Szupramolekuláris kölcsönhatások: polimorfia és izostrukturalitás közötti összefüggések és ezek szimmetria tulajdonságainak krisztallográfiai vizsgálata = Crystallographic studies of supramolecular phenomena: correlation between polymorphism and isostructurality and their symmetry properties

A kémiailag rokon vegyületek szerkezete között észlelt nem-krisztallográfiai forgások rendszerezése arra a következtetésre vezetett, hogy azonosak Kitajgorodszkij (1961) morfotrópiájával (Kálmán, 2005). Majd kiderült, hogy Groth (1870) az első, aki a kristályok habitusában észlelte egyirányú változásokat morfotrópiának nevezte. Ez arra késztetett, hogy Groth morfológiai terminológiáját egybevessük Kitajgorodszkij szerkezeti morfotrópiájával. Újravizsgálva a Sn(C6H4R)4 származékokat megállapítottuk, hogy a morfotrópia egyformán lefedi a nem-krisztallográfiai forgásokat és transzlációkat (nkf/t-ók). Váratlanul kiderült, hogy a 2,4,6-trifenoxi-1,3,5-triazinok Piedfort egységei (PE-k) is nkf/t-ók kapcsolta izostrukturális csoportokat formálnak (Báthori, 2006). Először a PE-k az irodalomban hibákkal kevert szimmetriáit C3, C3i és D3 korrigáltuk Majd az aril szubsztitúciók hatásait vetettük össze: hogyan hatnak az o-, m- és p- szubsztituensek a Piedfort szimmetriákra, s mik a közös motívumaik a nkf/t-ók kapcsolta prototípusoknak? Vizsgálataink azt sugallják, hogy a korlátolt flexibilitású molekulák által gyakran mutatott nkf/t-ók a morfotrópia szupramolekuláris formái. A szerkezeti változatosságok, amit az általunk egyidejüleg meghatározott 4,1-benzotiazepinek kristályszerkezetek három dezmotróp párban mutatnak, segíteni látszanak a polimorfia és a dezmotrópia, valamint a polimorfia és izostrukturalitás morfotrópia létesítette bonyolult kapcsolatának megvilágításában. | The systematization of non-crystallographic rotations observed between the structures of chemically related molecules (Kálmán, 2005) led to the recognition of morphotropism as suggested by Kitaigorodskii (1961). Then it turned out that Groth (1870) was the first who denoted 'unidirectional changes' in the crystal habits morphotropy. This prompted us to collate Groth's morphological terms with Kitaigorodskii's structural morphotropism. Reinvestigating Sn(C6H4R)4 derivatives we concluded that morphotropism equally covers both forms of non-cryst. rotation and translation (ncr/t-s). Unexpectedly, the Piedfort units (PUs) of 2,4,6-tris-phenoxy-1,3,5-triazines studied by Báthori, (2006) revealed several isostructural groups linked by ncm-s. First we revisited the symmetries of PUs C3, C3i and D3 disclosed erroneously in the literature. Then we compared the effects of aryl substitutions: how do the o-, m-or p- functions influence the Piedfort symmetries and what are the common motives of the prototypes linked by ncr/t-s? Our investigations suggested that ncr/t-s observed frequently between semirigid molecules are supramolecular forms of morphotropism. The structural diversity exhibited by three pairs of desmotropic crystals of 4,1-benzothiazepines determined simultaneously in our laboratory seem to help to shed light on the complicated relationship between polymorphism and desmotropy, polymorphism and isostructurality via morphotropism

On the Nature of Hypervalent S-O Bonds in Sulfuranes

Sulfuranes with pseudo-trigonal-bipyramidal geometry are hallmarked by two apical hypervalent S-0 bonds. According to Musher’s classification, the quasi-linear arrangement of the atoms involved can be interpreted approximately in terms of an s-p basis, assuming four-electron-three-center bonds. However, substantial differences between the electronegativities of the apical groups give rise to rather unsymmetric three-center bonds. In spirosulfuranes, the unsymmetric polarization of the O-S-O bonds is terminated at around an interatomic distance of 2.26 Å, balanced by an S-0 single bond with a length of 1.63 Å. These asymmetric O-S-O bonds are formed in sulfonium salts with spirosulfurane geometry. Further asymmetry of the O-S • • • O grouping can be generated only for two-electron-three-center bonds formed by S(H) atoms. After a few guidelines on the basic forms of sulfuranes, starting with SF4, a short review of the analogous azasulfuranes and their sulfonium salts is presented, demonstrating how the N lone pair participates in the formation of S(IV)-N multiple bonds which, in turn, terminate the hypervalent bonds. These three centers possess only three electrons and form a transitional state with long S---0 single-bond/no-bond resonance interactions (2.13-2.80 Å) between four-electron-three-center (he. hypervalent) bonds and two-electron-three-center bonds. The unsymmetric sulfuranes (or sulfonium cations) are best described by six-electron-five-center bond models. S-O bonds retaining a bond number of at least n = 1/4 can still be regarded as hypervalent. Further polarization (n 0.8) results in three-electron-three-center systems with no hypervalent character

