Titanocene and Zirconocene Complexes with Diaminoacetylenes: Formation of Unusual Metallacycles and Fulvene Complexes

摘要: The reaction of dipiperidinoacetylene (pipC≡Cpip, pip = NC5H10, 1a) with [Cp2Ti(η2-btmsa)] (2) or [Cp2Zr(η2-btmsa)(py)] (4) (btmsa bis(trimethylsilyl)acetylene, py pyridine) afforded the metallacyclopentadienes [Cp2M(C4pip4)] (3, M Ti; 5, Zr), which in solid state exhibit twisted five-membered metallacycles an unusual half-chair conformation. In contrast, sterically more demanding decamethyltitanocene (Cp*2Ti) and -zirconocene (Cp*2Zr) complex fragments can only accommodate one alkyne ligand. Thus, titanacyclopropene [Cp*2Ti(C2pip2)] (7) was isolated from 1a [Cp*2Ti(η2-btmsa)] (6) [Cp*2TiCl] presence magnesium, whereas zirconacyclopropenes [Cp*2Zr(C2X2)] (8a, X pip; 8b, NC5H9-4-Me; 8c, NEt2) were prepared by reduction [Cp*2ZrCl2] magnesium 1a, bis(4-methylpiperidino)acetylene (1b), bis(diethylamino)acetylene (1c), respectively. NMR studies showed that complexes 8 are equilibrium ...