The structures of two new T-shaped selenyl chloride adducts studied by experimental (multinuclear NMR, IR, and Raman spectroscopy and X-ray diffraction analysis) and theoretical (ab initio and DFT quantum chemical calculations) methodsEur.

The title compound, [SnCl2(C5H4NS)2], is the product of reaction of 2,2′-dipyridyl disulfide with tin tetra­chloride. The SnIV atom adopts a distorted octa­hedral geometry, with the two bidentate pyridine-2-thiol­ate ligands forming two planar four-membered chelate rings. The two Sn—Cl, two Sn—N and two Sn—S bonds are in cis, cis and trans configurations, respectively. The crystal grown from acetonitrile represents a new monoclinic polymorph in space group C2/c with the mol­ecule having twofold rotational symmetry, the SnIV atom lying on the twofold axis. The mol­ecular structure of the monoclinic polymorph is very close to that of the triclinic polymorph studied previously in space group P-1, the mol­ecule occupying a general position [Masaki & Matsunami (1976 ▶). Bull. Chem. Soc. Jpn, 49, 3274–3279; Masaki et al. (1978 ▶). Bull. Chem. Soc. Jpn, 51, 3298–3301]. Apparently, the formation of the two polymorphs is determined by the different systems of inter­molecular inter­actions. In the crystal of the monoclinic polymorph, mol­ecules are bound into ribbons along the c axis by C—H⋯Cl hydrogen bonds, whereas in the crystal of the triclinic polymorph, mol­ecules form chains along the a axis by attractive S⋯S inter­actions. The crystal studied was a pseudo-merohedral twin; the refined BASF value is 0.221 (1).

Key indicators: single-crystal X-ray study; T = 100 K; mean (C-C) = 0.004 Å; R factor = 0.026; wR factor = 0.063; data-to-parameter ratio = 31.6.The title compound, [SnCl 2 (C 5 H 4 NSe) 2 ], is the product of a reaction of 2,2 0 -dipyridyl diselenide with tin tetrachloride. The molecule is located about a twofold rotation axis. The coordination environment of the Sn IV atom is a distorted octahedron, with two bidentate 2-pyridineselenolate ligands inclined to each other at an angle of 83.96 (7) . The two SnCl and two Sn-N bonds are in cis configurations, while the two Sn-Se bonds of 2.5917 (3) Å are in a trans configuration, with an Se-Sn-Se angle of 157.988 (15) . In the crystal, -interactions between the pyridine rings [centroid-to-centroid distance of 3.758 (3) Å ] and weak intermolecular C-HÁ Á ÁCl hydrogen bonds link the molecules into chains along the c axis. Related literature

The organic molecule in the title hydrate, C9H9N3O3·H2O, was obtained by the condenstation of salicylic aldehyde with urea in acetonitrile. The oxazine ring adopts a slightly distorted sofa conformation, with the N atom deviating from the plane passing through the other atoms of the ring by 0.267 (2) Å. The crystal structure displays inter­molecular N—H⋯O and O—H⋯O hydrogen bonding.

Among the rare classes of molecules that exhibit both reversible thermo and photochromism in the crystalline state, N-salicylidene aniline aminopyridine can be highlighted. [1] In this work, we have studied the influence of the increase of flexibility and electronic conjugation loss among N-salicylidene aminopyridine derivatives on the optical properties after the introduction of a methylene spacer. Five N -(5-chloro) N-methylbenzoimidazole-2-selone-dichlorine (1) and benzothiazole-2-selone-dichlorine (2) have been synthesized by the treatment of the corresponding selones with sulfuryl dichloride in dichloromethane. The X-ray crystal structure determinations of 1 and 2 show their 10E3 T-shaped hypervalent chalcogen adduct natures. The both structures are essentially zwitter-ionic, a negative charge resides on the SeCl 2 moiety and a positive charge is supported by the nitrogen atoms. The CSe distances of 1.896(2) Å in 1 and 1.898(2) Å in 2 are representative of the single bonds. Interestingly, the almost linear Cl-Se-Cl systems in 1 [174.60(2)] and 2 [179.41(2)] are differently orientated in relative to the organic fragment plane. In 1, the SeCl 2 moiety is roughly perpendicular to the benzoimidazole plane [68.73(3)], whereas, in 2, this moiety is approximately coplanar to the benzothiazole plane [3.0(1)] (see the figures below). Apparently, the observed planar conformation of 2 is explained by the absence of the steric hindrances, i.e., bulky substituent in the 1-position of the five-membered ring, for the formation of the strong intramolecular N3H3…Cl2 hydrogen bond. In the case of 1, the Cl2 chlorine atom forms the strong intermolecular N3H3…Cl2 hydrogen bond. Due to the hydrogen bonding interactions, the SeCl 2 moiety in 1 and 2 has the asymmetric geometry with the longer Se1Cl2 bond [2.5374(5) Å in 1 and 2.4622(6) Å in 2] as compared to the Se1Cl1 bond [2.3352(5) Å in 1 and 2.3377(6) Å in 2]. Thus, the structures of 1 and 2 clearly demonstrate the free rotation of the SeCl 2 moiety around the CSe bond that, in turn, confirms the absence of its significant double character.