The thorium methyl and hydride complex (C5Me5)2ThMe2 and [(C5Me5)2Th­(H)­(μ-H)]2 catalyzed highly 1,2-regioselective dearomatization of pyridines via a hydroboration process is reported herein. Twelve different kinds of meta- and para-substituted pyridines are applicable to this reaction, giving the corresponding N-boryl-1,2-dihydropyridine products in high yields. Other N-heteroaromatic compounds, such as benzo-fused N-heterocycles, pyrazines, pyrimidines, 1,3,5-triazine, and benzothiazole, were also found to be hydroborated with high chemoselectivity. Kinetics including isotope effect studies revealed a first-order dependence on the concentration of catalyst, pyridine, and pinacolborane, with release of the dearomatized final product as the rate-determining step. A plausible mechanism is proposed on the basis of stoichiometric reactions and kinetic studies.

The insertion of alcohols into carbodiimides mediated by benzimidazolin-2-iminato actinide complexes [(BimN)AnN″] [N″ = N(SiMe)] is presented herein. Analysis of single-crystal data revealed that steric hindrance, rather than electronic properties, plays an important role in determining the accessibility for this insertion process. All actinide complexes showed excellent activities under very mild conditions. Stoichiometric reactions in combination with kinetic and thermodynamic studies allow us to propose a plausible active species and a mechanism for the catalytic cycle.

This study shows and compares the catalytic activity and the mechanism of the uranium complexes [(ImDippN)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.

Imidazolin‐2‐iminato hafnium complexes of the type [(ImRN)Hf(CH2Ph)3] were synthesized (ImtBuN = 1,3‐di‐tert‐butylimidazolin‐2‐iminato); ImDippN = 1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐iminato. The complexes were crystallized and structurally characterized. Despite the oxophilicity of the hafnium center, both hafnium complexes were catalytically active in the hydroboration of aldehydes, ketones, and carbodiimides. Herein, we present the influence of different substrates bearing electron‐withdrawing or electron‐donating groups on the catalytic reactions. Based on stoichiometric reaction in each process, plausible mechanistic scenarios are presented.