Abstract
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.