Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/anie.201201566

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Trichloro[tris(3-tert-buty1-6-methoxyphenyl)methyl]- stannane (1), containing a tetradentate ligand with three methoxy groups as coordinating sites, was synthesized by the reaction of the corresponding (triarylmethyl)lithium species with tin tetrachloride. In contrast to the cases of the previously reported silicon and germanium analogues, 1 decomposed during column chromatography on silica gel and was slightly unstable against moisture. X-ray crystallographic analysis of 1 showed a heptacoordinate structure with interatomic distances between the oxygen atom and the central tin atom shorter than the sum of van der Waals radii.

DOI： 10.1021/om100386v

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER  

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. (C) 2010 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

DOI： 10.1016/j.crci.2010.06.010

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A fluorescent host molecule hearing a bicyclic triarylphosphate framework was synthesized. Its inclusion behavior to C-60 was revealed by fluorescent titration. Cocrystallization of the host and C-60 resulted in the formation of an inclusion complex in the crystalline state.

DOI： 10.1246/cl.2010.134

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

A ladder-type -conjugated molecule containing both thiaborin and carbazole units exhibited strong light absorption and emission like other ladder-type -conjugated molecules based on heteraborins.

DOI： 10.1080/10426501003769736

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

The intramolecular sila-Friedel-Crafts reaction was developed as a new method for the construction of a dibenzosilole skeleton. This reaction proceeds under mild conditions to afford the target in relatively good yield, indicating its availability as a versatile synthetic method. This reaction can be applied to the synthesis of pi-extended silole derivatives such as ladder-type silafluorene 8 and spiro-type silabifluorene 9. Furthermore, the synthesis of two-dimensionally extended silole derivatives utilizing the sila-Friedel-Crafts reaction as the multiple intramolecular cyclization was achieved, including the first synthesis of trisilasumanene 18. The X-ray crystallographic analysis of trisilasumanene 18 demonstrated the planarity in the main pi-framework, in contrast to sumanene and its sulfur analogue, trithiasumanene, bearing the bowl-shaped structures. In the UV-vis absorption spectra, the absorption bands of triphenylenosiloles 18 and 19 were slightly red-shifted compared to that of hexabutoxytriphenylene 22. The weak absorption bands were also observed in the longer-wavelength region in 18 and 19, which is derived from sigma*-pi* conjugation of the silole skeletons. In addition, 18 and 19 showed the blue fluorescence in dichloromethane and in the solid state.

DOI： 10.1039/c0dt00136h

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

A bis(dimesitylboryl)dibenzoazaborine formed Lewis acid-base type complexes with up to two cyanide ions in stepwise fashion. The complex formation constants for cyanide ion were larger than those for fluoride ion, despite the higher affinity of fluoride ion to boron atoms than that of cyanide ion. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jorganchem.2009.07.046

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

An intramolecular sila-Friedel-Crafts reaction was developed and applied to the synthesis of dibenzosilole derivatives. This reaction proceeds under mild conditions to afford the target in relatively high yield, indicating its availabilty as a versatile synthetic method. The synthesis of trisilasumanene, a silicon analogue of sumanene, was achieved using the present reaction.

DOI： 10.1021/ja906566r

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

pi-Conjugated dendrons and dendrimers based on dibenzoazaborine were synthesized. The azaborine dendrons exhibited strong light absorption and photoluminescence, reflecting the optical properties of the azaborine. The fluorescence from the azaborine dendrimers bearing a benzothiadiazole core was strongly red-shifted or quenched, indicating photoinduced electron transfer from the azaborine dendrons to the core unit.

DOI： 10.1021/ol901035d

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

A fluorescent chlorostannylene bearing a dipyrromethene ligand was synthesized. Its fluorescence quantum yield was low, Phi(f) = 0.04, probably because of the existence of the tone-pair orbital energetically close to the pi orbital, However, its fluorescence emission was increased to Phi(f) = 0.42 by dechlorination using silver triflate. The resulting cationic species reverted again to the chlorostannylene upon reaction with tetrabutylammonium chloride, with a corresponding weakening of the fluorescence.

DOI： 10.1021/ja904470m

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Language：Japanese   Publisher：SOC SYNTHETIC ORGANIC CHEM JPN  

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.

DOI： 10.5059/yukigoseikyokaishi.67.787

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

New cationic triarylboranes bearing ammonio or phosphonio groups on the periphery were synthesized from a common intermediate, a dibromodibenzoazaborine. These cationic molecules are soluble in highly polar organic solvents as well as water, and they exhibit strong light absorption and photoluminescence emission in water. Complexation of the cationic azaborines with fluoride and cyanide ions in aqueous media proceeded and could be monitored by NMR, UV/Vis, and fluorescence spectroscopy.

