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Third Polymorph (third + polymorph)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Unmasking a Third Polymorph of a Benchmark Crystal-Structure-Prediction Compound,

ANGEWANDTE CHEMIE, Issue 45 2009
Saikat Roy Dr.
Auf der Jagd nach Polymorphen: Eine Form,III (N blau, S gelb, O rot) von 6-Amino-2-phenylsulfonylimino-1,2-dihydropyridin, einem für Blindtests in der Kristallstrukturvorhersage genutzten Molekül, wurde durch polymerinduzierte Heteronukleation erhalten. Die experimentellen Stabilitäten zeigen, dass die als thermodynamisch stabil berechnete Form,II in Wirklichkeit die am wenigsten stabile unter den drei Polymorphen ist. [source]

A new polymorph of dichloridotriphenylantimony

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2010
Daniel J. MacDonald
In a new polymorphic form of dichloridotriphenylantimony, [Sb(C6H5)3Cl2], there are two crystallographically unique molecules in the asymmetric unit and it has been determined that this polymorph is one of two kinetically favoured phases of pure dichloridotriphenylantimony, both of which have Z, > 1. A third polymorph, corresponding to (C6H5)3SbCl1.8F0.2, is also known and has Z, = 2. By contrast, the thermodynamically preferred polymorph of pure (C6H5)3SbCl2 has Z, = 1. A brief comparison of the known polymorphic forms of dichloridotriphenylantimony is presented. [source]

A third polymorph of 4-(2,6-difluorophenyl)-1,2,3,5-dithiadiazolyl

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2010
Elisabeth M. Fatila
The crystal structure of a third polymorphic form of the known 4-(2,6-difluorophenyl)-1,2,3,5-dithiadiazolyl radical, C7H3F2N2S2, is reported. This new polymorph represents a unique crystal-packing motif never before observed for 1,2,3,5-dithiadiazolyl (DTDA) radicals. In the two known polymorphic forms of the title compound, all of the molecules form cis -cofacial dimers, such that two molecules are ,-stacked with like atoms one on top of the other, a common arrangement for DTDA species. By contrast, the third polymorph, reported herein, contains two crystallographically unique molecules organized such that only 50% are dimerized, while the other 50% remain monomeric radicals. The dimerized molecules are arranged in the trans -antarafacial mode. This less common dimer motif for DTDA species is characterized by ,,, interactions between the S atoms [S...S = 3.208,(1),Å at 110,K], such that the two molecules of the dimer are related by a centre of inversion. The most remarkable aspect of this third polymorph is that the DTDA dimers are co-packed with monomers. The monomeric radicals are arranged in one-dimensional chains directed by close lateral intermolecular contacts between the two S atoms of one DTDA heterocycle and an N atom of a neighbouring coplanar DTDA heterocycle [S...N = 2.857,(2) and 3.147,(2),Å at 110,K]. [source]