Synthesis and reactivity of fluorenyl-tethered N-heterocyclic stannylenes

• Published in: Dalton transactions : an international journal of inorganic chemistry 2016-04, Vol.45 (14), p.6282-6293
• Main Authors: Roselló-Merino, Marta, Mansell, Stephen M
• Format: Article
• Language: English
• Subjects: Diamines; Dipping; Equivalence; Ligands; Lithium; Stability; Synthesis; X-rays
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt04060d

A fluorenyl (Fl) tethered diamine was synthesised by nucleophilic substitution of (bromoethyl)fluorene with a diisopropylphenyl (Dipp) substituted diamine to give FlC 2 H 4 N(H)C 2 H 4 N(H)Dipp ( 1a ) in good yield (85%). Lithiation of 1a with n -BuLi proceeded with coordination of the Li cation to the aromatic fluorenide ring ( 2 ), and with subsequent equivalents of n -BuLi, the secondary amines were then sequentially deprotonated. A fluorenyl-tethered N-heterocyclic stannylene (NHSn) was synthesised from the reaction of 1a with SnN′′ 2 {N′′ = N(SiMe 3 ) 2 } as a neutral dimeric species ( 5 ), and this was deprotonated with LiN′′ to give the corresponding dianionic fluorenide-tethered NHSn ( 6 ). Reactions of [{Rh(cod)(μ-Cl)} 2 ] with the mono-deprotonated ligand 2 led to the formation of a mixed-donor amide-amine Rh( i ) compound ( 7 ), whereas reactions with the anionic NHSn 6 led to a Rh-fluorenyl complex of low stability with an uncoordinated pendent NHSn arm, which X-ray crystallography showed to be dimeric in the solid state. N-Heterocyclic stannylenes containing a functionalised donor arm have been synthesised using a transamination strategy from [Sn{N(SiMe 3 ) 2 } 2 ] and fluorenyl-tethered diamines.