DOI： 10.1002/chem.200802159

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

An azaborine bearing two dimesitylboryl groups on its periphery showed very strong light absorption and moderate photoluminescence emission; the reaction of the title compound with fluoride ion resulted in multi-step fluoride ion complexation on the boron atoms of the dimesitylboryl groups, producing mono- and bisfluoroborates.

DOI： 10.1039/b818505k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Novel hetero-pi-conjugated compounds (dibenzochalcogenaborins) with the same molecular framework, bearing a boron atom as an acceptor and chalcogen atoms as a donor, were synthesized, and systematic comparisons among these molecules were performed. X-ray crystallographic analysis of these molecules showed similar structures with high planarity. UV/Vis spectroscopy and theoretical calculations revealed that the absorption maxima and the HOMO-LUMO gap changed by systematically changing the bridging chalcogen atom. Dibenzooxaborin and dibenzothiaborin showed fluorescence emission both in solution and in the solid state with a small Stokes shift, indicating the high rigidity of these compounds. On the other hand, dibenzoselenaborin exhibited a very weak fluorescence as a result of the heavy atom effect.

DOI： 10.1002/asia.200800302

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

1-Alkyl- and 1-aryl-5-carbaphosphatranes were prepared by the reaction of 1-hydro-5-carbaphosphatrane with nucleophiles and subsequent intramolecular oxidative cyclization. X-ray crystallographic investigation of the t-butyl derivative revealed that it has a perfectly anti-apicophilic arrangement. The apical 1JPC coupling constants of the 5-carbaphosphatranes were extraordinarily large.

DOI： 10.1080/10426500902748080

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

A triarylmethane-based host molecule with three anthryl groups that can interact with C-60 was synthesized. Co-recrystallization of this host molecule with C-60 resulted in a linear alignment of C-60 in the hexagonal columnar space formed by intra-and intermolecular CH center dot center dot center dot pi interactions between anthryl groups in the crystalline state.

DOI： 10.1039/b909881j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

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.

DOI： 10.1080/10426500701735296

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Rh complexes 5 and 6 were synthesized via the titled carbine 1. In the IR spectrum of 6, the carbonyl stretching frequency was observed at the lower wave number among all [(carbene)Rh(CO)(2)Cl] complxes reported to date, including the highest electron-donating ability of carbene 1.

DOI： 10.1080/10426500701795167

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

A novel N-heterocyclic carbene, amino(sulfur-ylide)carbene, which is stabilized by electron donation from the carbanion of a sulfur ylide as well as a nitrogen atom, was generated and its Rh complex was synthesized; the electron donating properties of the amino(sulfur-ylide) carbene were investigated using the IR carbonyl stretching frequencies of the Rh complex, indicating a relatively strong electron-donating ability among reported carbenes.

DOI： 10.1039/b813454e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

DOI： 10.1002/anie.200704746

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Treatment of tripodal tris(3-tett-butyl-2-hydroxy-5-methylbenzyl)amine (L) with 1 equiv of trimethylaluminum in toluene gave the stable proalumatrane (AIL) (1) [wherein L = tris(3-tert-butyl-5-methyl-2-oxidobenzyl)amine] featuring a distorted trigonal monopyramidal four-coordinate aluminum geometry. An analogous reaction uses the less sterically congested isomer of L, namely, tris(5-tert-butyl-2-hydroxy-3-methylbenzyl)amine provided dimeric (AIL')2 (2) [wherein L' = tris(5-tert-butyl-3-methyl-2-oxidobenzyl)amine], which contains two bridging alumatrane moieties possessing five-coordinate TBP aluminum geometries. Reaction of AIL with water provided the adduct H2O center dot AIL (3), a species that is representative of a coordinatively stabilized intermediate in the hydrolysis of an aluminum alkoxide. Theoretical calculations revealed that considerable stabilization energy is obtained by the coordination of a water molecule to the tetracoordinate aluminum in AIL and that this result is consistent with the postulate that the Lewis acidity of AIL exceeds that of boron trifluoride, despite the presence of the transannular N -> Al bond in AIL.

DOI： 10.1021/ic7010327

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Two cationic triarylboranes based on phosphomoborin frameworks have been investigated. Electron-withdrawing phosphonio groups enhanced the Lewis acidity of these boranes which capture fluoride ion in aqueous media and transport it into organic phase.

DOI： 10.1246/cl.2007.976

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Azaborines and ladder- type azaborines bearing various functional groups can be synthesized starting from common dibromo derivative intermediates, and among several substituents, the carbazol- 9- yl group was shown to enhance the photo- luminescence quantum yield of the azaborines up to a value of unity.

