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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Properties of Cationic Pnicogen-Bonded Complexes F4-nHnP+:N-Base with F-P center dot center dot center dot N Linear and n=0-3
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Properties of Cationic Pnicogen-Bonded Complexes F4-nHnP+:N-Base with F-P center dot center dot center dot N Linear and n=0-3

机译：具有P-P中心点中心点中心点N线性和n = 0-3的阳离子Pnicogen键合配合物F4-nHnP +：N-基的性质

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摘要

Ab initio MP2/aug'-cc-pVTZ calculations were performed to investigate the pnicogen-bonded complexes F4-nHnP+:N-base, for n = 0-3, each with a linear or nearly linear F-P center dot center dot center dot N alignment. The nitrogen bases include the sp(3) bases NH3, NClH2, NFH2, NCl2H, NCl3, NFCl2, NF2H, NF2Cl, and NF3 and the sp bases NCNH2, NCCH3, NP, NCOH, NCCl, NCH, NCF, NCCN, and N-2. The binding energies vary between -20 and -180 kJ.mol(-1), while the P-N distances vary from 1.89 to 3.01 angstrom. In each series of complexes, binding energies decrease exponentially as the P-N distance increases, provided that complexes with sp(3) and sp hybridized bases are treated separately. Different patterns are observed for the change in the binding energies of complexes with a particular base as the number of F atoms in the acid changes. Thus, the particular acid-base pair is a factor in determining the binding energies of these complexes. Three different charge-transfer interactions stabilize these complexes. These arise from the nitrogen lone pair to the sigma*P-F-ax, sigma*P-F-eq, and sigma*P-H-eq orbitals. The dominant single charge-transfer energy in all complexes is N-1p --> sigma*P-F-ax. However, since there are three N-1p --> sigma*P-F-eq charge-transfer interactions in complexes with F4P+ and two in complexes with F3HP+, the sum of the N-1p--> sigma*P-F-eq charge-transfer energies is greater than the N-1p --> sigma*P-F-ax charge-transfer energies in the former complexes, and similar to the N-1p --> sigma*P-F-ax energies in the latter. The total charge-transfer energies of all complexes decrease exponentially as the P-N distance increases. Coupling constants (1p)J(P-N) across the pnicogen bond vary with the P-N distance, but different patterns are observed for complexes with F4P+ and complexes of the sp(3) bases with F3HP+. These initially increase as the P-N distance decreases, reach a maximum, and then decrease with decreasing P-N distance as the P center dot center dot center dot N bond acquires increased covalent character. For the remaining complexes, (1p)J(P-N) increases with decreasing P-N distance. Complexation increases the P-F-ax distance and (1)J(P-F-ax) relative to the corresponding isolated ion. (1)J(P-F-ax) correlates quadratically with the P-N distance.
机译：从头开始进行MP2 / aug'-cc-pVTZ计算，以研究与p成原结合的复合物F4-nHnP +：N-基，n = 0-3，每个复合物具有线性或近似线性FP中心点中心点中心点N对准。氮碱基包括sp（3）NH3，NClH2，NFH2，NCl2H，NCl3，NFCl2，NF2H，NF2Cl和NF3以及sp碱基NCNH2，NCCH3，NP，NCOH，NCCl，NCH，NCF，NCCN和N -2。结合能在-20至-180 kJ.mol（-1）之间变化，而P-N距离在1.89至3.01埃之间变化。在每个系列的配合物中，结合能随P-N距离的增加呈指数下降，但前提是分别处理带有sp（3）和sp杂交碱基的配合物。随着酸中F原子数的变化，观察到了具有特定碱的配合物结合能变化的不同模式。因此，特定的酸-碱对是确定这些络合物的结合能的因素。三种不同的电荷转移相互作用使这些配合物稳定。它们来自于sigma * P-F-ax，sigma * P-F-eq和sigma * P-H-eq轨道的氮孤对。在所有配合物中，主要的单电荷转移能量为N-1p-> sigma * P-F-ax。但是，由于在与F4P +的复合物中存在三个N-1p-> sigma * PF-eq电荷转移相互作用，在与F3HP +的复合物中存在两个N-1p-> sigma * PF-eq电荷转移相互作用，因此N-1p-> sigma * PF-eq电荷转移的总和前者的能量大于N-1p-> sigma * PF-ax的电荷转移能量，类似于后者的N-1p-> sigma * PF-ax的能量。随着P-N距离的增加，所有配合物的总电荷转移能量呈指数下降。沿p-N距离的耦合常数（1p）J（P-N）随P-N距离而变化，但观察到与F4P +的复合物以及sp（3）碱基与F3HP +的复合物的模式不同。随着P-N距离的减小，这些值最初增加，达到最大值，然后随着P-N距离的减小而减小，因为P中心点中心点中心点N键获得增加的共价特性。对于其余的络合物，（1p）J（P-N）随着P-N距离的减小而增加。络合增加了P-F-ax的距离和相对于相应的离解离子的（1）J（P-F-ax）。 （1）J（P-F-ax）与P-N距离平方相关。

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