(162.7–193.1 pm) and vary substantially with small variations in the substituents. The results of quantum mechanical investigations suggest that the origin of the bond elongation is significant in‐plane negative hyperconjugation of lone pairs of the nitrogen substituents with the σ* orbitals of the C−C bonds in o‐carboranes.
                                    一系列1,2-二
氨基的合成Ô -carboranes(1 - 4报道)。这些二
氨基邻
氨基甲酸酯的分子结构非常引人注目,因为内部簇的CC键都是超长的(162.7–193.1 pm),并且取代基的变化很小。量子力学研究的结果表明,键延伸的起源是邻位碳氮烷中氮取代基的孤对与CC键的σ*轨道的显着的面内负超共轭。