Lanthanide borohydrides supported by an ansa-bis(amidinate) ligand with a rigid naphthalene linker: Synthesis, structure and catalytic activity in ring-opening polymerization of lactide

Rare-earth complexes supported by an ansa-bis(amidinate) ligand with a rigid o-phenylene linker: synthesis, structure, and catalytic activity for polymerization of cyclic esters

A bis(amidinate) ligand with a rigid o-phenylene linker C₆H₄-1,2-[NC(^tBu)NH(C₆H₅)]₂ (1) was successfully employed for the syntheses of rare-earth amides 2-5 in good yields. The structures of the amides were established by X-ray diffraction analysis and revealed that the ligand framework coordinated to the lanthanide atoms in different fashions depending on the central ion size. Larger lanthanide metal ions La³⁺ and Nd³⁺ prefer to form dinuclear complexes with one linked bis(amidinate) ligand as a bridge, while the smaller sized Y³⁺ and Er³⁺ favor the formation of mononuclear complexes. These complexes exhibited good catalytic activity for ring-opening polymerization of ε-caprolactone and l-lactide and the mononuclear complexes display higher activity.

Mono- and bimetallic amidinate samarium complexes - synthesis, structure, and hydroamination catalysis

In order to investigate the difference between mono- and bimetallic systems in the catalytic hydroamination/cyclization reaction two mono- and bimetallic amidinate samarium catalysts, featuring comparable coordination environments, were synthesized. Both systems comprise two {N(SiMe₃)₂}^- leaving groups to minimize the steric influence of the corresponding amidinate ligand. The bimetallic system is based on a bis(amidinate) 4,6-dibenzofuran derivative, while N,N'-bis(2,6-diisopropylphenyl)benzamidinate was employed as ligand for the monometallic catalyst. For the hydroamination/cyclization reaction five different substrates were investigated. Additionally, kinetic studies were carried out to gain deeper understanding of the mechanism.

Syntheses and Structures of a Class of Bridged Bis(Amidinate)s and Derivatives

A series of different types of ‘bridge’ linked bis(amidinate)s have been prepared. Reactions of a variety of linked diamines with pivaloyl chloride yielded the corresponding diamides in very high yields. Conversion of the diamides to the diimine chloride is achieved with PCl5 in CH2Cl2. Reactions of the diimine chloride with aniline or t-butyl amine yielded the bis(amidinate)s in good yields, while reaction with pyrrolyl sodium or 2,5-dimethyl pyrrolyl potassium afforded the corresponding derivatives. Their structures were characterised by NMR and HRMS, and some products were further characterised by X-ray crystal structure analysis. It was found that the locations of the hydrogen atoms within the two amidine fragments vary. The structures showed that in the phenylene-linked bis(amidinate)s, the hydrogen atoms were attached to different nitrogen atoms in the amidine groups, and in the cyclohexylene-linked bis(amidinate)s or their derivatives, the C=N of the amidine groups were conjugated with the aromatic rings.

Rare-earth metal-mediated PhCN insertion into N,N-bis(trimethylsilyl)naphthalene-1,8-diamido dianion – a synthetic approach to complexes coordinated by ansa-bridged amido-amidinato ligand

We report the first example of rare earth metal-mediated insertion of PhCN into Si–N bonds with the formation of an amidinato moiety.

Bis(amidinate) ligands in early lanthanide chemistry – synthesis, structures, and hydroamination catalysis

Bis(amidinate) ligands attached to rigid dibenzofuran and phenanthrene backbones have been introduced into lanthanide chemistry for the first time.

Amido rare-earth complexes supported by an ansa bis(amidinate) ligand with a rigid 1,8-naphthalene linker: synthesis, structures and catalytic activity in rac-lactide polymerization and hydrophosphonylation of carbonyl compounds

We report the synthesis of rare-earth amides and their catalytic activity in ROP of lactide.