Copper complexes modelling the interaction between benzolamide and Cu-substituted carbonic anhydrase. Crystal structure of Cu(bz)(NH3)4 complex

Abstract New copper benzolamide (H 2 bz, 5-phenylsulfonamide-1,3,4-thiadiazole-2-sulfonamide) complexes with ammonia, diethylentriamine (dien) and dipropylentriamine (dipn) have been prepared. The complex [Cu(bz)(NH 3 ) 4 ] crystallises in the monoclinic space group P 2 1 / n with a = 7.621(3), b = 19.91(5), c = 11.291(3) A, β = 93.17(4)° and Z = 4. The Cu(II) is five-coordinated with an almost regular square pyramidal geometry. The dideprotonated sulfonamide behaves as monodentate ligand interacting with the metal ion through the N atom of the unsubstituted sulfonamide group. In the EPR spectrum, exchange coupling between Cu(II) polyhedra of different orientations in the unit cell is observed. The dien and dipn ligands provide a model of the histidine environment of the metal ion in carbonic anhydrase (CA). From the spectroscopic properties, the ternary triamine complexes can be considered as analogous of the adducts formed by Cu-CA and the inhibitor benzolamide.