Synthesis and thermal properties of adducts of trimethylindium with nitrogen-containing Lewis bases

Abstract

Adducts of trimethylindium with a range of nitrogen-containing Lewis bases have been prepared, and their thermal properties investigated. No adducts formation is observed with triphenylamine or N,N,N′,N′-tetramethyl-1,8-naphthalenediamine. From Lewis-base solvents such as diethyl ether, volatile 1 : 1 adducts can be isolated with 3,3′-bipyridyl (3,3′-bipy), 4,4′-bipy, 4-dimethylaminopyridine, and N,N,N′,N′-tetramethyl-1,4-phenylenediamine (tmpd), as well as a volatile 2 : 1 (InMe₃: Lewis base) adduct formed with N,N,N′,N′-tetramethylenediamine. In order to prepare 2 : 1 (InMe₃: Lewis base) adducts of 3,3′-, 4,4′-bipy, and tmpd it is necessary to use non-co-ordinating hydrocarbon solvents. Of these, the 3,3′-bipy and tmpd adducts dissociate on heating in vacuo to afford the corresponding 1 : 1 adducts and trimethylindium, whereas the 4,4′-bipy adduct sublimes intact. In both co-ordinating and non-co-ordinating solvents, 2,2′-bipy forms non-stoicheiometric adducts whose properties have not been investigated further. Factors influencing adduct stoicheiometry are discussed.