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The countercation effect on the reactivity of ambiphilic o-(fluorodimethylsilyl)phenyl anion was investigated by replacing Li in 1 with Cu (4 and 5), Mg (6), and Zn (7). The reactivity of the aryl metal species was estimated by the yields of dimerized product 3, which were monitored by GC. X-ray crystallographic analysis, DFT calculations, and AIM analysis of bis(aryl)zinc 7 were performed. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:53–57, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.21062

A series of the monocyclic organophosphorus compounds ([o-OC(CH3)2C6H4]PPh(CH2 Ph)X) bearing a halogen (X = F, Cl, and Br) or a tetrafluoroborate (X = BF4) were synthesized. The solid-state structures of the bromide, the tetrafluoroborate, and an analogous fluoride ([o-OC(CF3)2C6H4]PPh(CH2 Ph)F) were determined by single crystal X-ray crystallography. The geometry of the fluoride was almost an ideal trigonal bipyramid (TBP). On the other hand, the bromide and tetrafluoroborate were essentially phosphonium salts with phosphorane character to some extent for the former. In CD3 CN, the bromide, the chloride, and the tetrafluoroborate were found to exist as phosphonium salts. However, it was suggested that in CDCl3, the bromide and the chloride have structures rapidly equilibrating or averaged between the phosphorane and the phosphonium forms. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:523–530, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20717

Reactions of o-(HSiR2)(BMes2)C6H4 (R = Me (3a), Ph (3b)) with a fluoride ion afford [o-(FSiR2)(HBMes2)C6H4]− (R = Me (5a), Ph (5b)), which involve the FSi⋅⋅⋅HB interaction to render the silicon atom pentacoordinate. The FSi⋅⋅⋅HB interaction in 5a was confirmed by X-ray crystallographic analysis and “atoms-in-molecules” (AIM) analysis. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:471–475, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20709

Neutral hexacoordinate organoantimony compounds LSb(Xyl)C6H4 (o-Y) [L = tridentate ligand; Xyl = C6H3 (3,5-Me2); Y = CH2 OMe (4), CH2 NMe2 (5), and 2-pyridyl (6)] with intramolecular coordination were synthesized. Single crystal X-ray crystallography revealed that the donor atom (N or O) of 4–6 was coordinated trans to one of the two carbon atoms of the tridentate ligand. Variable temperature (VT) NMR measurements of compounds 4 and 5 indicated that the stereomutations proceeded via dissociation of the Sb-donor (N or O) bond followed by SbC bond rotation. Compound 4 was found to have a stereomutation barrier of ca. 12 kcal mol−1. In the case of 5, dissociation of the SbN bond was found to be distinguishable from the stereomutation. Energies of SbN dissociation 5 and interconversion of enantiomers were estimated to be ca. 15 and ca. 19 kcal mol−1, respectively, from the VT-NMR measurements. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:553–561, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20721

Hypervalent bond (three center-four electron bond: 3c-4e) is the central feature of the structure and reactivity of hypervalent compounds. The SSS bond of thiathiophthene, the so-called no-bond resonance compound, is realized as one of the examples of 3c-4e bond centered at the sulfur atom (10-S-3). A variety of reactions such as cycloaddition-elimination, bond-switching rearrangement, and bond-switching equilibration of sulfur-containing heterocycles are exemplified to proceed through the presence of hypervalent 10-S-3 species. In the transition state of edge inversion, it is predicted that a vacant p-type orbital is perpendicular to the square planar species. Antimony(III) and bismuth(III) compounds bearing a bidentate Martin ligand and a phenyl, or 2-dimethylaminomethylphenyl, or 2,6-bis(dimethylaminomethyl)phenyl group were prepared. The rates of inversion of these compounds at the central atom of Sb or Bi were accelerated significantly by the coordination of the dimethylamino group and also of pyridine from the solvent, where 3c-4e bond is formed by the coordination to stabilize the transition state. Finally, the presence of rapid bond-switching equilibration between NB···N bond of 1,8-bis(dimethylamino)-9-(substituted)borylanthracenes was shown to proceed through 10-B-5 species at the transition state. It is concluded that the bond-switching equilibration takes place as a piston rod in the range of 1.32 A. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:161–175, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20326

By freezing Berry pseudorotation of spirophosphoranes with recourse to the rigidity of the Martin bidentate ligand, we successfully prepared configurationally stable enantiomeric pairs of optically active phosphoranes, and could isolate “anti-apicophilic” C-apical O-equatorial (O-cis) phosphoranes. The effect of σ*PO orbital of the O-cis phosphorane was investigated both experimentally and theoretically. O-cis phosphoranes were revealed to be much more electrophilic at the phosphorus atom than O-trans isomers by experimental studies. The acidity of the α-proton of an O-cis benzylphosphorane was found to be higher than that of the corresponding O-trans isomer. By the reaction of the α-carbanion of an O-cis benzylphosphorane with PhCHO, we succeeded in the first isolation and full structural characterization of a 12-P-6 phosphate bearing an oxaphosphetane ring, the intermediate in the Wittig type reaction using a 10-P-5 phosphorane. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:390–396, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10072

Hypervalent 10-Sn-5 allyl and crotyl tin ate complexes bearing Martin ligands were prepared and found to be surprisingly stable in water. These compounds were found to react with aldehydes in the presence of weak Lewis acids such as LiBr to give the corresponding homoallyl alcohols. Product analysis of the reaction of the crotyl compounds indicated that the reaction occurred via a cyclic transition state unlike an acyclic transition state operative for widely utilized allyltrialkyltin reagents that are of ordinary valency. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:425–430, 2001

[(Por)M(R)(OOR′)]+Y− (Por: TPP [tetraphenylporphyrin], OEP [octaethylporphyrin]; M: Sb, As, P; R: Me, Et, Ph; R′: H, C(=O)m-ClC6H4, t-Bu) were prepared from [(Por)M(R)(X)]+Y− (X: OTf, Br). The reactivities of the peroxide porphyrins toward nucleophiles such as triphenylphosphine increased in the order of -OOt-Bu, m-CPBA, and -OOH derivatives. Phosphorus (P-OOH) and arsenic hydroperoxide (As-OOH) were much more reactive than the corresponding antimony hydroperoxide (Sb-OOH). The higher reactivity of phosphorus and arsenic peroxides can be explained by the stability of the M=O (M=P, As) bonding system in the intermediates of the oxidation reactions. An X-ray structural analysis of [(TPP)Sb-(Me)(OOt-Bu)]+PF6− is presented. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:431–443, 2001

A stable hypervalent 10-Bi-4 species, tetraethylammonium bis[α,α-bis(trifluoromethyl)benzenemethanolato(2-)-C2],Obismuthanate(1-), was prepared by the reaction of bismuth trichloride with 2 equiv of lithium 2-(2-lithiophenyl)-2-propoxide derivatives. The ate complex was inert toward MeI, instead, the corresponding nonfluorinated analogue, bis[α,α-bis(dimethyl)benzenemethanolato(2-)-C2, O]bismuthanate(1-), was reactive enough toward MeI to give O-methylated product. Regioselective methylation at the nonfluorinated methanolate was observed in the reaction of unsymmetrically substituted ate complex, [α,α-bis(dimethyl)benzenemethanolato(2-)-C2, O[]α,α-bis(trifluoromethyl) benzenemethanolato(2-)-C2, O]bis-muthanate(1-). Mechanism of isomerization of these ate complexes and related protonated compounds and the synthesis and stability of [α,α-bis(trifluoromethyl)-benzenemethanolato (2-) -C2, O]diarylbismuthanate-(1-) were also described.