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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Structures of the radical P[N(SiMe_3)_2](NPr_2~i),its dimer,cation and chloro derivative
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Structures of the radical P[N(SiMe_3)_2](NPr_2~i),its dimer,cation and chloro derivative

机译：自由基P [N（SiMe_3）_2]（NPr_2〜i）的结构，其二聚体，阳离子和氯衍生物

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Treatment of PCl[N(SiMe_3)_2](NPr_2~i) (1) with potassium-graphite in thf afforded the colourless,crystalline diphosphine {P[N(SiMe_3))_2](NPr_2~i)}_2 (2) in good yield.Sublimation of 2 in vacua yielded the yellow phosphinyl radical P[N(SiMe_3)_2](NPr_2~I) (3),which upon cooling reverted to 2;the latter in C_6D_6 at 298 K was a mixture of rac and meso diastereoisomers.The yellow,crystalline phosphenium salt {P[N(SiMe_3)_2](NPr_2~i)}[AlCl_4] (4) was obtained from 1 and 1/2 A1_2C1_6 in CH_2C1_2.By single-crystal X-ray diffraction (XRD) the structures of the known compound 1 and of 2 and 4 were determined.The structure of the radical 3,formed by the thermal homolytic dissociation of the diphosphine 2,was determined in the gas phase by electron diffraction (GED),utilising data from UMP2/6-31+G~* ab initio calculations.The model of the molecule in the GED structure analysis was described by a set of internal coordinates and an initial set of Cartesian coordinates from ab initio calculations,facilitating the structure analysis.The experimental data were found to be consistent with the presence of a single conformer of the radical in the gas phase.The computed standard homolytic dissociation enthalpy of the P-P bond in the corresponding diphosphine 2,corrected for BSSE,54 kJ mol~(-1),is substantially reduced compared to the dissociation enthalpy of tetramethyl-diphosphine by the reorganisation energies of the fragments that form upon dissociation.The intrinsic energy content of the P-P bond in the diphosphine 2 was estimated to be 286 kJ mol~(-1),in agreement with the results of previous work on a series of crowded diphosphines.
机译：用碳酸钾处理PCl [N（SiMe_3）_2]（NPr_2〜i）（1），得到无色结晶二膦{P [N（SiMe_3））_ 2]（NPr_2〜i）} _ 2（2）真空升华2得到黄色次膦酰基基团P [N（SiMe_3）_2]（NPr_2〜I）（3），冷却后恢复为2;后者在298 K的C_6D_6中为rac的混合物黄色和结晶的salt盐{P [N（SiMe_3）_2]（NPr_2〜i）} [AlCl_4]（4）是从CH_2C1_2中的1和1/2 A1_2C1_6中获得的。通过单晶X射线分析衍射（XRD）确定了已知化合物1和2和4的结构。通过电子衍射（GED）在气相中确定了由二膦2的热均相离解形成的自由基3的结构，利用UMP2 / 6-31 + G〜*从头算的数据。通过一组内部坐标和从头算的初始笛卡尔坐标，描述了GED结构分析中的分子模型。实验数据与在气相中存在一个单一的自由基构象是一致的。计算出的相应二膦2中PP键的标准均质分解离解焓经BSSE校正54与四甲基-二膦的离解焓相比，kJ mol〜（-1）大大降低，这是由于在离解时形成的碎片的重组能所致。估计二膦2中PP键的本征能含量为286 kJ mol〜（-1），与先前关于一系列拥挤二膦的研究结果一致。

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