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Abstract: Since the synthesis of the first pentacoordinated organophosphorus compound, Ph5P, by Wittig, the chemistry of pentacoordinated phosphorus compounds has been extensively expanded. Pentacoordinated phosphorus compounds usually take a trigonal bipyramidal structure with two distinctive sites; apical and equatorial positions. In the trigonal bipyramidal structure, electronegative and small substituents prefer the apical positions. Such properties are widely recognized as the apicophilicity rule. However, several examples breaking the apicophilicity rule have been reported in the past few decades and novel properties and reactivities of these new classes of compounds have been found. In this review, the synthesis of novel pentacoordinated phosphoranes with anti-apicophilic arrangement will be introduced, as well as their structures, spectroscopic properties, and reactivities. [Copyright &y& Elsevier]

A 5-carbaphosphatrane and a 6-carbaphosphatrane were synthesized by utilizing triarylmethyl-type tetradentate ligands. Their structures were determined by X-ray crystallographic analysis to reveal that they have nealy ideal trigonal bipyramidal structures with a perfectly anti-apicophilic arrangement. 1JPH and 1JPC values of carbaphosphatranes were shown to be extraordinarily large as an apical coupling constant. The reactivities of carbaphosphatranes based on the tautomerization with their corresponding phosphonites were demonstrated in some reactions. [ABSTRACT FROM AUTHOR]

Dibenzo-1,4-phosphaborins were synthesized and characterized by X-ray crystallographic analysis. The phosphaborins exhibited UV/vis absorption derived from intramolecular charge transfer from the phosphorus atom to the boron atom. The phosphaborins showed different fluorescent properties depending on the substituents on the phosphorus atom. The phosphaborin was easily derivatized to P-sulfide, P-selenide and phosphonium salt. The phosphaborin and its P-derivatives formed complexes with fluoride ion. The complex formation constants were shown to increase in accordance with the decrease in their LUMO energy levels. [ABSTRACT FROM AUTHOR]

A phosphoniafluorene and a spirobiphosphoniafluorene bearing 4-(diethylamino)styryl groups were synthesized. These compounds exhibited bathochromically shifted absorption and emission, compared with their silicon analogues, because of the strong acceptor property of the phosphonium core. They also showed enhanced two-photon absorptions at around 930 nm. [ABSTRACT FROM AUTHOR]

Oxidation, sulfurization, and selenation of a 1-hydro-5-carbaphosphatrane afforded the corresponding cyclic phosphonate, cyclic phosphonothioate, and cyclic phosphonoselenoate, respectively. These results indicate the existence of the tautomerization between the five-coordinate 5-carbaphosphatrane and the three-coordinate cyclic phosphonite. [ABSTRACT FROM AUTHOR]

The reaction of a phosphorus ylide with elemental sulfur gave a pentacoordinate thiaphosphirane, which was characterized by X-ray crystallographic analysis, and it was allowed to react with elemental sulfur resulting in a thiophosphinate. [ABSTRACT FROM AUTHOR]

Analyzes the synthesis and chemical structure of phosphatriptycene oxide. Lithiation of tris(3-methoxyphenyl)phosphine oxide with t-BuLi; Findings of the x-ray crystallographic analysis of phosphatriptycene oxide.

Reports on a study which dealt with the synthesis and structure of novel nano-scale triarylphosphines with a dendrimer-type framework. Methodology in the preparation of phosphine; Application of X-ray crystallographic analysis to establish phosphine structure; Preparation of phosphine bearing isopropyl groups.

Hydrazobenzenes 3–5 bearing a chalcogenophosphoryl group were synthesized by palladium-catalyzed cross-coupling reactions. Their X-ray crystallographic analyses and NMR and IR spectra showed the presence of intramolecular hydrogen bonds between the N-H protons and the chalcogenophosphoryl groups. The intermolecular hydrogen bonds in phosphine oxide 3 and selenide 5 were observed in the solid state. Phosphine oxide 3, sulfide 4, and selenide 5 constructed a dimeric structure, a discrete monomeric structure, and a chain structure, respectively. As the chalcogen atom changed, the crystalline structures of the 2-chalcogenophosphorylhydrazobenzenes also changed. The hydrogen bonds affected the oxidation reactions of the hydrazobenzenes, and oxidation of hydrazobenzenes bearing a lighter chalcogen atom was more difficult. For azobenzenes bearing a chalcogenophosphoryl group, X-ray crystallographic analyses and NMR spectra showed little interaction between the azo group and the chalcogenophosphoryl groups. However, in the UV-vis spectra, the red shifts of the absorption maxima due to the n → π+ transitions indicated intramolecular interactions in the excited state, in contrast to the corresponding 4-substituted azobenzenes. In addition, photoirradiation of phosphine oxide (E)-7 gave (2)-7, whereas that of phosphine sulfide (E)-8 and phosphine selenide (E)-9 did not give (Z)-8 and (2)-9, suggesting that heavy chalcogen atoms quench excited states by through-space interactions. Introduction of a chalcogenophosphoryl group at the 2-position had a significant effect on the structure, spectral properties, and reactivity of hydrazobenzenes and azobenzenes. Although azobenzene (E)-10 bearing a hydroxyphosphoryl group at the 2-position did not show hydrogen bonding in the crystalline state, its optical properties and photoisomerization ratio were different from those of (E)-7. [ABSTRACT FROM AUTHOR]

The article focuses on thermal and photocontrol of the equilibrium between a 2-phosphinoazobenzene and an inner phosphonium salt. Tertiary phosphines usually serve as soft bases and play an important role in catalytic reactions as ligands for transition metals. Quaternary phosphonium salts are involved as intermediates in many reactions, such as the Arbuzov reaction, the Mitsunobu reaction, and reactions with the Appel reagent. Many phosphonium salts have been synthesized by a nucleophilic attack of tertiary phosphines on electrophiles, such as alkyl halides and activated double bonds.

Examines the synthesis of selenaphosphirane involving a pentacoordinate phosphorus atom. Stabilizing effect of the Martin ligand; Molecular structure in solid and solution state; Chemical bonds.

Abstract: Novel bowl-shaped triarylphosphines, tris(2,2″,6,6″-tetraalkyl[1,1′:3′,1″-terphenyl]-5′-yl)phosphines (TRMP: alkyl=methyl; TRIP: alkyl=isopropyl), were prepared by lithiation of the corresponding m-terphenyl bromides followed by reaction with PCl3. X-ray crystallographic analysis revealed that the phosphorus center of TRMP is embedded in the shallow bowl-shaped cavity of 16 Å diameter and 2.1 Å depth formed by three radially extended m-terphenyl units. Its cone angle was estimated to be as large as 174°. In the crystal structure of TRIP, the depth of the cavity and cone angle increased to 3.3 Å and 206°, respectively, because of the different arrangement of the m-terphenyl units. In contrast with TRMP, which can form the mononuclear complex, PdCl2(TRMP)2 (6), in the reaction with PdCl2, treatment of TRIP (1 or 3 eq.) with PdCl2 produced the trinuclear palladium(II) chloride complex, [(PdCl2)3(TRIP)2] (8), as a single product. X-ray crystallography established the structure of 8, where the trimer of PdCl2 is terminated by two TRIP ligands. The formation of the different types of PdCl2 complexes was explained in terms of the difference in the cavity shape of TRMP and TRIP. [Copyright &y& Elsevier]