Phosphabenzene Complexes

Phosphabenzene Complexes.—Photolysis of [CpMn(CO)2(L)j (L=P-bonded 2,4,6-triphenyl- and 2-phenyl-4,5-dimethyl-phosphabenzene) affords the sandwich complexes [CpMn( -L)]. ... 

A structural study of a molybdenum carbonyl complex of phosphabenzene has shown that the phosphorus is a-bonded to the... 

Complexes with diphosphenes, phosphabenzene, biphosphinine, and other unsaturated phosphorus donor ligands... 

The orange, air-stable, homoleptic tetrakis( 71-phosphabenzene)nickel (1046) is tetrahedral (point symmetry 54) and can be obtained from phosphabenzene and [Ni(cod)2].2 25 It features a short Ni—P bond length of 2.1274(5) A with considerable N i P 7r-backbonding and a i/(Ni—P) stretch at 168 cm-1. In solution, partial dissociation of one phosphabenzene ligand is observed. 2-Diphenylphosphino-3-methylphosphinine forms with [Ni(cod)2] in the presence of the CO the dinuclear complex (1047) with a W-frame structure.2526... 

Phosphaalkynes, in platinum complexes, 8, 645 Phosphaazallenes, with platinum, 8, 633 Phosphabenzenes, with chromium, 5, 339 Phosphaboranes... 

A benzannulation was carried out with 42 and carbene complex 41 to give phosphaphe-nanthrene 43 in high yield (Scheme 19), whereas yields of phosphabenzenes were only marginal [52]. 

The metal vapor ligand codeposition method has extended the array of such sandwich complexes. A wide range of substituents can be tolerated on the arene ring unusual arene M complexes have been prepared. Elschenbroichmade the interesting compound bis(j7 -phosphabenzene)vanadium, which is less air sensitive than the ligand itself. It turned out that the phosphorus heteroatom has a much stronger influence on the electron affinity of the free arene than of the bound arene. 

Recent efforts in regard to phosphabenzene derivatives have particularly been concerned with metal complexes and theoretical considerations. These areas have been reviewed recently. ... 

Some work has been performed with bis (arene) vanadium and bis (heteroarene) vanadium complexes [7-10]. As indicated for the selected complexes shown in Table 1, replacement of benzene by phosphabenzene and arsabenzene lowers the reduction potential. This counterintuitive result has been explained in terms of a greater positive charge on the metal... 

Fig- 15.42 Complexes of phosphabenzene. borabenzene. borazine. and arsabenzene. These six-membered rings are analogous 10 benzene, i.c.. they are six-eleciron donors and are aromatic. 

The reactions of the phosphabenzene system [124] confirm these conclusions. Phosphabenzenes have low basicity towards hard acids. They are not protonated by CF3CO2H nor alkylated by trialkyloxonium salts. However, soft acids attack at phosphorus. For instance, 2,4,6-triphenyl-phosphabenzene forms compounds 4 with the hexacarbonyl derivatives of Cr, W and Mo in which the phosphorus coordinates to the metal, possibly with metal-P back-donation. The complexes 4 rearrange photochemically or thermally affording the 67i-heteroarene complexes 5. Although 2,4,6-triphenyl-pyridine is protonated on nitrogen, it undergoes complex formation with chromium hexacarbonyl exclusively on the phenyl moieties yielding the ri -arene complexes 6 [125]. 

Hg NMR, 4 Phlorins, 855 Phosphabenzene transition metal complexes, 1041 Phosphacymantrenes transition metal complexes, 1043 Phosphaferrocenes transition metal complexes, 1043 Phosphates dialkyldithio metal complexes, 643 diaryldithio metal complexes, 643 trialkyldithio metal complexes, 642 trialkylthio... 

Phosphabenzenes fail to react with hard acids, yet they readily form o complexes with soft metal compounds (142). The alkylation of 1,2,4,6-tetra-phenylphosphabenzene anion takes place at P, while acylation occurs at the harder C-4 (143). 

Ashe Sutherland Braye Woodward and Eschenmoser Ginsberg and Lindsell Franz Synthesis of phosphabenzene (phosphinine) C3H3P Importance of c-AMP established Phospholide anion characterised Synthesis of vitamin B12 Synthesis of first P4 complex with an M-P bond Development of the herbicide Glyphosate... 

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