METAL-COMPLEXES OF 5-TERTBUTYLOXYCARBONYLAMIDO-1,3,4-THIADIAZOLE-2-SULFONAMIDE (B-H(2)ATS), A CARBONIC-ANHYDRASE INHIBITOR - SYNTHESIS AND CHARACTERIZATION OF THE COPPER(II) COMPLEX - CRYSTAL-STRUCTURES OF B-H(2)ATS AND THE [CU(B-ATS)(NH3)(2)](2) DIMER COMPLEX

A new acetazolamide derivative, 5-tertbutyloxycarbonylamido-1,3,4-thiadiazole-2-sulfonamide (B-H(2)ats), has been prepared and examined as a chelating agent towards copper(II) ion. The crystal structures of the ligand and the [Cu(B-ats)(NH3)(2)](2) complex were determined by single-crystal X-ray diffraction. Crystal data for B-H(2)ats: a = 11.246(3), b = 9.10(1), c = 12.486(5) Angstrom, beta = 100.94(6)degrees, Z = 4 and V = 1255(2) Angstrom(3). The refinement of the structure based on 1454 reflections yielded R = 0.041 and wR = 0.046. Crystal data of the copper(II) complex: a = 7.084(7), b = 7.970(4), c = 13.76(1) Angstrom, alpha = 105.70(5), beta = 97.99(5)degrees, gamma = 99.08(7)degrees, Z = 1 and V = 725(1) Angstrom(3). The refinement of the structure based on 850 reflections yielded R = 0.064 and wR = 0.061. The two copper(II) ions, linked by two thiadiazole N-N groups from two adjacent B-ats ligands form a nearly planar six-membered ring with a copper-copper distance of 4.27(2) Angstrom. The coordination polyhedron around the copper is intermediate between a square pyramid and a trigonal bipyramid. The magnetic susceptibilities measured from 4.7 K show a weak antiferromagnetic spin coupling. The IR, reflectance diffuse and EPR spectra and the thermal properties were studied.