引言第五、六族元素的鎓离子(onium)与阴碳离子形成的内盐称为叶立德(ylid),例如Me_3N—CH_2、Ph_3P—CH_2、Me_2S—CH_2等。目前已发现氮、磷、砷、锑、硫皆可形成叶立德,硒、碲的叶立德尚未见报导。氧能不能形成叶立德,尚成问题,估计其稳定性是很小的。叶立德中有关原子的d-轨道如能参加键合,例如Ph_3P—CH_2(?)Ph_3P=CH_2,则该叶立德更为稳定。近年来,叶立德化学的发展至为迅速, Introduction The inner salts formed by the onium and the carbanions of the fifth and sixth group elements are referred to as ylid, such as Me_3N-CH_2, Ph_3P-CH_2, Me_2S-CH_2 and the like. It has been found that nitrogen, phosphorus, arsenic, antimony, sulfur Yeleide can be formed, selenium, telluride Ye Lide has not been reported. Oxygen can not form Ye Lide, still a problem, it is estimated that the stability is very small. The Yellde is more stable with respect to the d-orbit of the atom in the Yeldde if it participates in a bond such as Ph_3P-CH_2 (?) Ph_3P = CH_2. In recent years, the rapid development of Ye Lide chemistry,