group P21/n, a= 8.129(2), b= 7.447(1), c= 13.332(1)Å, β= 92.21(1)°, and Z= 2; (2), space group, P21/n, a= 15.153(2), b= 7.772(1), c= 8.229(1)Å, β= 103.08(1)°, and Z= 2; (3), triclinic, space group P, a= 8.002(1), b= 8.140(1), c= 9.394(2)Å, α= 105.85(2), β= 92.31 (2), γ= 113.84(1)°, and Z= 1; (4), monoclinic, space group A2/m, a= 7.709(7), b= 15.490(8), c= 8.172(3)Å, β= 105.51(5)°, and Z= 2. The structures have been solved by the heavy-atom method and refined to R values of 0.041 (1), 0.029 (2), 0.032 (3), and 0.065 (4) using, respectively, 1 787, 1 892, 1 600, and 594 diffractometer-measured intensities. The X-ray crystallographic results together with literature data have been utilised to examine a general relationship between the donor ability of the axial ligands and the length of the Cu–C ubond and draw some conclusions regarding the nature of this bond.