On the Hydrogen Bonding of Succinimide Derivatives: Crystal Structure of 3(4-Pyridil-methyl)amino-pyrrolidine-2,5-dione

The structure of 3(4-pyridil-methyl)amino-pyrrolidine-2,5-dione has been established by X-ray crystallography from diffractometer data with an F2 refinement to R = 0.0526 for 1999 observed reflections. The close packing of orthorhombic crystals space group Pbca (No. 61) with a = 11.595(4), b = 8.325(1), c = 20.452(4) Å, V = 1974.2(8) Å3, Z = 8, Dc = 1.381 Mg/m3, m = 0.824 mm–1 is built of herringbone-like molecular layers folded along the c axis and fused together by infinite chains of NH⋅⋅⋅O and NH⋅⋅⋅N hydrogen bonds perpendicular to one another. This prompted us to review and characterize the hydrogen bond networks formed by succinimides possessing an unsubstituted >NH group by the use of the Cambridge Structural Database (CSD), and our own earlier structure determinations. The common motifs of the hydrogen bond systems are analyzed using graph descriptions suggested by M. C. Etter. The influence of the hydrogen bonds on molecular close packing is also discussed

On the Hydrogen Bonding of Succinimide Derivatives: Crystal Structure of 3(4-Pyridil-methyl)amino-pyrrolidine-2,5-dione

The structure of 3(4-pyridil-methyl)amino-pyrrolidine-2,5-dione has been established by X-ray crystallography from diffractometer data with an F2 refinement to R = 0.0526 for 1999 observed reflections. The close packing of orthorhombic crystals space group Pbca (No. 61) with a = 11.595(4), b = 8.325(1), c = 20.452(4) Å, V = 1974.2(8) Å3, Z = 8, Dc = 1.381 Mg/m3, m = 0.824 mm–1 is built of herringbone-like molecular layers folded along the c axis and fused together by infinite chains of NH⋅⋅⋅O and NH⋅⋅⋅N hydrogen bonds perpendicular to one another. This prompted us to review and characterize the hydrogen bond networks formed by succinimides possessing an unsubstituted >NH group by the use of the Cambridge Structural Database (CSD), and our own earlier structure determinations. The common motifs of the hydrogen bond systems are analyzed using graph descriptions suggested by M. C. Etter. The influence of the hydrogen bonds on molecular close packing is also discussed

Fine tuning of crystal architecture by intermolecular interactions: synthon engineering

There has been a long time effort to influence or favourably fine tune structural properties by introduction of substituents or guest molecules of different sizes, shapes and chemical composition to consequently alter physico-chemical properties of the respective crystals. These attempts require the recognition, understanding and application of intermolecular interactions, crystallographic and, in case of occurrence, non-crystallographic symmetries. It brings us to the field of crystal engineering, which aims to produce new substances with required properties based on the knowledge of the structural properties of already characterised solids. A series of calixarene crystal structures are presented where the crystal packing is determined by spatial or by electrostatic effects. A series of laterally substituted calixarenes where both steric requirements and electrostatic forces play a role in the crystal architecture shows how the supramolecular synthon can be engineered

Magyar Tanítóképző 10 (1895) 09

Magyar Tanítóképző A Tanítóképző-intézeti Tanárok Országos Egyesületének közlönye 10. évfolyam, 09. füzet Budapest, 1895. november h

On the Nature of Hypervalent S-O Bonds in Sulfuranes

Sulfuranes with pseudo-trigonal-bipyramidal geometry are hallmarked by two apical hypervalent S-0 bonds. According to Musher’s classification, the quasi-linear arrangement of the atoms involved can be interpreted approximately in terms of an s-p basis, assuming four-electron-three-center bonds. However, substantial differences between the electronegativities of the apical groups give rise to rather unsymmetric three-center bonds. In spirosulfuranes, the unsymmetric polarization of the O-S-O bonds is terminated at around an interatomic distance of 2.26 Å, balanced by an S-0 single bond with a length of 1.63 Å. These asymmetric O-S-O bonds are formed in sulfonium salts with spirosulfurane geometry. Further asymmetry of the O-S • • • O grouping can be generated only for two-electron-three-center bonds formed by S(H) atoms. After a few guidelines on the basic forms of sulfuranes, starting with SF4, a short review of the analogous azasulfuranes and their sulfonium salts is presented, demonstrating how the N lone pair participates in the formation of S(IV)-N multiple bonds which, in turn, terminate the hypervalent bonds. These three centers possess only three electrons and form a transitional state with long S---0 single-bond/no-bond resonance interactions (2.13-2.80 Å) between four-electron-three-center (he. hypervalent) bonds and two-electron-three-center bonds. The unsymmetric sulfuranes (or sulfonium cations) are best described by six-electron-five-center bond models. S-O bonds retaining a bond number of at least n = 1/4 can still be regarded as hypervalent. Further polarization (n 0.8) results in three-electron-three-center systems with no hypervalent character