A new tris(2-furyl) substituted pyrazolylborate ligand and its zinc complex chemistry

The new ligand hydrotris(3-(2'-furyt)-5-methylpyrazolyl)borate (Tp(Fu,Me)) was prepared by the usual procedure. With zinc salts, it forms the Tp(FuMe)Zn-X complexes (X = Cl, Br, I, NCS, CH3COO, CF3COO). With zinc perchlorate, the bis-ligand complex Zn(Tp(Fu,Me))(2) is formed preferrably, but by carefully controlling the reaction conditions, the "enzyme model" Tp(Fu,Me)Zn-OH could be obtained. The latter models carbonic anhydrase by inserting CO2 and CS2 in methanol producing Tp(Fu,Me)Zn-OCOOMe and Tp(Fu,Me)Zn-SCSOMe. It models hydrolases by the hydrolytic cleavage of tris(p-nitrophenyl)phosphate and gamma-thiobutyrolactone. It does not hydrolyse trifluoroacetamide, but instead deprotonates it, yielding Tp(Fu,Me)Zn-NHCOCF3. (c) 2006 Elsevier B.V. All rights reserved.