This article sets out to review the chemistry relating to the synthesis of structural and functional analogues of the three classes of hydrogenases. This chemistry has grown explosively over the last 10 or so years since the first X-ray structures of [NiFe]- and [FeFe]-hydrogenase systems were published. There are now some 400 papers covering structural and functional aspects, with the majority of these associated with the di-iron system. As much emphasized in earlier papers

Structural and functional analogues of the active sites of the [Fe]-, [NiFe]-, and [FeFe]-hydrogenases.

http://www.chemie.uni-muenchen.de/ac/kluefers/homepage/L/bac/ca_2004.pdf

Synthetic analogues relevant to the structure and function of zinc enzymes.

We report the preparation, structural characterization, and detailed lactide polymerization behavior of a new Zn(II) alkoxide complex, (L1ZnOEt)2 (L1 = 2,4-di-tert-butyl-6-{[(2‘-dimethylaminoethyl)methylamino]methyl}phenolate). While an X-ray crystal structure revealed the complex to be dimeric in the solid state, nuclear magnetic resonance and mass spectrometric analyses showed that the monomeric form L1ZnOEt predominates in solution. The polymerization of lactide using this complex proceeded with good molecular weight control and gave relatively narrow molecular weight distribution polylactide, even at catalyst loadings of <0.1% that yielded Mn as high as 130 kg mol-1. The effect of impurities on the molecular weight of the product polymers was accounted for using a simple model. Detailed kinetic studies of the polymerization reaction enabled integral and nonintegral orders in L1ZnOEt to be distinguished and the empirical rate law to be elucidated, −d[LA]/dt = kp[L1ZnOEt][LA]. These studies also showed ...

A highly active zinc catalyst for the controlled polymerization of lactide.

This paper reviews the tools to manipulate and minimize the band gap of conjugated (co)polymers. The effects of minimization of the bond length alternation and of the incorporation of donor-π-acceptor units are discussed in particular. A systematic study of a series of alternating donor–acceptor oligomers has revealed the achievable limits and allowed for a prognosis of the performance of corresponding copolymers. The decisive influence of the LUMO eigenvectors of the acceptors on the band gap is highlighted. A new synthesis of benzo[1,2-c:4,5-c]bis[1,2,5]thiadiazole containing donor–acceptor monomers and their acid-catalyzed polymerization are described. Finally, band gap tuning by appropriate substitution, conformational adjustment and mesoscopic ordering is discussed.

Developments in the chemistry and band gap engineering of donor-acceptor substituted conjugated polymers

Synthetic routes to zinc β-diiminate complexes are reported. The synthesis of 11 β-diimine [(BDI)-H] ligands, with varying N-aryl substituents and bridging structures, is described. These ligands are converted to (BDI)ZnX complexes (X = OAc, Et, N(SiMe3)2, Br, Cl, OH, OMe, OiPr). X-ray structural data revealed that all zinc complexes examined exist as μ-X-bridged dimers in the solid state, with the exception of the zinc ethyl and amido complexes which were monomeric. Complexes of the form (BDI)ZnOR (R = alkyl, acyl) and (BDI)ZnN(SiMe3)2 are highly active catalysts for the alternating copolymerization of epoxides and CO2. Copolymerizations of cyclohexene oxide (CHO) and CO2 with (BDI-1)ZnX [(BDI-1) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6-diisopropylphenyl)imino)-2-pentene)] and (BDI-2)ZnX [(BDI-2) = 2-((2,6-diethylphenyl)amido)-4-((2,6-diethylphenyl)imino)-2-pentene)], where X = OAc, Et, N(SiMe3)2, Br, Cl, OH, OMe, OiPr, were attempted at 50 °C and 100 psi CO2. Complexes with X = OAc, N(SiMe3)2, OMe, Oi...

Single-site beta-diiminate zinc catalysts for the alternating copolymerization of CO2 and epoxides: catalyst synthesis and unprecedented polymerization activity.

Monomeric Alkyl and Hydride Derivatives of Zinc Supported by Poly(pyrazoly)hydroborato Ligation: Synthetic, Structural, and Reactivity Studies

Poly(sulfur nitride): The First Polymeric Metal

(Tris-(3-tert-butylpyrazolyl)hydroborato)manganese(II), -iron(II), -cobalt(II), and -nickel(II) halide derivatives: facile abstraction of fluoride from tetrafluoroborate(1-)

The monomeric zinc hydride derivative {η3-HB(3-Butpz)3}ZnH has been synthesized by the reaction of ZnH2 with Tl{η3-HB(3-Butpz)3} and its reactivity investigated.

Ian B. Gorrell

Papers

Monomeric Alkyl and Hydride Derivatives of Zinc Supported by Poly(pyrazoly)hydroborato Ligation: Synthetic, Structural, and Reactivity Studies

Poly(sulfur nitride): The First Polymeric Metal

(Tris-(3-tert-butylpyrazolyl)hydroborato)manganese(II), -iron(II), -cobalt(II), and -nickel(II) halide derivatives: facile abstraction of fluoride from tetrafluoroborate(1-)

Tris(3-tert-butylpyrazolyl)hydroborato zinc hydride: synthesis, structure and reactivity of a monomeric zinc hydride derivative

[Bis(3-tert-butylpyrazolyl)hydroborato]zinc alkyl derivatives: competitive reactivity of zinc-carbon and boron-hydrogen bonds