Fixation of CO₂ by Zinc(II) Chelates in Alcoholic Medium. X-ray Structures of {[Zn(cyclen)]₃(μ₃-CO₃)}(ClO₄)₄ and [Zn(cyclen)EtOH](ClO₄)₂

Abstract

The fixation of CO(2) on Zn(II) chelates in alcoholic medium was studied in efforts to synthesize alkyl carbonates. In the presence of a base, such as NEt(3), the tetraazacyclododecane complex of Zn(II) in alcoholic solution binds CO(2) and forms a &mgr;(3)-carbonate complex. This complex was characterized by NMR spectroscopy and X-ray analysis. Crystal data: orthorhombic; space group Pcba; a = b = c = 21.850(5) Å; alpha = beta = gamma = 90 degrees; V = 10431.7(6) Å(3); Z = 8. The central Zn atom is coordinated to the four nitrogen donor atoms and to one oxygen of the bridging carbonate group. In an organic solvent such as DMSO, the complex exists in equilibrium with the decarboxylated Zn(II) complex. In addition, a Zn(II)(cyclen)(ethanol) complex was isolated and characterized by X-ray analysis. Crystal data: monoclinic; space group P2(1)/n; a = 12.707(5), b = 11.780(5), c = 15.642(5) Å; alpha = gamma = 90 degrees; beta = 105.250(5) degrees; V = 2259.0 (6) Å(3); Z = 4. The central Zn atom is coordinated to four nitrogen donor atoms and the oxygen of ethanol. We were not successful in converting this complex to the ethyl carbonate complex. The results of this study are discussed in reference to those published in the literature.

Insights into the Relationship of Catalytic Activity and Structure: A Comparison Study of Three Carbonic Anhydrase Mimics

“…The geometries were fully optimized in solvent using Boese and Martin's τ -dependent hybrid functional, BMK, and a polarizable continuum model (PCM) of solvation [28][29][30]. Based on a diverse and balanced parameterization set including transition metal complexes and hydrogen-bonded systems, the BMK functional was designed to be superior in describing transition state properties as well as atomization energies, geometries, and harmonic frequencies of molecules in the ground state [28,31].…”

Synthesis, structure and magnetism of a μ3-carbonato bridged nickel(II) complex with 2,2′,2″-tris(2-aminoethyl)amine ligand: a new coordination mode of carbonato bridge

“…Since each oxygen atom of the carbonato may act as a monodentate or bidentate ligand, the cabonato binding mode is versatile so that the ligand may coordinate to various kinds of metal ions and produces bi- [4], tri- [1,5], tetra-[6], penta-[7] and even hexanuclear complexes [8]. Of all carbonato bridged complexes reported, most of them are related to copper(II) and zinc(II) ions.…”

Structures of Carbonato and Bicarbonato Complexes of Bis(1,10‐phenanthroline)Zinc(II): Experiment and Theory

“…The coordination polyhedron of the zinc atom can be described as a distorted octahedron. By comparison, in [Cu(phen) 2 (CO 3 )]·7H 2 O the [21,27,28] …”