Synthesis and structures of tris(pyrazolyl)hydroborato metal complexes as structural model compounds of carbonicanhydrase

A series of tris(pyrazoly)hydroborato metal complexes [eta(3)-HB(3-R-1-5-R( 2)pz)(3)]MX (R-1=Ph, 2'-thienyl, R-2=CH3, Ph; M=Ni, Cu, Zn, Cd; X=Cl-, NO3- CH3COO-) and [eta(3)-HB(3-Ph-5-Mep;)(3)](3-Me5-Phpz)Cu(PhCOO), 8, had been synthesized and characterized. Among them, the complexes [eta(3)-HB(3,5-Ph (2)pz)(3)]NiCl (3), [eta(3)-HB(3-Ph-5-Mepz)(3)]Cd(NO3)(THF) (4) and 8 were analyzed by X-ray crystal structure determination, which revealed the biden tate coordination of NO3- in complex 4 and isomerized ligands in complex 8. As model compounds of carbonic anhydrase (CA), the structures of these com plexes were contrasted to that of the active site of CA: the derivative chl oro may be the closest model compounds among them. The relationship between the coordination modes of X (X = NO3- CH3COO-; PhCOO-) in complexes and th eir IR spectra was also discussed. (C) 1998 Elsevier Science Ltd. All right s reserved.