Phospholides

The half-sandwich and sandwich complexes of phospholides and phosphole tetramer are known even for the nontransition metals. The half-sandwich arrangement was studied for lithium tetramethylphospholide [89AG(E)1367] and sodium derivative 127 generated from the phospholide tetramer and sodium in the presence of 1,2-dimethoxyethane [94JA3306 96AG(E)1125]. Potassium and 1,2-dimethoxyethane in THE in these conditions give a full dianionic sandwich 128. 

Gudat D (2003) Zwitterionic Phospholide Derivatives - New AmbiphUic Ligands. 232 ... 

Aromatic electrophilic acylations were described only in the coordination sphere of the phospholide anion involving phosphacymantrenes [43, 44] or phosphaferrocenes [45],... 

The reaction of Ba[P(SiMe3)2]2(THF)2 with diphenylbutadiyne in toluene for 12 days induces a m-addition of the diyne to the phosphide, followed by a 1,3-silyl group shift and ring closure. The dinuclear complex 132 is then isolated in good yield.283 Its complex structure contains Ba-C a bonds (2.881(5), 2.899(5) A), side-on Ba-alkyne (3.003(6), 3.363(6) A) and arene interactions, and Ba-phospholide bonds (Ba-P = 3.487(2) A) (Figure 65). 

The sodium atoms are both bound rf to one phospholide ring and 171 to the phosphorus atom of the other phospholide ring of the dianion. Each Na atom is further coordinated by one of the phosphole phosphorus atoms and two oxygen atoms of the DME coligand. The potassium complex is quite different reduction of the phosphole tetramer with 4 equiv of potassium yields a tetraanion, which, after crystallization from DME containing 18-crown-6, gives the solvent sepa-... 

The synthesis, chemistry, and complexing behavior of phospholide (6, with 6a, 6b, and 6c resonance structures) and polyphospholide anions have been reviewed recently.The [C H Ps J series with n = 0—4 is a complete set of structures with a successive replacement of CH units by the same heteroelement, P. The counterions are alkaline metals (e.g., Ps K+, which, together with K2HP7, has been obtained from red P in refluxing DMF in a yield of... 

Phospholide ions can form metal complexes with different coordination numbers / -complexation is characteristic for their aromatic behavior. The first 7 -complex with Mn(CO)3 (7) was reported in 1976. The ring in some cases (e.g., in 7) is not strictly planar. In 7, the P atom is displaced by 0.041 A from the plane of the carbon atoms. The large number of... 

Structural data of phospholide ions themselves are scarce. The lithium salt of the tetramethylphospho-lide ion, which is in fact an y -complex, and the K salt of the 2,4,5-tri-terf-butyl-l,3-diphospholide an-ion have been reported. Also the structure of the Li salt of the 2,5-bis(ferf-butyl)-l,3,4-triphospholide ion has been obtained In all these structures the bond lengths are equalized (CC, 1.396—1.424 A CP, 1.690-1.752 A). 

According to a semiempirical study by Malar, the different polyphospholide anions have 86—101% aromaticities of that of the cyclopentadienide anion. Chesnut and Quin reported on the basis of GIAO NMR calculations using a triple-valence quality basis set that the phospholide anion s aromaticity is 63% that of the cyclopentadienide anion. The aromatic stabilization energy (ASE) obtained by Schley-er et al. from eq 2 (X = P ) was 90% that of the cyclopentadienide anion. 

Keywords Aromatic phosphorus heterocycles Phospholides P ligands Zwitterions CT-Donor/ r-acceptor properties... 

Syntheses of Cationic and Neutral Phosphonio-Phospholide Derivatives. 178... 

Transformation Between Phosphonio-Phospholides by Modification of Substituents... 

Transformation of a phosphonio-substituted phospholide derivative under conservation of the r-electron system has been demonstrated in a number of cases which include substitution of a ring-hydrogen atom, replacement of a PRs -moiety by a hydride, or reductive de-arylation of a PhsP " - to a phosphinyl substituent PPh2. Subsequent re-quaternisation of the latter allows the formal substitution of a PhsP " - by a modified Ph2(R)P -moiety in a two-step reaction. The application of this scheme is not only perfectly suitable for the synthesis of bis-phosphonio-benzophospholides with different phosphonio-moieties but, since the last reaction stage tolerates a variety of functional groups in the electrophile, offers as well a convenient pathway for the synthesis of side-chain functionalised phosphonio-phospholide derivatives from more simple substituted precursors. 

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