已经通过吡啶-2-硫代氧羰基(PTOC)竞争动力学方法在单个浓度点上确定了壬基从20种N-杂环卡宾和硼烷(NHC-硼烷)的络合物中提取氢的速率常数。速率常数的范围是从<1×10 4到8×10 4 M -1 s -1。它们几乎不依赖于卡宾核的电子性质,但是存在随着卡宾N取代基尺寸的减小而增加速率常数的趋势。已经鉴定出两种有希望的具有小的N取代基的新试剂(R = Me)。
A versatile new method for the preparation of NHC boranes starting from two stable, readily available reactants―an heterocyclic salt and an amine or phosphine−borane―is reported. It uses a Lewis base exchange at boron and provides easy access to new NHC boranes, in particular B-substituted borane ones.