Stereochemistry of seven-membered heterocycles. 3. Conformation of 5,6-dichloro-1,3-dioxacyclopent-5-enes and the planar-fragment effect

Author(s):  
B. A. Arbuzov ◽  
E. N. Klimovitskii ◽  
A. B. Remizov ◽  
V. V. Klochkov ◽  
A. V. Aganov ◽  
...  
Keyword(s):  
2013 ◽  
Vol 69 (11) ◽  
pp. o1698-o1698 ◽  
Author(s):  
Svitlana V. Shishkina ◽  
Igor V. Ukrainets ◽  
Lidiya A. Petrushova

There are two independent molecules in the asymmetric unit of the title compound, C13H13NO5S, in both of which the ester substituent is nearly coplanar [C—C—C—O torsion angles = 2.7 (7) and −0.8 (7)°] with the planar fragment of the bicycle due to the formation of a strong O—H...O intramolecular hydrogen bond. The vinyl group at the ring N atom is approximately orthogonal to the heterocyclic mean plane [C—N—C—C torsion angles = 103.1 (6) and 98.2 (5)°]. The refinement was performed on a two-component, non-merohedrally twinned crystal [population ratio = 0.483 (3):0.517 (3).


1997 ◽  
Vol 52 (3) ◽  
pp. 337-339 ◽  
Author(s):  
Larisa A. Kovbasyuk ◽  
Olga Yu. Vassilyeva ◽  
Vladimir N. Kokozay ◽  
Wolfgang Linert

Abstract A heterotetranuclear CuIIPbII complex containing 2-dimethylaminoethanol has been synthesized, using copper powder and PbBn2 as starting materials, and characterized by X-ray crystallography. The crystal is composed of centrosymmetric molecules [CuPbBr2{(CH3)2NCH2CH2O}2dmso]2. The central strictly planar fragment is a Pb2O2 parallelogram completed by bridging oxygen atoms of chelating 2-dimethylaminoethoxo groups. The Pb atom forms four quite short bonds with oxygen atoms of the three 2-dimethylaminoethoxo groups and of the dmso molecule and assumes a six-coordinate structure also involving two bromine atoms. The two oxygen and two nitrogen atoms of two 2-dimethylaminoethoxo groups form the copper coordination environment, which possesses a somewhat distorted square planar geometry.


2003 ◽  
Vol 59 (11) ◽  
pp. o605-o608 ◽  
Author(s):  
Vladimir N. Nesterov ◽  
Tatiana V. Timofeeva ◽  
Sergey S. Sarkisov ◽  
Alexander Leyderman ◽  
Charles Y.-C. Lee ◽  
...  

The structures of 3,5-bis[4-(diethylamino)benzylidene]-1-methyl-4-piperidone, C28H37N3O, (I), and 3,5-bis[4-(diethylamino)cinnamylidene]-1-methyl-4-piperidone, C32H41N3O, (II), have been characterized. Because of conjugation between donor and acceptor parts, the central heterocycles (including the carbonyl group) in (I) and (II) are flattened and exhibit a `sofa' conformation, with a deviation of the N atom from the planar fragment. The dihedral angles between the planar part of the heterocycle and the two almost flat fragments that include a phenyl ring and bridging atoms are 23.2 (1) and 11.2 (1)° in (I), and 11.8 (1) and 8.7 (2)° in (II). One- and two-photon absorption of light and the fluorescence of (I) and (II) have also been characterized.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Hong-Lei Xu ◽  
Nikolay V. Tkachenko ◽  
Zi-Chuan Wang ◽  
Wei-Xing Chen ◽  
Lei Qiao ◽  
...  

Abstract Sandwich-type clusters with the planar fragment containing a heterometallic sheet have remained elusive. In this work, we introduce the [K(2,2,2-crypt)]4{(Ge9)2[η6-Ge(PdPPh3)3]} complex that contains a heterometallic sandwich fragment. The title compound is structurally characterized by means of single-crystal X-ray diffraction, which reveals the presence of an unusual heteroatomic metal planar fragment Ge@Pd3. The planar fragment contains a rare formal zerovalent germanium core and a peculiar bonding mode of sp2-Ge@(PdPPh3)3 trigonal planar structure, whereas the nonagermanide fragments act as capping ligands. The chemical bonding pattern of the planar fragment consists of three 2c-2e Pd-Ge σ-bonds attaching Pd atoms to the core Ge atom, while the binding between the planar fragment and the aromatic Ge9 ligands is provided by six 2c-2e Pd-Ge σ-bonds and two delocalized 4c-2e σ-bonds. The synthesized cluster represents a rare example of a sandwich compound with the heteroatomic metal planar fragment and inorganic aromatic capping ligands.


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