Yttrium-Alkyl Complexes Supported by a Ferrocene-Based Phosphinimine Ligand

Brosmer, Jonathan L.; Diaconescu, Paula L.

doi:10.1021/om501227t

Cited by 22 publications

(9 citation statements)

References 70 publications

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“…The Y–C1 and Y–C4 distances were 2.504(4) and 2.489(5) Å, respectively. The Fe–Y distance of 3.406(1) Å is outside the range of the sum of the covalent radii, 3.22 Å, indicating the absence of an iron–yttrium interaction in this compound. ,− ,− Interestingly, the C1–C2 and C3–C4 distances were 1.357(7) and 1.340(1) Å, respectively, indicating the presence of double bonds. The C2–C3 distance of 1.512(6) Å is representative of a single bond.…”

Section: Resultsmentioning

confidence: 89%

Reduction of Diphenylacetylene Mediated by Rare-Earth Ferrocene Diamide Complexes

2017

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The synthesis and characterization of Ln-C 4 Ph 4 -K, [(NN TBS )Ln(η 2 -C 4 Ph 4 )][K(THF) x ] (Ln = Sc, Y, Lu), rareearth metal complexes supported by a ferrocene diamide ligand, NN TBS (NN TBS = fc(NSi t BuMe 2 ) 2 , fc = 1,1′-ferrocenediyl), were accomplished. The preparation of the half-sandwich compounds, Ln-naph-K, [(NN TBS )Ln(μ-C 10 H 8 )][K(THF) 2 ] (Ln = Sc, Y, Lu, La), was necessary in order to obtain high yields of rare-earth metallacyclopentadienes. Unlike Y and Lu, La did not show the same reactivity toward PhCCPh. The characterization of the new metal complexes was accomplished by NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction.

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Section: Resultsmentioning

confidence: 89%

Reduction of Diphenylacetylene Mediated by Rare-Earth Ferrocene Diamide Complexes

2017

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“…However, in the case of the reduced species, a direct zinc-phosphine interaction was not observed. Despite this finding, and because of our interest in redox-switchable catalytic processes ( Abubekerov et al., 2016 , Abubekerov et al., 2017 , Wang et al., 2014 , Wang et al., 2015 , Quan and Diaconescu, 2015 , Brosmer and Diaconescu, 2015 , Abubekerov and Diaconescu, 2015 , Upton et al., 2014 , Broderick et al., 2011a , Broderick et al., 2011b , Broderick et al., 2011c , Quan et al., 2016 , Quan et al., 2017 , Lowe et al., 2017 , Shepard and Diaconescu, 2016 ), we set out to investigate the influence of the redox state of fc P,B on the zinc-mediated ring-opening polymerization of cyclic esters and carbonates. In addition, an investigation into the redox and polymerization activity of a monomeric ferrocene-chelating heteroscorpionate zinc complex, (fc P,B )Zn(OPh), is reported.…”

Section: Introductionmentioning

confidence: 99%

Exploring Oxidation State-Dependent Selectivity in Polymerization of Cyclic Esters and Carbonates with Zinc(II) Complexes

et al. 2018

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SummaryNeutral 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.

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“…In 2011, our group applied a redox switchable strategy to the ring-opening polymerization of different monomers by switching between the oxidized and reduced forms of a catalyst . Since then, important progress in the area of switchable polymerization has been made by our group and others. − Via appropriate sequential catalyst oxidation and reduction, several types of diblock copolymers, such as PCL–PLA and PLA–PCHO, could be prepared. However, the substrate scope is still limited, and the selectivity of the oxidized and reduced forms of the catalysts remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Redox Control of Aluminum Ring-Opening Polymerization: A Combined Experimental and DFT Investigation

2017

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ABSTRACT:The synthesis, characterization, and reactivity of an aluminum alkoxide complex supported by a ferrocene-based ligand, (thiolfan*)Al(O t Bu) (1 red , thiolfan* = 1,1'-di(2,4-di-tert-butyl-6-thiophenoxy)ferrocene), are reported. The homopolymers of L-lactide (LA), ε-caprolactone (CL), δ-valerolactone (VL), cyclohexene oxide (CHO), trimethylene carbonate (TMC), and their copolymers were obtained in a controlled manner by using redox reagents. Detailed DFT calculations and experimental studies were performed to investigate the mechanism. Mechanistic studies show that after the insertion of the first monomer, the coordination effect of the carbonyl group, which has usually been ignored in previous reports, can significantly change the energy barrier of the propagation steps, thus playing an important role in polymerization and copolymerization processes.

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Yttrium-Alkyl Complexes Supported by a Ferrocene-Based Phosphinimine Ligand

Cited by 22 publications

References 70 publications

Reduction of Diphenylacetylene Mediated by Rare-Earth Ferrocene Diamide Complexes

Reduction of Diphenylacetylene Mediated by Rare-Earth Ferrocene Diamide Complexes

Exploring Oxidation State-Dependent Selectivity in Polymerization of Cyclic Esters and Carbonates with Zinc(II) Complexes

Redox Control of Aluminum Ring-Opening Polymerization: A Combined Experimental and DFT Investigation

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