[LI2(THF)4DAD] AND [DAD-H][ZRCL5(THF)] - NEW TYPES OF PHENYL-SUBSTITUTED 1,4-DIAZA-1,3-DIENE LIGANDS

Two extreme situations in 1,4-diaza-1,3-diene (DAD) chemistry are described. Reaction of phenyl-substituted DAD 1a - c with lithium in the molecular ratio of 1:2 affords in high yield the extremely air-sensitive complexes [Li2(THF)4DAD] (2a-c). The structure of 2b has been determined by X-ray diffraction. Each of the Li+ ions is coordinated by the two terminal N atoms of the s-cis-configurated DAD dianion and by two molecules of THF. Protonation of ZrCl4 . DAD (3a) by HCl in THF gives the ionic complex [ZrCl5(THF)][DAD - H] (4), which contains a protonated [DAD - H]+ cation. The structure of the sterically crowded N = C - C = N skeleton of the [DAD - H]+ cation is not influenced by the positive charge and adopts the unusual Z-gauche-Z conformation.