TRIMETHYLGALLIUM-INDUCED TRIMERIZATION OF ACETONITRILE

The reaction of GaMe3 in acetonitrile in the presence of halide ions, F-, Cl-, and Br-, at 60 °C gives the heterocycle [Me2Ga{HNC(Me)}2C(CN)] (1). Further reaction with GaMe3 and MeCN leads to a hexanuclear gallium complex [(Me2Ga)4(MeGa)2{HNC(Me)C(CN)CH(NCMe)2}2] (2). In addition to 2, 2·3MeCN and 2·2GaMe3 can be obtained under special conditions. 1 and 2 have been characterized by their NMR, IR, and MS spectra. X-ray analyses were performed with 1, 2, 2·3MeCN, and 2·2GaMe3. Compound 1 consists of six-membered heterocycles, which are connected by hydrogen bridges to zigzag chains along the direction [010]. 2 contains 10 units of acetonitrile and six gallium centers forming a centrosymmetric eight-membered Ga−N ring. The structure of 2·3MeCN exhibits two hydrogen-bridged MeCN molecules and one acetonitrile molecule which is not connected to another component of the unit cell. In 2·2GaMe3 two units of GaMe3 are coordinated to the CN groups of 2 creating weakly pyramidalized GaMe3 fragments.