Induction of Chirotopicity in the Self-Assembly Process of Heterocuprates: Structural and Stereochemical Aspects of Neutral CuLi2BrAryl2 Aggregates

Abstract

Self-assembling reactions of the ortho-diamine chelated aryllithium dimers of type [Li(C∧N∧N‘)]2 with 1 equiv of CuBr resulted in the selective formation of hetero cuprates 1, 2, 3a, and 3b, respectively, which all have [CuLi2Br(C∧N∧N‘)2] stoichiometry (C∧N∧N‘ = Ar, [C6H4(CH2N(Me)CH2CH2NMe2)-2]- (1); Naph, [1-C10H6(CH2N(Me)CH2CH2NMe2)-2]- (2); (R)-Ar, (R)-[C6H4(CH(Me)N(Me)CH2CH2NMe2)-2]- (3a); or rac-Ar, rac-[C6H4(CH(Me)N(Me)CH2CH2NMe2)-2]- (3b)). The structure of 1 and 2 in the solid state comprises [(C∧N∧N‘)2Cu]- and [Li2Br]+ fragments which are joined by intramolecular N,N‘-chelation of the ortho-diamine ligand to lithium, thus forming an, overall neutral, 2:1 cuprate species. The coordinated benzylic nitrogen centers (NMe) in these trinuclear CuLi2 aggregates have a stable configuration, RN or SN. In fact, 1 and 2 exist in the solid state as RNRN and SNSN diastereoisomers, respectively. Accordingly, the halocuprates 1 and 2 can serve as model complexes for investigation of the structure of correspondi...