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An interesting reversible, templated synthesis of unsymmetrical pyridine-ligated Zn complexes has been observed in solution and solid-state phases when Zn(salphen) complexes are reacted with methanol-substituted pyridine substrates. The X-ray molecular structure of an unusual Zn(3) supramolecular assembly is reported, in which the central Zn atom is embedded in a distorted octahedral geometry and each of the single anionic O atoms of the pyridine groups coordinates to a Zn(salphen) unit. 相似文献
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da Costa EC Figueiredo W 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(2):1134-1138
We studied in this work a three-monomer reaction model on one- and two-dimensional lattices. We have taken different reactivity rates among pairs of monomers and the reaction between two selected monomers was forbidden. We have employed the mean field and the pair approximation to decouple the equations of motion for the densities of single and pairs of monomers. We found the stationary states and the phase diagram of the model. We have shown that, in two dimensions and within the pair approximation, there is a first-order transition line between active and poisoned steady states. 相似文献
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da Rocha ZN Ferreira KQ Silva M de Oliveira EC Chiericato G Tfouni E 《Inorganic chemistry》2001,40(21):5385-5392
The synthesis, UV-vis spectra, and electrochemical behavior of the nitrile-bonded trans-[Ru(II)Cl(cyclam)(4-NCpyH(+))](BF(4))(2) (4-Ncpy = 4-cyanopyridine; cyclam = 1,4,8,11-tetraazacyclotetradecane) and of trans-[Ru(III)Cl(cyclam)(NHC(O)-4-pyH(+))](2+) are described. The UV-vis spectrum of the Ru(II) nitrile complex shows a MLCT band at 548 nm at pH 1, which is shifted to 440 nm at pH approximately 6, for the unprotonated species. trans-[Ru(II)Cl(cyclam)(4-NCpyH(+))](2+) was electrolytically oxidized (+600 mV vs Ag/AgCl) at pH 1 to Ru(III), followed by hydrolysis (k = 0.25 s(-1)) of the coordinated nitrile to give trans-[Ru(III)Cl(cyclam)(NHC(O)-4-pyH(+))](2+), in which the amide is deprotonated and coordinated through nitrogen. The identity of the species is pH dependent, the nitrogen-bonded amide prevailing at low pH (< 7), but the oxygen-bonded amide is formed through linkage isomerization at higher pH (>8). Reduction of trans-[Ru(III)Cl(cyclam)(NHC(O)-4-pyH)](2+) in acidic media does not result in fast aquation (k = approximately 2.4 x 10(-5) s(-1)) as for other amides on ruthenium(II) pentaammine, but instead linkage isomerization occurs, resulting in the oxygen-bonded species, with an estimated rate constant of approximately 2 x 10(-2) s(-1), smaller than in the pentaammine analogues. 相似文献
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Gulyás H Benet-Buchholz J Escudero-Adan EC Freixa Z van Leeuwen PW 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(12):3424-3430
An ionic interaction has been used for the first time to assemble monophosphane ligands. NMR spectroscopy and X-ray studies show that cationic and anionic triphenylphosphane derivatives form ion pairs and subsequently act as a ligand in various transition-metal complexes. The position of the ionic functional groups allows both cis and trans coordination of the novel assembly ligand in square-planar transition-metal complexes. 相似文献
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