Reaktion von (1,4-diazabutadien)bis(alken)nickel(0)-Komplexen mit Ethin

Abstract

The (1,4-diazabutadiene)bis(alkene)nickel(0) complexes ( iPr 2Ph) 2-dadNi(C 2H 4) 2 [( iPr 2Ph) 2-dad = 2,6- iPr 2C 6H 3−NCHCHN−C 6H 3-2,6- iPr 2] ( 1) and ( iPr 2 Ph) 2-dadNi(η 2,η 2-C 6H 10) ( 2) react with ethyne above −100°C ( 1) or −30°C ( 2) with coupling of two ethyne molecules to afford the dinuclear complex [( iPr 2Ph) 2- dadNi] 2(C 4H 4) ( 3) which contains a ferrol-type nickelacyclopentadiene-nickel(0) bonding element. A single-crystal X-ray structure study of 3 revealed strongly distorted coordination geometries of the nickel centers, which are also present in solution at low temperature ( 1H, 13C-NMR). At higher temperatures dynamic processes take place by which the coordinative distortions at the nickel centers are reversed and the bonding situations of the nickel atoms are exchanged. However, a rotation of the phenyl groups around the NC bonds can be excluded. Similarly, [(Me 2Ph) 2-dadNi] 2(C 4H 4) ( 4) has been obtained and characterized.