P-KAPPA-A OF ZINC-BOUND WATER AND NUCLEOPHILICITY OF HYDROXO-CONTAINING SPECIES - ABINITIO CALCULATIONS ON MODELS FOR ZINC ENZYMES

Ab initio Hartree-Fock calculations have been performed on a series of zinc complexes containing a coordinated water molecule in order to understand the factors governing the pATaof the coordinated water and the nucleophilicity of the Zn-OH and Zn-OH2groups. The systems investigated include Zn(NH3)nOH22+(n = 3-5), Zn(NH3)2(OCOH)OH2+, Zn(NH3)2(SCH3)OH2+, Zn-(NH3)(SCH3)2OH2, and their deprotonated partners. The order of nucleophilicity for the various compounds is presented, as well as the order of acidity of the aqua complexes. The latter order is compared with the values found in metalloproteins. © 1990, American Chemical Society. All rights reserved.