6533b833fe1ef96bd129ca9a

RESEARCH PRODUCT

Coordinative versatility of the carbonic anhydrase inhibitor benzolamide in zinc and copper model compounds

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New benzolamide (H 2 bz, 5-phenylsulfonamide-1,3,4-thiadiazole-2-sulfonamide) zinc(II) and copper(II) complexes with tris(2-benzimidazolyl-methylamine) (L) and ammonia are reported. The crystal structures of the Zn(II) complexes were determined. The [Zn(Hbz)L]ClO 4 · H 2 O compound crystallizes in the triclinic space group with a =11.006(1), b =14.777(2), c =14.918(2) A, α =114.30(1), β =98.90(1), γ =107.36(1)° and Z =2. In this compound the Zn(II) has a distorted trigonal bipyramidal geometry. The {[Zn 2 (bz) 2 (NH 3 ) 4 ] · 2H 2 O} ∞ crystallizes in the monoclinic space group C 2/ c with a =23.530(3), b =10.4124(11), c =15.428(2) A, β =110.591(9)° and Z =4. The metal centre is in a distorted tetrahedral [ZnN 4 ] environment. The benzolamide presents a different coordination behaviour in these complexes. In [Zn(Hbz)L]ClO 4 · H 2 O it acts as a monodentate ligand through the thiadiazole N atom contiguous to the deprotonated sulfonamido group, while in {[Zn 2 (bz) 2 (NH 3 ) 4 ] · 2H 2 O} ∞ it behaves as a bridge joining two Zn(II) ions via the N atom of the thiadiazole ring and the N atom of the free sulfonamido group. The Cu(Hbz)L(NO 3 ) complex was also obtained and characterized. The electronic properties and the EPR of the copper-doped zinc complexes showed that the copper(II) ion adopts a square pyramidal geometry. Also, for the Zn(II) complexes the interaction Zn–benzolamide has been studied using extended-Huckel molecular-orbital (EHMO) calculations.