Complexes of Co(II), Cu(II), and Zn(II) with deprotonated methazolamide and ammonia are synthesized and characterized. The complex Zn(macm) 2 (NH 3 ) 2 crystallizes in the monoclinicC2c space group with a = 13.468(1), b = 6.759(1), c = 23.014(2) a, β = 90.27(1), and Z = 4. The structure was refined to R = 0.049 (R w = 0.053). The Zn(II) ion is coordinated to two deprotonated sulfonamido nitrogen atoms of the macm - ligand and two nitrogen atoms of the ammonia ligands in a distorted tetrahedron. The Zn(macm) 2 (NH 3 ) 2 complex is shown to be a simple model for the methazolamide inhibition of CA. EHMO calculations applied to fractional coordinates to the Zn(macm) 2 (NH 3 ) 2 complex indicate that the atomic orbitals of the Zn do not contribute to HOMO and LUMO of the complex. The characteristics of the Cu(macm) 2 (NH 3 ) 3 (H 2 O) as an anticonvulsant agent are tested.