The Presence of [Ar2Cu]- and [(RC=C)2Cu]- Homocuprate Moieties in the Neutral Mixed Cuprate [Cu2Li2(C=CR)2Ar2] (Ar = C6H4{CH2N(Me)CH2CH2NMe2}-2; R = C6H4Me-4 or C6H4SiMe3-4)

Abstract

The neutral, mixed 2:2 aryl-alkynyl-cuprates [Cu2Li2(CCR)2Ar2] (Ar = [C6H4{CH2N(Me)CH2CH2NMe2}-2]-; R = C6H4Me-4 (3a) or C6H4SiMe3-4 (3b)) are the first examples of cuprates that contain two different organic homocuprate parts ([Ar-Cu-Ar]- and [(RCC)-Cu-(CCR)]-) in one assembled structure. Each part has a two-coordinate Cu atom in linear geometry. They are held together by Li-Cipso interactions to two Li atoms. Tetrahedral four-coordination at the Li centers is completed by N,N'-chelation of the ortho-diamine substituent of the Ar ligand. Compound 3 is formed as the only reaction product in almost quantitative yield when LiAr and Cu(CCR) aggregates are mixed together in equimolar amounts. This cuprate is an example of ion-pairing between two different homocuprate anions and two Li cations.