Lanthanide Complexes Coordinated by a Dianionic Bis(amidinate) Ligand with a Rigid Naphthalene Linker

• Published in: European Journal of Inorganic Chemistry 2010-07, Vol.2010 (21), p.3290-3298
• Main Authors: Yakovenko, Marina V., Cherkasov, Anton V., Fukin, Georgy K., Cui, Dongmei, Trifonov, Alexander A.
• Format: Article
• Language: English
• Subjects: Amidinates; Coordination modes; Lanthanides; Ligand design
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201000330

The synthetic pathway to a new bis(amidine) ligand with a conformationally rigid naphthalene linker, 1,8‐C10H6[NHC(tBu)=N(2,6‐Me2–C6H3)][N=C(tBu)NH(2,6‐Me2–C6H3)] (3) was elaborated. Deprotonation of this bis(amidine) ligand with two equivalents of nBuLi and subsequent reaction with anhydrous LnCl3 (Ln = Y, Nd, Sm) allowed the synthesisof the chlorido complexes [1,8‐C10H6{NC(tBu)N‐2,6‐Me2–C6H3}2]YCl(dme) (4), [1,8‐C10H6{NC(tBu)N‐2,6‐Me2–C6H3}2]Nd(dme)(μ‐Cl)2Li(dme) (5), and [1,8‐C10H6{NC(tBu)N‐2,6‐Me2–C6H3}2]Sm(thf)(μ‐Cl)2Li(thf)2 (6), which are coordinated by the linked dianionic bis(amidinate) ligand. The structures of complexes 4–6 were established by X‐ray diffraction studies, which reveal that the new ligand framework can coordinate to the lanthanide atoms in different fashions depending on the central atom ion size. Alkylation of complex 6 with equimolar amounts of LiCH2SiMe3 afforded the unexpected amido–amidinate complex [{1,8‐C10H6(NC(tBu)N‐2,6‐Me2–C6H3)2}{1,8‐C10H6(NC(tBu)N‐2,6‐Me2–C6H3)(NH)}Sm][Li(dme)3] (7), which obviously results from the cleavage of one amidinate group during decomposition of the transient alkyl species and ligand redistribution. A new dianionic bis(amidinate) ligand framework with a conformationally rigid naphthalene linker was developed andshown to form a suitable coordination environment for lanthanide ions.