Carboxy and Phosphate Esters Cleavage with Mono- and Dinuclear Zinc(II) Macrocyclic Complexes in Aqueous Solution. Crystal Structure of [Zn2L1(μ-PP)2(MeOH)2](ClO4)2 (L1 = [30]aneN6O4, PP- = Diphenyl Phosphate)
- 1 June 1997
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 36 (13) , 2784-2790
- https://doi.org/10.1021/ic961521j
Abstract
The ligand [30]aneN(6)O(4) (L1) binds two Zn(II) in aqueous solution. The stability constants of the L1 complexes have been determined at 308.1 K by means of potentiometric measurements. Dinuclear monohydroxo [Zn(2)L1OH](3+) and dihydroxo [Zn(2)L1(OH)(2)](2+) complexes are formed in aqueous solution from neutral to alkaline pH. The kinetics of promoted hydrolysis of p-nitrophenyl acetate (NA) was studied. Both hydroxo species promote p-nitrophenyl acetate (NA) hydrolysis at 298.1 K with second-order kinetics. The activity of these species in NA hydrolysis is similar to that found for the mononuclear L2-Zn-OH(+) complex (L2 = [15]aneN(3)O(2)), indicating that the hydrolytic process takes place via a simple bimolecular mechanism. The hydrolysis rate of bis(p-nitrophenyl) phosphate (BNP) was measured in aqueous solution at 308.1 K in the presence of the L1and L2 zinc complexes. The hydrolysis rate of BNP is increased almost 10-fold by the dinuclear [Zn(2)L1(OH)(2)](2+) complex with respect to the mononuclear L2-Zn-OH(+) one. This result indicates a cooperative role of the two metals in the hydrolytic mechanism. A bridging coordination of the phosphate ester to the two Zn(II) ions can be suggested. The crystal structure of [Zn(2)L1(&mgr;-PP)(2)(MeOH)(2)](ClO(4))(2) (PP(-) = diphenyl phosphate) (space group P&onemacr;, a = 10.681(5) Å, b = 12.042(1) Å, c = 13.191(3) Å, alpha = 74.63(2) degrees, beta = 71.74(3) degrees, gamma = 68.41(2) degrees, V = 1476.4(8) Å(3), Z = 1, R = 0.0472, R(w)(2) = 0.1166) strongly supports this hypothesis, since in the [Zn(2)L1(&mgr;-PP)(2)(MeOH)(2)](2+) cation the diphosphate anions bridge the two metals. The dinuclear Zn(II) complexes of L1 provide a simple model system for hydrolytic dizinc enzymes.Keywords
This publication has 24 references indexed in Scilit:
- CO2 Fixation by Novel Copper(II) and Zinc(II) Macrocyclic Complexes. A Solution and Solid State StudyInorganic Chemistry, 1996
- Hydrolysis of a Phosphate Diester Doubly Coordinated to a Dinuclear Cobalt(III) Complex: A Novel MechanismAngewandte Chemie International Edition in English, 1995
- La(III)-Hydrogen Peroxide Cooperativity in Phosphate Diester Cleavage: A Mechanistic StudyJournal of the American Chemical Society, 1995
- The catalytic carboxyester hydrolysis by a new zinc(II) complex with an alcohol-pendant cyclen (1-(2-hydroxyethyl)-1,4,7,10-tetraazacyclododecane): A novel model for indirect activation of the serine nucleophile by zinc(II) in zinc enzymesJournal of the American Chemical Society, 1995
- Carboxylate-Bridged Heterodimetallic ComplexesJournal of the American Chemical Society, 1994
- Reactivity of a chelated phosphate esterInorganic Chemistry, 1994
- The first anionic sulfonamide-binding zinc(II) complexes with a macrocyclic triamine: chemical verification of the sulfonamide inhibition of carbonic anhydraseJournal of the American Chemical Society, 1992
- Zinc Pyrazolylborate Complexes Relevant to the Biological Function of Carbonic AnhydraseAngewandte Chemie International Edition in English, 1992
- Coordination tendencies of a series of tetraazacycloalkanes related to 1,4,7,10-tetraazadecane (trien): synthetic, thermodynamics, and structural aspectsInorganic Chemistry, 1984
- Crystal and molecular structure of the ternary complex bis[(adenosine 5'-triphosphato)(2,2'-bipyridine)zinc(II)] tetrahydrateJournal of the American Chemical Society, 1981