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

Treatment of Cp*(CO)2WCNEt2 (1) (Cp*=η5-pentamethylcyclopentadienyl) with HCl affords the aminomethylene complex cis-Cp*(Cl)(CO)2WC(H)NEt2 (2). Complex 2 inserts stereoselectively GeCl2 into the tungsten–chlorine bond to afford cis-Cp*(GeCl3)(CO)2WC(H)NEt2 (3). Complex 3 can also be obtained directly from 1 and GeCl2(diox) (diox=1,4-dioxane) in CH2Cl2. Similarly, treatment of Cp**(CO)2WCNEt2 (1a) (Cp**=η5-ethyltetramethylcyclopentadienyl) with GeCl2(diox) in toluene affords cis-Cp**(GeCl3)(CO)2WC(H)NEt2 (3a). An isomerization equilibrium is established between 3 and trans-Cp*(GeCl3)(CO)2WC(H)NEt2 (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CNEt2 (5) reacts with GeCl2(diox) to yield stereoselectively spy-5-14-Cp*(Cl)(GeCl3)(CO)WCNEt2 (6). Complexes 2–6 were fully characterized and the crystal structures of the complexes 2, 3, 4 and 6 are presented.