Heteroleptic lanthanide amide complexes bearing carbon-bridged bis(phenolate) ligands: synthesis, structure and their application in the polymerization of ε-caprolactone

A convenient method for the synthesis of anionic lanthanide amide complexes bearing carbon-bridged bis(phenolate) ligands is described and the catalytic activity of the complexes in the ring-opening polymerization of ε-caprolactone was studied.

Uranium-mediated ring-opening polymerization of ε-caprolactone: a comparative study

This study shows and compares the catalytic activity and the mechanism of the uranium complexes [(Im^DippN)₂U(NMeEt)₂] (3), [(C₅Me₅)₂U(NMe₂)₂] (4) and [(C₅Me₅)₂U(NCMePh)₂] (5) in the ring-opening polymerization of ε-caprolactone, among which the bis(imidazolin-2-iminato) uranium complex3displayed the highest catalytic activity.

N-Benzoylbenzamidinate complexes of aluminium: highly efficient initiators for the ring-opening polymerization of ε-caprolactone

A series of aluminium complexes supported by amidinate-based N,O-chelate ligands are synthesized and characterized. While complexes [L(Dipp)AlMe2] () and [L(Ph)AlMe2] () are prepared by treating N-benzoyl-N'-2,6-diisopropylphenylbenzamidine (L(Dipp)H) and N-benzoyl-N'-phenylbenzamidine (L(Ph)H) with a slight excess of 1 equiv. of AlMe3, complexes [(L(Dipp))2AlMe] () and [(L(Ph))3Al] () can be obtained using the ligands and AlMe3 in 2 : 1 and 3 : 1 molar ratios respectively. Complexes have been characterized by (1)H/(13)C NMR spectroscopy and elemental analysis. The molecular structures of complexes , and have also been determined by single crystal X-ray diffraction technique. , and are highly active initiators for the ring opening polymerization (ROP) of ε-caprolactone and produce polycaprolactone with very high molecular weight and narrow molecular weight distribution. These complexes are also active toward the ROP of cyclohexene oxide.

Synthesis and structural characterization of novel tetranuclear organotitanoxane derivatives

Synthesis of the novel titanoxane compounds, [(TiCl)(TiOH){(Ti)[μ-(η(5)-C(5)Me(4)SiMe(2)O-κO)](2)(μ-O)}(2)(μ-O)] (4) and [{Ti[μ-(η(5)-C(5)Me(4)SiMe(2)O-κO)](μ-O)}(4)] (5) by controlled reaction of the dinuclear titanium oxo complex [{Ti{μ-(η(5)-C(5)Me(4)SiMe(2)O-κO)}Cl](2)(μ-O)] (1) with 2 equiv of LiOH is reported. Complex 4 is innovative and remarkable. It is one of the rare known examples of tetranuclear stable terminal hydroxo titanium complexes, with an open-chained structure, which coincides with the transient metal monohydroxo proposed in the stepwise pathway employed to justify the formation of the hexanuclear complex [{Ti[μ-(η(5)-C(5)Me(4)SiMe(2)O-κO)](μ-O)}(6)] (3) from 1. (1)H DOSY experiments were used to characterize complex 4. In addition, the structures of compound 5 and of precursor 1 were determined by single-crystal X-ray diffraction studies.