Insertion of Carbenes into Deprotonated nido -Undecaborane, B 11 H 13 (2-).

We have examined the insertion of carbenes carrying leaving groups into the [ nido -B ₁₁ H ₁₃ ] ^2- dianion to form the [ closo -1-CB ₁₁ H ₁₂ ] ^- anion. The best procedure uses CF ₃ SiMe ₃ and LiCl as the source of CF ₂ . It is simple, convenient and scalable and proceeds with 70-90% yield. Density functional calculations have been used to develop a mechanistic proposal that accounts for the different behavior of CF ₂ , requiring only one equivalent of base for successful conversion of Na[ nido -B ₁₁ H ₁₄ ] ^- to [ closo -1-CB ₁₁ H ₁₂ ] ^- , and CCl ₂ and CBr ₂ , which require more.