79560-59-1Relevant articles and documents
Tris(benzhydryl) and Cationic Bis(benzhydryl) Ln(III) Complexes: Exceptional Thermostability and Catalytic Activity in Olefin Hydroarylation and Hydrobenzylation with Substituted Pyridines
Selikhov, Alexander N.,Boronin, Egor N.,Cherkasov, Anton V.,Fukin, Georgy K.,Shavyrin, Andrey S.,Trifonov, Alexander A.
, p. 5432 - 5443 (2020/10/12)
A series of Ln(III) tris(benzhydryl) complexes [(p-tBu-C6H4)2CH]3Ln (Ln=La (1), Nd (2), Y (3)) were synthesized by the salt metathesis reactions of LnHal3(THF)3.5 (Ln=La, Nd, Hal=Cl; Ln=Y, Hal=I) and [(p-tBu-C6H4)2CH]Na. In 1–3 the benzhydryl ligands are linked with the metal centres in η4-coordination mode. For diamagnetic complexes 1 and 3 a fluxional behaviour was detected in solution. Complexes 1–3 proved to be thermally stable: no decomposition was observed even after heating their solutions in toluene-d8 at 140 °C during 72 h. The reactions of 1 and 2 with B(C6F5)3 allowed for the synthesis of base-free cationic complexes [(p-tBu-C6H4)2CH]2Ln[(p-tBu-C6H4)2CHB(C6F5)3] (Ln=La (4), Nd (5)) which adopt the structure of a contact ion pair. Combinations of 1–3 and borane ((B(C6F5)3, [Me2NHPh][B(C6F5)4], [Ph3C][B(C6F5)4]) as well as 4 and 5 were found to be highly efficient, regio- and chemoselective catalysts for hydroarylation and hydrobenzylation of C=C bonds of a variety of substrates with substituted pyridines. These catalysts enable highly challenging transformations such as hydrobenzylation of 1,1-disubstituted and internal C=C bonds. (Figure presented.).
