Isolation, absolute configuration, and chiral crystallization of optically active seleninic acid

Zero-, one-, two- and three-dimensional supramolecular architectures sustained by Se…O chalcogen bonding: A crystallographic survey

“…16 j, sustained by either Se … O(carbonyl), 176 and 177 , or Se … O(methoxy), 178 , interactions. A helical chain, also with 2 1 screw symmetry, occurs in the crystal of 179 [216] , Fig. 16 k, as the selenium atom accepts bond Se … O(oxide) and Se … O(hydroxyl) interactions, rather than the single Se … O interactions of the previous three examples.…”

“…The chemical diagrams for these species, i.e. 160 – 180 [93] , [104] , [105] , [113] , [188] , [206] , [207] , [208] , [209] , [210] , [211] , [212] , [213] , [214] , [215] , [216] , [217] , are shown in Fig. 15 .…”

Racemic compound against racemic conglomerate formation: The crystal properties of allylbenzylmethylphenylphosphonium iodide as compared with the nitrogen analogue

“…The organic compounds mentioned may be made of methanesulfinic and methaneseleninic acids MeE(O)OH, E 5 S, Se. 8,9 The similar isomorphism would be expected from phosphonium salts by analogy with the corresponding ammonium salts.…”

“…For this reason both the compounds crystallize in the same homochiral mode, space group P2 1 2 1 2 1 , with the close unit cell parameters (a 5 7.832, b 5 8.234, c 5 5.360 Å for sulfur, and a 5 7.709, b 5 8.117, c 5 5.465 Å for selenium analogue). 8,9 It seems likely that for a molecule bearing mobile substituents, the change of the chemical nature of the chiral center inevitably accompanied by restriction/liberation of some of the conformational degrees of freedom will lead to substantial changes in crystallization features. The investigated case of ammonium/phosphonium interrelation is an example of how this effect manifests itself.…”

The crystal structure of benzeneseleninic acid anhydride, C12H10O3Se2

“…To prevent accidental isolation of the anhydride of benzeneseleninic acid (that was used as a precursor to generate the catalytically-active benzeneseleninic acid in situ) it was subjected to a diffraction study. The molecular and crystal structures of methylseleninic acid [15] and benzeneseleninic acid [16] have been reported in the literature. Only one report about the structure of a seleninic acid anhydride has appeared in print so far [17].…”