235754-83-3Relevant academic research and scientific papers
Structural and electronic properties of neutral phoshoniobenzo[c]phospholides
Haep, Stefan,Szarvas, Laszlo,Nieger, Martin,Gudat, Dietrich
, p. 2763 - 2772 (2007/10/03)
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 ?-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 phosphoalkene. The analysis of these results allows important predictions for th chemical properties of these compounds.
Ambident σ- and π-donor ability of a neutral 10π-aromatic phosphoniobenzophospholide
Gudat,Hap,Szarvas,Nieger
, p. 1637 - 1638 (2007/10/03)
1-Triphenylphosphoniobenzo[c]phospholide 2 which is accessible via NaBH4 reduction of 1,3-bis(triphenylphosphonio)benzophospholide 1 displays an ambident coordination ability similar to a phosphinine; this is shown by its reactions with (cyclooctene)Cr(CO)5 and (naphthalene)Cr(CO)3 which gave (σ(P)-2)Cr(CO)5 and (η5-2)Cr(CO)3, the first π-complex of a 10π-aromatic phosphorus heterocycle with a d-block metal.
Reduction of bis(phosphonio)isophosphindolides to phosphane- functionalized benzo[c]phospholides
Gudat, Dietrich,Bajorat, Volker,H?p, Stefan,Nieger, Martin,Schr?der, Gisela
, p. 1169 - 1174 (2007/10/03)
Bis(phosphonio)benzo[c]phospholides (isophosphindolides) 1a,b have been found to react with magnesium or alkali metal naphthalenides MC10H8 (M = Li, Na, K) with reduction of one or both of the phosphonio groups. The main products are the mono- or bis(phosphanyl)-substituted heterocycles 2, 3, 6, 7, which have been characterized by in situ NMR studies and in some cases isolated. Subsequent reaction of 2 with excess [Ni(CO)4] gave the complex 4, which has been characterized by X-ray diffractometry. Reactions of la with alkali metals followed a more complicated course and gave a mixture of 2, 3, and the substitution product 8, which was further reduced to the phosphanido- substituted benzo[c]phospholide 9. The latter could be formed selectively by first converting la into 8 by treatment with PhNa and then treating this with lithium. NMR data of the phosphane-substituted benzo[c]phospholides and the structural features of 4 are discussed.
