A CO(III) COMPLEX OF CARBONIC-ANHYDRASE INHIBITOR METHAZOLAMIDE AND THE AMINO-IMINO AIB LIGAND FORMED BY REACTION OF ACETONE AND AMMONIA

Reaction of Co(NO3)2-6H2O with methazolamide {[N-(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2(3H)-ylidene)acetamide] (Hmacm)} and ammonia in acetone to produce [Co(methazolamidate)(2-methyl-2-amino-4-iminopentane)2(NH3)](NO3)2.2H2O is described. The ligand 2-methyl-2-amino-4-iminopentane (aib) is the product obtained from the condensation of two ammonia and two acetone molecules. The complex crystallizes in the monoclinic space group P2(1)/c with a = 16.713(5), b = 9.180(1), c = 20.273(1) angstrom, beta = 97.44(4)degrees for Z = 4. The R value is 0.081 for 2150 significant reflections. The Co(III) ion exhibits a nearly regular octahedral arrangement with the Co-N bond distances in the range 1.91-1.98 angstrom. The Co(III) ion is obtained by spontaneous oxidation of Co(II). Methazolamide interacts as a monodentate ligand through the deprotonated sulfonamido N atom in a similar way to the bonding of the inhibitor in the carbonic anhydrase enzyme.