Sc and Y Heteroalkyl Complexes with a NCsp3N Pincer‐Type Diphenylmethanido Ligand: Synthesis, Structure, and Reactivity

• Published in: European journal of inorganic chemistry 2020-09, Vol.2020 (34), p.3259-3267
• Main Authors: Fayoumi, Ahmad, Lyubov, Dmitry M., Tolpygin, Alexey O., Shavyrin, Andrey S., Cherkasov, Anton V., Ob'edkov, Anatoly M., Trifonov, Alexander A.
• Format: Article
• Language: English
• Subjects: Alkenes; Alkyl complexes; Alkynes; Aromatic compounds; Coordination compounds; Cross coupling; Diphenylmethanides; Hydrosilylation; Inorganic chemistry; Isoprene; Ligands; Palladium; Pincer ligands; Rare earths; Structure elucidation
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202000306

New diphenylmethane [4‐tBu‐2‐(C3H2N2Me‐1)C6H3]2CH2 (1) bearing pendant imidazolyl groups in ortho‐positions of aromatic rings of diphenylmethane skeleton was synthesized using Stille cross‐coupling reaction between bis(4‐(tert‐butyl)‐2‐iodophenyl)methane and Bu3Sn(C3H2N2Me) in the presence of Pd(PPh3)4. Potassium diphenylmethanide [{[4‐tBu‐2‐(C3H2N2Me‐1)C6H3]2CH}K(OEt2)]2 (2K) was prepared by treatment of 1 with an equimolar amount of Lochmann‐Schlosser super base. Rare‐earth metal heteroalkyl complexes {[4‐tBu‐2‐(C3H2N2Me‐1)C6H3]2CH}Ln(CH2SiMe3)2(THF)n (Ln = Sc, n = 0 (2Sc); Y, n = 1 (2Y)) with NCsp3N pincer type diphenylmethanido ligand were synthesized by the selective sp3 CH‐bond activation of the central CH2 group in 1 by Ln(CH2SiMe3)3(THF)2. According to the X‐ray data the diphenylmethanido ligands in 2K and 2Sc perform a tridentate pincer‐type κ3‐N,C,N coordination. Complexes 2Ln were evaluated as catalysts for isoprene polymerization and hydrosilylation of alkenes and alkynes. Thermally stable heteroleptic tri(alkyl) rare‐earth metal complexes [NCsp3N]Ln(CH2SiMe3)2(THF)n (Ln = Sc, Y) containing the NCsp3N pincer diphenylmethanido ligand were synthesized through selective Csp3–H bond activation of the central CH2 group of imidazolyl‐substituted diphenylmethane. Incorporation of the NCsp3N pincer diphenylmethanido ligand provides stability and at the same time maintains the high reactivity of these heteroleptic tri(alkyl)s.