Stereoselective insertion of GeCl2 into tungsten–chlorine bonds of aminomethylene and aminocarbyne complexes

Abstract Treatment of Cp*(CO) 2 WCNEt 2 ( 1 ) (Cp*=η 5 -pentamethylcyclopentadienyl) with HCl affords the aminomethylene complex cis -Cp*(Cl)(CO) 2 WC(H)NEt 2 ( 2 ). Complex 2 inserts stereoselectively GeCl 2 into the tungsten–chlorine bond to afford cis -Cp*(GeCl 3 )(CO) 2 WC(H)NEt 2 ( 3 ). Complex 3 can also be obtained directly from 1 and GeCl 2 (diox) (diox=1,4-dioxane) in CH 2 Cl 2 . Similarly, treatment of Cp**(CO) 2 WCNEt 2 ( 1a ) (Cp**=η 5 -ethyltetramethylcyclopentadienyl) with GeCl 2 (diox) in toluene affords cis -Cp**(GeCl 3 )(CO) 2 WC(H)NEt 2 ( 3a ). An isomerization equilibrium is established between 3 and trans -Cp*(GeCl 3 )(CO) 2 WC(H)NEt 2 ( 4 ) in the melt (208°C), which favors the trans isomer ( 3 : 4 ratio=1:6). The aminocarbyne complex cis -Cp*(Cl) 2 (CO)WCNEt 2 ( 5 ) reacts with GeCl 2 (diox) to yield stereoselectively spy -5-14-Cp*(Cl)(GeCl 3 )(CO)WCNEt 2 ( 6 ). Complexes 2 – 6 were fully characterized and the crystal structures of the complexes 2 , 3 , 4 and 6 are presented.