Crystal Structures Of Salts Research Articles

Chiral discrimination upon crystallisation of the diastereomeric salts of 1-arylethylamines with mandelic acid or p-methoxymandelic acid: interpretation of the resolution efficiencies on the basis of the crystal structures

The crystal structures of the diastereomeric salts of 1-arylethylamines with mandelic acid or p-methoxymandelic acid have been studied. This revealed that there was correlation between the efficiencies of the optical resolutions of the amines with the resolving reagents and the crystal structures of the salts. A characteristic hydrogen-bond layer, consisting of stable columnar structures and having a planar boundary surface, was found to be common to the less-soluble salt crystals; these crystals were considered to be stabilised from the viewpoint of both their hydrogen-bonding and van der Waals interactions. In contrast, in the corresponding more-soluble salts and in those diastereomeric salts which could not be separated by crystallisation, no such particularly stabilised crystal structure was formed; there only existed either columnar structures or planar boundary surfaces in these crystals. These results strongly suggest that for successful resolution it is necessary to realise a hydrogen-bond layer, consisting of stable columns and having planar boundary surfaces, in the crystals of one of the pair of diastereomeric salts. In order to achieve such a crystal structure, complementarily in molecular length between a target racemate and a resolving reagent must be considered the most important and fundamental factor.

The first X-ray crystal structure of an O-alkyl aminosulfoxonium salt: conclusive evidence for O-alkylation of sulfinamides and planarity of nitrogen

The X-ray crystal structure of O-methyl (2R,5R)-bis(methoxymethyl)pyrrolidin-1-yl-(S)-p-tolylaminosulfoxonium tetraphenylborate 5 is reported: this is the first X-ray crystal structure of an O-alkyl aminosulfoxonium salt, and provides conclusive evidence that alkylation of sulfinamides occurs on oxygen.

Crystal Structure and Magnetic Properties of an Organic Ion-Radical Salt: 1,3'-Diethyl-2,2'-Quinoselenacyanine-[TCNQ]2

The crystal structure and magnetic properties of an organic ion-radical salt, 1,3'-diethyl-2,2'-quinoselenacyanine-[TCNQ] 2 , are reported. The salt forms triclinic crystal in the space group \(P\overline{1}\) with a =14.180(3), b =17.689(2), c =8.244(1)A, α=103.13(1), β=93.14(1), γ=70.06(1)° and Z =2. The spin-susceptibility of the salt shows two broad maxima near 45 and 195 K. A single ESR absorption line is observed for single crystals above 40 K and its linewidth strongly depends on the temperature and external magnetic field direction. On the contrary, two side lines due to an excited triplet state are observed below 40 K with a central line. These experimental results are discussed on the basis of the peculiar crystal structure of the salt.

Stable homopolyatomic anions. Synthesis and crystal structures of salts containing the pentaplumbide(2-) and pentastannide(2-) anions

The synthesis and crystal structure are reported for two salts in which the pentaplumbide(2--) (I) and pentastannide(2--) (II) anions have been stabilized as a result of complexation of the sodium cations by 4, 7, 13, 16, 21, 24-hexaoxa-1, 10-diazobicyclo(8.8.8)hexacosane (2,2,2-crypt). The phases are prepared by the reaction of solutions of crypt in ethylenediamine with the intermetallic compositions NaPb/sub 1.7-2/ and NaSn/sub 1--1.7/. The compounds are trigonal and isostructural; for I a = 11.615 (3) A and c = 22.120 (12) A while for II a = 11.620 (1) A and c = 22.160 (7) A, the data applying at temperatures of approximately 5 and approximately 30/sup 0/C, respectively. The compounds contain the trigonal-bipyramidal homopolyatomic anions Pb/sub 5//sup 2-/(I) and Sn/sub 5//sup 2--/ (II) with substantially D/sub 3h/ symmetry. In Pb/sub 5//sup 2--/ the equatorial-equatorial and axial-equatorial bond distances are 3.238 (4) and 3.002 (3) A, respectively, while in Sn/sub 5//sup 2--/ the corresponding distances are 3.095 (10) and 2.887 (7) plus 2.854 (6) A. crypt complexation of sodium or potassium cations is evidently not sufficient to allow isolation of these derivatives of the Pb/sub 9//sup 4--/ anion from ethylenediamine or ammonia solvents.