Hiroshi Yoshioka

X-ray and IR studies on crystal and molecular structure of 4-nitro-2,6-diphenylphenol. Stereochemistry of bifurcated OH⋯π hydrogen bonds

Abstract The crystals of the title compound contain both intra- and inter-molecular OH⋯π hydrogen bonds (the first example of bifurcated OH⋯π bonds), the stereochemistry of which has been elucidated by an X-ray structure analysis; this bifurcated bond is also supported by the observation based on the IR spectrum of the crystals.

Periandrin I, a sweet triterpene-glycoside from periandra dulcis

Abstract Further investigation of the natural sweeteners of Periandra dulcis afforded a new sweet triterpene-glycoside, periandrin I, the structure of which was determined to be 3-,β-O-[β- D -glucuronopyranosyl-(1→2)-β- D -glucuronopyranosyl]-25-al-olean-18(19)-en-30-oic acid by chemical and physicochemical evidence and also by X-ray crystallographic analysis of a derivative.

Structures of two alkaline autoxidation products of BHA, a widely used antioxidant

In order to confirm the structures of the autoxidation products of 2-tert-butyl-4-methoxyphenol (BHA), X-ray crystallographic analyses have been undertaken. One of the products was converted to a dibenzoate, which was subjected to the analysis to establish the structure as the O6,O7-dibenzoyl derivative of (1R*,2R*,6S*,7S*,9R*)-4,9-di-tert-butyl-6,7-dihydroxytricyclo[5.2.2.02, 6]undec-4-ene-3,8,10-trione. Crystallographic analysis of the major isomer of the two isomeric products gave its structure as (E)-4-tert-butyl-2-(3-tert-butyl-4-oxocyclopent-2-en-1-ylidene)cyclopent-4-ene-1,3-dione, which also established the structure of the minor isomer as the corresponding (Z)-isomer.

Preparation and properties of tetrathiafulvalene (ttf) and tetramethyltetraselenafulvalene salts of tin(IV) halide anions and X-ray crystal structure of [ttf]3[SnCl6]

Tetrathiafulvalene (ttf) reacts with SnX4(X = Cl or Br) in MeCN to give [ttf]2[SnX6]. The corresponding tetramethyltetraselenafulvalene (tmtsf) salt also is obtained as an acetonitrile solvate, [tmtsf]2[SnCl6]·MeCN, by the reaction of tmtsf with SnCl4 in MeCN. On the other hand, electrocrystallization of ttf and tmtsf in the presence of SnX62–(X = Cl or Br) or [SnMe2Cl3]– in MeCN or in CHCl2CH2Cl affords [ttf]3[SnX6], [ttf]3[SnMe2Cl4], or [tmtsf][SnMe2Cl3]. Electrical resistivities of these salts as compacted samples fall in the range 1.6 × 101–9.9 × 104Ω cm at 25 °C. The stacking of the ttf and tmtsf moieties is discussed on the basis of electronic reflectance spectra. A single-crystal X-ray analysis of the salt [ttf]3[SnCl6] has revealed a layer structure consisting of ttf trimers. The tetragonal crystal, space group P4/mbm, has cell dimensions a= 11.807(1), c= 11.861(2)A;, and Z= 2. Block-diagonal least-squares refinement, based on 876 independent reflections with |Fo| > 3σ(F), yielded an R factor of 0.040.