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Chemical bonding in phosphonitrilic systems—comparison of the electronic structures of (F 2 PN) 3 , (F 2 PN) 4 , and OP(F 2 )NP(F 2 )NPF 3
Author(s) -
Ferris Kim F.,
Duke C. B.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560360843
Subject(s) - chemistry , electronic structure , phosphazene , electronegativity , molecule , chemical bond , delocalized electron , molecular orbital , bond length , computational chemistry , crystallography , ab initio , molecular orbital theory , chemical physics , crystal structure , polymer , organic chemistry
The electronic structure of phosphonitrilic systems contain both π′ (in‐plane) and π (out‐of‐plane) bonding systems. Earlier work in this laboratory has indicated that the d‐orbital involvement in these systems affects primarily the electronic structure, and is modulated by ligand electronegativity. Ab initio molecular orbital calculations were performed on a series of small phosphazene molecules [(F 2 PN) 3 , (F 2 PN) 4 , and OP(F 2 )NP(F 2 )NPF 3 ] to elucidate the electronic and molecular structure of these molecules as models for polymeric systems. The chemical bonding and charge distribution in the phosphonitrilic trimers, tetramers, and these small fragments is highly polarized, primarily through the π and π′ bonding networks. Our results indicate that while the majority of the electronic aspects of OP(F 2 )NP(F 2 )NPF 3 can be described by analogies to (F 2 PN) 3 and (F 2 PN) 4 , major geometric differences such as bond alternation are evident. The opening of the P—N—P bond angles in the linear fragment results in reduced overlap over multiple centers, promoting “islands of delocalization” first proposed by Dewar et al. [1].