DOI： 10.1039/b706418g

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Language：English   Publisher：WILEY-V C H VERLAG GMBH  

Ladder-type pi-conjugated molecules bearing heteraborin (azaborine or thiaborin) units were synthesized, and X-ray crystallographic analysis of pentacene-type molecules showed that these molecules have rigid and planar structures. UV-visible spectroscopy and theoretical calculations revealed the enhancement of electronic interaction between heteraborin units, the decrease in HOMO-LUMO energy gaps, and the strong effect of the bridging main-group elements (nitrogen or sulfur) on the electronic states. The ladder-type molecules emitted strong fluorescence both in solution and in the solid state, and the emission-band shapes were different from each other, indicating the existence of intermolecular interactions in the solid state. Complex formation of the ladder molecules with fluoride ion was monitored by UV-visible spectroscopy, which revealed that the Lewis acidity of these molecules can be controlled by the elongation of it systems and the change of the bridging main-group elements.

DOI： 10.1002/chem.200700622

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The phosphonium borane [p-Mes(2)B(C6H4)PMePh2](+) complexes fluoride in water containing 10% methanol with a binding constant of 1.0(+/- 0.1) x 10(3) M-1 to afford the zwitterion p- Mes(2)FB(C6H4) PMePh2.

DOI： 10.1039/b616814k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Dibenzophosphaborin 1 and dibenzoazaborine 7 have been synthesized from the corresponding dibromides and MesB(OMe)(2). Dibenzophosphaborin P-sulfide 2, the P-selenide 3, and the phosphonium salt 4 were obtained by the reaction of 1 with S-8, elemental selenium, and benzyl bromide, respectively. Crystallographic analysis of 1-3 and 7 showed that the dibenzophosphaborin framework does not have a planar structure, which is caused by the pyramidalization around the phosphorus atoms, unlike in 7. Compound 1 showed a blue-shifted and weak UV-vis absorption relative to 7, indicating a weak electronic interaction between the phosphorus lone pair electrons and the pi-orbitals on the dibenzopnictogenaborin framework. The longest absorption bands of 2 and 3 are attributable to the intramolecular electron transfer from the lone pair electrons on the chalcogen atoms to the pi* orbitals on the dibenzophosphaborin framework, and the existence of these electronic transitions is supported by TD-DFT calculations. The UV-vis and B-11 NMR spectra of 4 showed a temperature-dependent change due to the coordination of a counter bromide anion to the boron center, indicating a strong Lewis acidity of the boron center. We also investigated the complex formation ability of dibenzopnictogenaborin to fluoride or chloride anions. The complex formation constants increased in accordance with the decrease in LUMO energy levels calculated using the DFT method. Compound 4 exhibited an anomalously high complex formation ability among these compounds, due to the strong electron-withdrawing effect of the phosphonium cation moiety.

DOI： 10.1021/ic061055q

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Trichloro[ tris(3-tert-butyl-6-methoxyphenyl) methyl] germane ( 3), containing a tetradentate ligand with three methoxy groups as coordinating sites, was synthesized by the reaction of the corresponding (triarylmethyl) lithium species with tetrachlorogermane. In contrast to the case for the previously reported trichlorosilane analogue, 3 slowly decomposed during column chromatography on silica gel, although it was quite stable against moisture. The corresponding trifluoro-, tribromo-, and triiodogermanes 4-6 were prepared from the trichlorogermane 3. X-ray crystallographic analyses of 3-6 showed heptacoordinate structures with interatomic distances between the oxygen atom and the central germanium atom shorter than the sum of van der Waals radii. By systematic comparisons of these intramolecular interactions based on the interatomic distances, it was found that they strongly depend on the Lewis acidity of the trihalogenated germanium atom. An Atoms-in-Molecules (AIM) analysis of the model compound 4', in which three tert-butyl groups of trifluorogermane 4 were omitted, showed the existence of weak and ionic bonding between oxygen and germanium atoms. Reactions of these trihalogermanes with aqueous NaOH, LiAlH4, and BX3 were also investigated. Alkaline hydrolysis of trihalogermanes resulted in the cleavage of the carbon-germanium bond. LiAlH4 also caused the same kind of bond cleavage, together with nucleophilic attack on the germanium atom, giving the trihydrogermane 8. Reaction of the trihalogermanes with trihaloboranes was found to be an efficient procedure to give other trihalogermanes through a halogen exchange reaction.

DOI： 10.1021/om060031o

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Ladder-type fused azaborines were synthesized. X-ray crystallographic analysis of a pentacene-type molecule shown here revealed the planarity of a fused azaborine. It was revealed by UV-vis and fluorescence spectra that such fused molecular structures are efficient for the extension of pi-conjugated systems containing main group elements.

