Six phosphoric triamides in which amide nitrogens are incorporated into an increasing number (from 0 to 3) of the 1,3,2-diazaphospholidin-2-one rings have been prepared and their crystal structures have been determined. The structural changes from the non-cyclic to the mono-, di- and tri-cyclic systems result in the decrease of the NâPâN bond angles and the increase of the PâN bond distance. These changes are paralleled by a strong deshielding of the 31P nucleus, leading to an exceptionally high δP value for the tricyclic derivative. The δPâstructural parameters relationship is discussed in terms of the changes in hybridization of phosphorus and the variation in the PâN bond order.
合成了六种含
磷三酰胺,其中酰胺氮原子分别引入1,3,2-二氮
磷杂
环戊二酮系统(从0到3个),并测定了它们的晶体结构。从非环系到单环系、二环系和
三环系,N—P—N键角依次减小,而P—N键长增大。这些变化与31P核的去屏蔽作用加强并行,导致
三环系衍
生物的δP值特别高。关于δP与结构参数的关系,曾根据
磷的杂化作用的改变和P—N键级的变化加以讨论。