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Structural and Electronic Properties of Neutral Phosphoniobenzo[ c ]phospholides
Author(s) -
Häp Stefan,
Szarvas Laszlo,
Nieger Martin,
Gudat Dietrich
Publication year - 2001
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200111)2001:11<2763::aid-ejic2763>3.0.co;2-v
Subject(s) - chemistry , nanotechnology , stereochemistry , computational chemistry , materials science
The neutral monophosphoniobenzo[ c ]phospholides 2 and 3 were selectively prepared by reduction of bis(triphenylphosphonio)benzophospholide chloride 1 [Cl]. Compound 3 was further converted into the borane adduct 6 and the thioxophosphorane 7 . All products were characterised by spectroscopic methods and X‐ray diffraction. The most notable features of the molecular structures are the significantly different distances of the two P−C bonds adjacent to the two‐coordinate phosphorus atom (P2−C1 175.0−176.6, P2−C3 171.7−173.5 pm), and a short exocyclic C−P(phosphonio) bond (C1−P1 172.5−173.7 pm) relative to cationic derivatives such as 1 . Structure comparisons revealed further variations in the bond lengths, which can be related to the changes in the inductive electron‐withdrawing power of the substituents in the 3‐position of the fused ring system. Computational studies of monophosphoniobenzophospholides, as well as the corresponding anions with no phosphonio substituents, and cations with two phosphonio substituents, allowed for the interpretation of the special properties of the neutral species in terms of a partial π‐bond localisation. This, in terms of a VB picture, is equivalent to the prominence of a single resonance structure that can best be described as an ylide‐substituted cyclic phosphaalkene. The analysis of these results allows important predictions for the chemical properties of these compounds.