DOI： 10.1021/ol060539n

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The reaction behavior of 1-hydro-5-carbaphosphatrane (1a) was examined. Treatment of la with oxidants such as 3-chloroperoxybenzoic acid (mCPBA) and tBuOCl gave cyclic phosphonate 2 and 1-chloro-5-carbaphosphatrane (4), respectively, via cyclic phosphonite 3, a tautomer of la. Compound 4 was readily hydrolyzed to afford 2. Compound la was also sulfurized via 3 by elemental sulfur to afford cyclic thioxophosphonate 5. which was also obtained by reactions in the presence of bases. Treatment of la with bases also proceeded through 3 to give an equilibrium mixture of the corresponding phenoxide anion 10 and the phosphoranide anion 9, which was quenched with MeI to afford a mixture of 11 and 1-methyl-5-carbaphosphatrane (1b). Such reactivities are typical for neutral phosphoranes. Theoretical investigations of these reactivities were also performed.

DOI： 10.1002/chem.200500864

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The low sigma-donating ability of 9-phosphatriptycene 1 was revealed by cyclic voltammetry and theoretical calculations. The tungsten complex of 1 was synthesized and the IR and NMR spectroscopic data of the complex also suggested the low sigma-donating ability of 1. 1 was shown to be effective as a ligand in the palladium-catalyzed reactions, the Stille coupling and the Heck reaction.

DOI： 10.1246/cl.2004.1028

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A novel synthetic route to a 9-phosphatriptycene was developed by utilizing ortho-lithiation of a triarylphosphine oxide as a key step. Systematic comparisons of the NMR spectra of 9-phosphatriptycene derivatives indicated the large s character of the lone pair orbital or the phosphorus-chalcogen bonds of the 9-phosphatriptycene derivatives.

DOI： 10.1246/cl.2003.1144

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

DOI： 10.1080/10426500290094323

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

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.

DOI： 10.1080/10426500290092677

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

1-Hydro-5-carbaphosphatrane (1) and 1-methyl-5-carbaphosphatrane (2), the first 5-carbon analogues of phosphatranes, were synthesized by a demethylation reaction of cyclic phosphinate 3, X-ray analysis revealed that 1 has a typical trigonal bipyramidal structure with hydrogen and carbon atoms at the apical position and three oxygen atoms at the equatorial positions, indicating that 1 is a phosphorane in the perfectly "anti-apicophilic" arrangement. Apical P-C and P-H bond lengths were 1.921(2) and 1.38(2) Angstrom, respectively. The (1)J(PH) value of 1 and the (1)J(PC)(P-CH(3)) value of 2 were 852 and 215 Hz, respectively, which are extraordinarily large for the apical coupling constants of phosphoranes, but close to those of the reported phosphatranes with a 5-nitrogen atom. IR and Raman spectra are also reported. Force constant calculations indicate the transannular bond in carbaphosphatrane is 3 times stronger than in silatrane, due to its covalent character.

DOI： 10.1021/ja011458j

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

DOI： 10.1021/ja0056264

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GORDON BREACH PUBLISHING, TAYLOR & FRANCIS GROUP  

1-Hydro-5-carbaphosphatrane 4, the first 5-carbon analog of a phosphatrane, was synthesized. X-ray crystallographic analysis showed that it has a typical TBP structure and that it is a 10-P-5 phosphorane in a perfectly "anti-apicophilic" arrangement.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

1-Hydro-5-carbaphosphatrane 4, the first 5-carbon analog of a phosphatrane, was synthesized. X-ray crystallographic analysis showed that it has a typical TBP structure and that it is a 10-P-5 phosphorane in a perfectly "anti-apicophilic" arrangement.

DOI： 10.1080/10426500108546641

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The reaction between BmtLi (Bmt = 4-tert-butyl-2,6-bis[(2,2 ",6,6 "-tetramethyl-m-terphenyl-2'-yl)-methyl]phenyl) and AlH3NMe3 in DME gave a stable organotrihydroaluminate, BmtAlH(3)Li(DME)(2) (6), whose monomeric structure was established by X-ray analysis. Compound 6 showed high reactivity as a reducing agent toward unsaturated compounds such as benzophenone, phenyl benzoate, and benzonitrile.

DOI： 10.1021/om9805032

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

A thionitrosoarene generated by the desulfurization reaction of a stable N-thiosulfinylaniline bearing a bowl-type substituent underwent the intramolecular cyclization reaction involving the ortho-alkyl group to afford the corresponding 3,3a-dihydro-2, 1-benzisothiazole, The intermediacy of the thionitrosoarene was corroborated by a trapping experiment with aniline.

DOI： 10.1246/cl.1998.981

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