Short Intramolecular O···O Contact in Some o-Dialkoxybenzene Derivatives Generates Efficient Hydrogen Bonding Acceptor Area

Statistical analysis of data extracted from the Cambridge Structural Database (CSD) has been used to investigate the crystal structure properties of odialkoxybenzene derivatives, compounds containing two ether oxygen acceptors in ortho positions of benzene ring. It has been shown that in more than 90% of cases, the fragment has predictable geometrical characteristics where the two ether oxygens form short interatomic O center dot center dot center dot O contact (2.57 A in average), while O-substitutents take trans position, both approximately coplanar with the benzene ring. Such arrangement of oxygen acceptors produces a large and uniform area of the negative electrostatic potential suitable for multiple hydrogen bonding. The acceptor abilities of the O center dot center dot center dot O system have been investigated by the statistical CSD analysis. The ab initio estimation of the interaction energy in the dimer of o-dimethoxybenzene (DMB) and H2O, employed as a model system, is achieved via high-level electron correlation CCSD(T) calculation with the complete basis set extrapolation. The interaction energy is estimated to be 6.5 kcal/mol. The results indicate the existence of a very flat potential the region between methoxy oxygens and that DMB water is a highly flexible system. The structural role of the O center dot center dot center dot O acceptor system is particularly interesting considering its ability to form multiple hydrogen bondingThe peer-reviewed version: [https://cer.ihtm.bg.ac.rs/handle/123456789/4283]The supplementary information: [https://cer.ihtm.bg.ac.rs/handle/123456789/4479

Endovenous laser ablation of the great saphenous vein in patients with von willebrand disease

Introduction Patients with von Willebrand disease have a high risk of bleeding during the surgical treatment of varicose veins. Endovenous laser ablation (EVLA) of the great saphenous vein (GSV) is a minimally invasive treatment for saphenofemoral junction incompetence. Th e number of complications and relapse rate of EVLA are lower than in those of conventional surgical treatment. Case presentation A patient with great saphenous vein insuffi ciency, von Willebrand disease and hypofi brinogenemia successfully underwent endovenous laser ablation. Replacement therapy with cryoprecipitate was administered preoperatively and postoperatively. Th e surgical procedure and postoperative course were unremarkable. Conclusion In patients with von Willebrand disease and other coagulation disorders, endovenous laser ablation is a safe and effective treatment. Th e use of minimally invasive treatment, the adequate correction of haemostasis, and close cooperation between the haematologist, anaesthesiologist and endovascular surgeon reduce the risk of bleeding

4-[(4-Methylphenyl)sulfanyl]butan-2-one

In the title compound, C11H14OS, all non-H atoms are essentially coplanar, with a mean deviation of 0.023 Å. In the crystal, centrosymmetrically related molecules are weakly connected into dimers by pairs of C - H⋯O interactions. The dimers are further linked along the a axis by weak C - H⋯π and C - H⋯S interactions

3-(3-Acetylanilino)-1-ferrocenylpropan-1-one

The title ferrocene-containing Mannich base, [Fe(C5H 5)(C16H16NO2)], crystallizes with two independent molecules (A and B) in the asymmetric unit. Molecules A and B have similar conformations. The dihedral angles between the best planes of the benzene and substituted cyclopentadienyl rings are 88.59 (9) and 84.39 (10)° in A and B, respectively. In the crystal, the independent molecules form centrosymmetric dimers via corresponding N - H⋯O hydrogen bonds. The dimers further arrange via C - H⋯π and C - H⋯O interactions. There are no significant interactions between the A and B molecules. © 2012 International Union of Crystallography

1-Ferrocenyl-3-(2-methylanilino)propan-1-one

In the ferrocene-containing Mannich base, [Fe(C5H 5)(C15H16NO)], the dihedral angle between the mean planes of the benzene ring and the substituted cyclopentadienyl ring is 84.63 (7)°. The conformation of the title compound significantly differs from those found in corresponding m-tolylamino and p-tolylamino derivatives. In the crystal, C - H⋯O interactions connect the molecules into chains, which further interact by means of C - H⋯π interactions. It is noteworthy that the amino H atom is shielded and is not involved in hydrogen bonding. © 2012 International Union of Crystallography

Benzyl 2-(benzylsulfanyl)benzoate

In the title compound, C21H18O2S, the central aromatic ring makes dihedral angles of 5.86 (12) and 72.02 (6)° with the rings of the terminal O-benzyl and S-benzyl groups, respectively. The dihedral angle between the peripheral phenyl rings is 66.16 (6)°. In the crystal, molecules are linked by pairs of C - H⋯O hydrogen bonds, forming inversion dimers. These dimers are linked via C - H⋯π interactions, forming a three-dimensional network

4-Ethoxy-3-methoxybenzaldehyde

In the title compound, C10H12O3, all non-H atoms are approximately coplanar, with an r.m.s. deviation of 0.046 Å. In the crystal, very weak C-H⋯O interactions link the molecules into sheets parallel to (101)

Experimental electron density distribution of bis(thiosemicarbazide)-zinc(II) dinitrate

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Electronic features and hydrogen bonding capacity of the sulfur acceptor in thioureido-based compounds. Part 2. Further insight by theoretical charge density study

Theoretical charge density analysis of the thioureido based compound 4-methyl-3-thiosemicarbazide (MeTSC) is used in this study with the aim to provide additional insight into electronic features of the thioureido sulfur acceptor and the corresponding D-H...S hydrogen bonding (D=N, C). The present work is motivated by our earlier experimental charge density study on the same compound that pointed out to a great flexibility of the thioureido S acceptor and its ability to adjust the lone pair electron density to the donor groups in simultaneous hydrogen bonding. Through the additional theoretical approach we were able to single out different fragments of MeTSC crystal and to carefully follow the changes in electron density properties of the S acceptors belonging to: isolated MeTSC monomers (i.e. two crystallographically independent molecules), eight D-H...S bonded dimers and MeTSC molecules placed in full crystal environment, where each S atom engages in four hydrogen bonds. Deformation density of the sulfur's lone electron pair, topological properties of D-H...S interactions and electrostatic potential are here examined in order to comprehend the mutual influence and potential cooperative effects of the four simultaneously formed interactions to each of the S acceptors. The hydrogen bonding involving thioureido S acceptor is also investigated in terms of the energetic properties of the eight real MeTSC dimers existing in the crystal structure, and additional systems MeTSC/MeOH and acetone/MeOH. The latter systems are designed with the purpose of direct comparison and ranking of interactions involving thioureido S to those involving more conventional, carbonyl O acceptor. Energetic features were thoroughly studied through electrostatic interactions energies (XD2006), cohesive energies (CRYSTAL09) and ab initio approach employing the coupled-cluster single S and doubles augmented by a perturbational correction for connected triple excitations (CCSD(T)) method

Experimental charge density study of salicylaldehyde thiosemicarbazone

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