The Chemical Modeling of Carbonic Anhydrase ——Synthesis and Characterization of Tris(pyrazoly)hydroborato Metal Complexes η3-HB(3-Ar5-Mepz)3 MX (M=Ni, Cu, Zn, Cd; Ar=2'-thie, Ph; X=Cl, NO3)
GUO Sheng-Li, LIU Sheng-Ming, YIN Yuan-Qi, YU Kai-Bei
1998, 19(5):
741-747.
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A series of tris(pyrazolyl)hydroborato metal complexes, η3-HB(3-Ar-5-Mepz)3 MX(M=Ni, Cu, Zn, Cd; Ar=2'-thie, Ph; X=Cl, NO3) had been synthesized and characterized. The determination of X-ray crystal structure shows, the complex{η3-HB(3-(2'- thie)-5-Mepz)3 }Zn(NO3)·1/2THF(2c) exhibits anisobidentate coordination of the nitrate ligand Zn—O(2) 0.196 6(4) nm, Zn—O(3) 0.246 3(4) nm, in contrast to the bidentate coordination fashion that is observed in the cadmium analogue{ η3-HB(3-Ph-5-Mepz)3 Cd(NO3)(THF)}(2e) 0.233 4(3) and 0.2356(3) nm . Cadmium substituted carbonic anhydrase(CA) is less active than zinc enzyme, among many other factors, such as the p Ka of the coordinated water, that facile access to a unidentate bicarbonate intermediate may be an important requirement for CAactivity. Both of 2c and 2e are triclinic with space group P1, Z=2. For 2c, a=1.16250(10) nm, b=1.2422(2) nm, c=1.32590(10) nm; α=71.410(10)°, β=73.090(10)°, γ=65.660(10)°; final R=0.0755. While for 2e they are: a=1.13030(10) nm, b=1.2099(2) nm, c=1.2607(2) nm; α=102.050(10)°, β=91.780(10)°, γ=93.620(10)°; final R=0.0302.
