Abstract Di, tri, tetra and pentacyclophosphazenes substituted on the phosphorus atoms by CH3, F, Cl and Br atoms corresponding to (X2PN)n structures have been studied theoretically at the B3LYP/6-311++G(d,p) level. After a brief discussion of their geometries comparing them to those of the conjugated carbocycles, (CH)n, of the same size, the absolute shieldings calculated with the GIAO and ZORA approximations will be reported. For the Cl and mainly for the Br substituted cyclo[n]-phosphazenes, relativistic corrections are absolutely necessary for 31P and useful for 15N chemical shifts. GRAPHICAL ABSTRACT

中文翻译：

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n = 2、3、4 和 5 (X2PN)n 的环 [n] 磷腈化学位移的理论计算，其中 X = CH3、F、Cl 和 Br：相对论修正的影响

摘要 已在 B3LYP/6-311++G(d,p) 水平对对应于 (X2PN)n 结构的 CH3、F、Cl 和 Br 原子取代磷原子上的二、三、四和五环磷腈进行了理论研究。在简要讨论它们的几何形状并将它们与相同尺寸的共轭碳环 (CH)n 的几何形状进行比较后，将报告使用 GIAO 和 ZORA 近似计算的绝对屏蔽。对于 Cl 和主要是 Br 取代的环 [n]-磷腈，相对论校正对于 31P 和 15N 化学位移是绝对必要的。图形概要