SYNTHESIS AND CHARACTERIZATION OF COPPER(II) ACETAZOLAMIDE (5-ACETAMIDO-1,3,4-THIADIAZOLE-2-SULFONAMIDE) COMPLEXES - CRYSTAL-STRUCTURE OF DIMERIC [CU(ACM)(NH3)2(OH2)]2.2H2O

The synthesis and characterization of four copper(II) complexes with the deprotonated acetazolamide ligand (Acm) are described. The crystal and molecular structures and IR spectra of [Cu(Acm)(NH3)2(OH2)]2−2H2O (I) are reported and compared with the crystal and molecular structures and IR spectra of Ni(Acm)2(NH3)4, described in a previous paper. The copper(II) compound crystallizes in the triclinic space group P1, Z = 1, with the cell dimensions a = 7.548 (4) Å, b = 8.205 (17) Å, c = 10.797 (3) Å, a = 93.59 (6)°, ² = 108.68 (3)°, and γ = 98.50 (9)°. The structure was solved by direct methods and refined by least-squares calculations to a conventional R factor of 7.0% for 1867 counter data. The structure consists of discrete dimeric [Cu(Acm)-(NH3)2(OH2)]2units and uncoordinated water molecules. The metal ions in the dinuclear entity are linked through two N-N groups from the thiadiazole rings, which belong to two adjacent Acm ligands, forming with the bridging atoms a six-membered ring. Each copper(ll) ion shows a tetragonally elongated octahedral geometry. The electronic, IR, and EPR data are consistent with the crystal structure. The study of reciprocal molar susceptibility vs temperature indicates that there is no appreciable interaction between copper ions. Magnetic and EPR data of the other compounds synthesized suggest a different environment for the copper(ll) ions. © 1990, American Chemical Society. All rights reserved.