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

The new ligand hydrotris(3-(2′-furyl)-5-methylpyrazolyl)borate (TpFu,Me) was prepared by the usual procedure. With zinc salts, it forms the TpFu,MeZn–X complexes (X = Cl, Br, I, NCS, CH3COO, CF3COO). With zinc perchlorate, the bis-ligand complex Zn(TpFu,Me)2 is formed preferrably, but by carefully controlling the reaction conditions, the “enzyme model” TpFu,MeZn–OH could be obtained. The latter models carbonic anhydrase by inserting CO2 and CS2 in methanol producing TpFu,MeZn–OCOOMe and TpFu,MeZn–SCSOMe. It models hydrolases by the hydrolytic cleavage of tris(p-nitrophenyl)phosphate and γ-thiobutyrolactone. It does not hydrolyse trifluoroacetamide, but instead deprotonates it, yielding TpFu,MeZn–NHCOCF3.