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1.
iScience ; 7: 120-131, 2018 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-30267674

RESUMO

Neutral zinc alkoxide complexes show high activity toward the ring-opening polymerization of cyclic esters and carbonates, to generate biodegradable plastics applicable in several areas. Herein, we use a ferrocene-chelating heteroscorpionate complex in redox-switchable polymerization reactions, and we show that it is a moderately active catalyst for the ring-opening polymerization of L-lactide, ɛ-caprolactone, trimethylene carbonate, and δ-valerolactone. Uniquely for this type of catalyst, the oxidized complex has a similar polymerization activity as the corresponding reduced compound, but displays significantly different rates of reaction in the case of trimethylene carbonate and δ-valerolactone. Investigations of the oxidized compound suggest the presence of an organic radical rather than an Fe(III) complex. Electronic structure and density functional theory (DFT) calculations were performed to support the proposed electronic states of the catalytic complex and to help explain the observed reactivity differences. The catalyst was also compared with a monomeric phenoxide complex to show the influence of the phosphine-zinc interaction on catalytic properties.

2.
Chem Commun (Camb) ; 51(47): 9643-6, 2015 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-25973852

RESUMO

An indium complex supported by a ferrocene-derived Schiff base ligand has an unprecedented high activity toward ε-caprolactone, δ-valerolactone, and ß-butyrolactone. l-Lactide, d,l-lactide, and trimethylene carbonate polymerizations also showed moderate to high activity.


Assuntos
Ésteres/química , Compostos Ferrosos/química , Índio/química , Compostos Organometálicos/química , Óxidos/química , Polimerização , 4-Butirolactona/análogos & derivados , 4-Butirolactona/química , Caproatos/química , Ciclização , Dioxanos/química , Ácido Láctico/química , Lactonas/química , Metalocenos , Pironas/química , Bases de Schiff/química , Estereoisomerismo
3.
Dalton Trans ; (8): 820-4, 2007 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-17297507

RESUMO

Linear nickel nitrosyl compounds supported by tridentate nitrogen and selenium ligands, namely the tris(3,5-dimethylpyrazolyl)hydroborato and tris(2-seleno-1-mesitylimidazolyl)hydroborato complexes, [TpMe2]NiNO and [TseMes]NiNO, have been synthesized and structurally characterized by X-ray diffraction. Computational studies demonstrate that the linear nitrosyl ligand behaves as a trivalent X3 ligand such that the Ni-N interaction has multiple bond character.


Assuntos
Níquel/química , Compostos Organometálicos/química , Compostos Organosselênicos/química , Cristalografia por Raios X , Ligantes , Modelos Químicos , Estrutura Molecular , Compostos Organometálicos/síntese química , Compostos Organosselênicos/síntese química
4.
Chem Commun (Camb) ; (48): 5015-7, 2006 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-17146512

RESUMO

The dinuclear complex {[mu-kappa(1),kappa(3)-B(mim(Bu(t)))(3)]Pd}(2), which features a Pd-->B dative bond, may be obtained by the reaction of [Tm(Bu(t))]K with Pd(OAc)(2); treatment of {[mu-kappa(1),kappa(3)-B(mim(Bu(t)))(3)]Pd}(2) with PMe(3) affords the mononuclear boratrane derivative [kappa(4)-B(mim(Bu(t)))(3)]Pd(PMe(3)), for which a molecular orbital analysis indicates that the palladium center possesses a d(8) configuration.

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