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Intermolecular interactions of the new drug candidate sila-ibuprofen are investigated in the crystal and in the enzyme cyclooxygenase-II., Sila-ibuprofen is a new potential nonsteroidal anti-inflammatory drug which deviates from its parent ibuprofen in terms of the electrostatic potential around the carbon/silicon-switched C/Si—H group. Therefore, sila-ibuprofen is more water soluble and has a lower melting enthalpy. However, its binding and inhibition properties of cyclooxygenases appear to be very similar to regular ibuprofen. Therefore, in this study, intermolecular interactions and interaction densities of both ibuprofen and sila-ibuprofen in their biologically active forms, i.e. deprotonated and as the pure S-enantiomers are investigated. Quantum-crystallographically refined salts with argininium and 1-phenyl­ethan-1-amoninium (PEA) counter-cations as crystalline models of the interactions with the guanidine functional group of arginine inside cyclooxygenases are presented. The similarities and differences between the polarization of ibuprofen and sila-ibuprofen in the crystal, enzyme, solvent and isolated environments are discussed based on quantum-chemical calculations. For the explicit crystal and enzyme environments, specifically, molecular dynamics simulations starting from the crystal models were combined with QM/MM calculations.

The title compound, C12H24O2 2+·2CF3O3S−, is the first bisoxonium salt for which a crystal structure is reported. The cation is located on an inversion centre and it features a nonplanar C3O+ oxonium unit where the O atom is displaced by 0.375 (2) Å from the plane of its substituents.

In the crystal structure of the title compound, C10H10N3+·Cl-·[P(O)(OH)2H], the chloride ion and phosphorous acid form a one-dimensional hydrogen-bonded chain, while the 2-(2-pyridylamino)pyridinium cations form a second chain through [π]-[π] stacking. The two parallel chains are connected via a PO...H-N hydrogen bond and a weak pyridinium-to-chloride interaction.

Unlike the previously known monoclinic form, the ortho­rhombic polymorph of di­chloro­bis­[4-(di­methyl­amino)­phenyl]­tellurium, C16H20Cl2N2Te, shows secondary Te⋯Cl interactions.

The previously described structure of di­phenyl­tellurium dibromide, C12H10Br2Te, has been reinvestigated. The molecule lies on a twofold rotation axis.

The title compound, [Sn 2 Te 2 (C 4 H 9 ) 4 (CO 3 ) 2 O 2 (C 8 H 10 N) 4 ]·4CHCl 3 or [( p -Me 2 NC 6 H 4 ) 2 TeOSn t Bu 2 CO 3 ] 2 ·4CHCl 3 , contains an almost planar centrosymmetric inorganic Sn 2 Te 2 O 8 C 2 core and hypercoordinated Sn and Te atoms. The structure features four secondary intramolecular Te...O contacts.

The dimeric title compound, tetrabutyldiphenoxydistannoxane, [Sn 4 (C 4 H 9 ) 8 (C 6 H 5 O) 4 O 2 ], adopts a ladder-type structure, featuring an almost planar inorganic framework with three four-membered Sn 2 O 2 rings and four coplanar phenoxy groups.

The centrosymmetric hexanuclear title compound, hexa-μ2-acetato-hexa-μ3-oxo-hexakis­[(tri­methyl­silyl­methyl)­tin], [Sn6O6(C2H3O2)6(C4H11Si)6], adopts a `drum' structure in which two [(Me3SiCH2)SnO]3 caps are linked to each other via six μ3-O atoms and six bidentate bridging acetate groups. A CO5 donor set defines a distorted octahedral environment for each of the three independent Sn atoms.