Anna Dołęga

Intramolecular interactions in crystals of tris(2,6-diisopropylphenoxy)silanethiol and its sodium salts.

Hydrolytically stable silanethiol tris(2,6-diisopropylphenoxy)silanethiol (TDST) has been synthesized and reacted with sodium metal. In solid state TDST exhibits π-interactions between the S-H unit and the π-system of the arene, replaced by cation-π interactions in its sodium salts. The interactions are documented by crystal structures and FT-IR spectroscopy.

Two isomorphous ZnII/CoII complexes with tri-tert-butoxysilanethiol and histamine, and (4-hydroxymethyl-1H-imidazole-kappaN)bis(tri-tert-butoxysilanethiolato-kappa2O,S)zinc(II).

The complexes [2-(1H-imidazol-4-yl-kappaN(3))ethylamine-kappaN]bis(tri-tert-butoxysilanethiolato-kappaS)cobalt(II), [Co(C(12)H(27)O(3)SSi)(2)(C(5)H(9)N(3))], and [2-(1H-imidazol-4-yl-kappaN(3))ethylamine-kappaN]bis(tri-tert-butoxysilanethiolato-kappaS)zinc(II), [Zn(C(12)H(27)O(3)SSi)(2)(C(5)H(9)N(3))], are isomorphous. The central Zn(II)/Co(II) ions are surrounded by two S atoms from the tri-tert-butoxysilanethiolate ligand and by two N atoms from the chelating histamine ligand in a distorted tetrahedral geometry, with two intramolecular N-H...O hydrogen-bonding interactions between the histamine NH(2) groups and tert-butoxy O atoms. Molecules of the complexes are joined into dimers via two intermolecular bifurcated N-H...(S,O) hydrogen bonds. The Zn(II) atom in [(1H-imidazol-4-yl-kappaN(3))methanol]bis(tri-tert-butoxysilanethiolato-kappa(2)O,S)zinc(II), [Zn(C(12)H(27)O(3)SSi)(2)(C(4)H(6)N(2)O)], is five-coordinated by two O and two S atoms from the O,S-chelating silanethiolate ligand and by one N atom from (1H-imidazol-4-yl)methanol; the hydroxy group forms an intramolecular hydrogen bond with sulfur. Molecules of this complex pack as zigzag chains linked by N-H...O hydrogen bonds. These structures provide reference details for cysteine- and histidine-ligated metal centers in proteins.

Imidazolium silanethiolates relevant to the active site of cysteine proteases. A cooperative effect in a chain of NH+⋯S− hydrogen bonds

Three imidazolium silanethiolates relevant to the active site of cysteine proteases have been synthesized and investigated by X-ray diffraction, IR spectroscopy and computational methods. As indicated by crystallographic and FT-IR data in the solid state, the transfer of proton from thiol to imidazole takes place and a thiolato–imidazolium ion pair is formed. The FT-IR spectra of crystalline imidazolium silanethiolates exhibit intense continua characteristic for systems containing highly polarizable protons. DFT and ab initio HF calculations confirm the transfer of proton and prove the cooperativity of hydrogen bonds in the studied systems.

(4-Hydroxy­methyl-1H-imidazole-κN3)bis­(tri-tert-butoxy­silanethiol­ato-κ2O,S)cadmium(II)

The Cd(II) atom in the title compound, [Cd(C(12)H(27)O(3)SSi)(2)(C(4)H(6)N(2)O)], is penta-coordinated by two O and two S atoms from the O,S-chelating silanethiol-ate residue and one N from the 4-hydroxy-methyl-imidazole ligand and shows a strongly distorted trigonal-bipyramidal geometry. The title complex is isostructural with its zinc analog. The hydroxy group of the ligand is involved in intra-molecular O-H⋯S hydrogen bonding and also acts as an acceptor in the formation of an inter-molecular N-H⋯O hydrogen bond, which links mol-ecules of the complex into zigzag chains parallel to the b axis. One of the tert-butyl groups is disordered over two orientations with occupancies of 0.557 (12):0.443 (12).

Bromidotetra-kis-(2-isopropyl-1H-imidazole-κN)copper(II) bromide.

The CuII atom in the title salt, [CuBr(C6H10N2)4]Br, is coordinated in a square-pyramidal geometry by four imidazole N atoms and one bromide anion that is located at the apex of the pyramid. The cations and the anions form a two-dimensional network parallel to (001) through N—H⋯Br hydrogen bonds.

μ-4,4′-Bipyridyl-1:2κ2N:N′-methanol-2κO-tetrakis(tri-tert-butoxy­silanethiol­ato)-1κ4O,S;2κ2S-dizinc(II)

The title compound, [Zn2(C12H27O3SSi)4(C10H8N2)(CH4O)], is a binuclear complex with the two ZnII atoms linked via a bridging 4,4′-bipyridyl ligand. One of the ZnII atoms is penta-coordinated by two O,S-chelating tri-tert-butoxysilanethiolate units and one N atom of a 4,4′-bipyridine ligand, and the other ZnII atom is tetrahedrally coordinated by two tri-tert-butoxysilanethiolate anions acting as monodentate S ligands, the methanol O atom and the other N atom of the 4,4′-bipyridine ligand. This non-symmetrical coordination induces twisting and bending in the 4,4′-bipyridine ligand and introduces chirality into the system. The crystal studied exhibits inversion twinning. One tert-butyl group is disordered approximately equally over two positions.

Variable-temperature X-ray diffraction study of structural parameters of NH---S hydrogen bonds in triethylammonium and pyridinium silanethiolates

Two hydrogen-bonded, well defined compounds were synthesized from tris(2,6-diisopropyl)phenoxysilanethiol (TDST) and triethylamine (TDST-TEA) or pyridine (TDST-py). The crystalline compounds were characterized in the solid state by variable-temperature X-ray diffraction measurements and ATR FT-IR spectroscopy. The toluene solutions of TDST-TEA and TDST-py were studied by NMR spectroscopy. The total hydrogen-bond energies and FT-IR spectra were calculated with the use of BLYP-D/TZP and B3LYP/6-31G(d,p)/GD3BJ methods. Thermochemical parameters and potential energy scans were calculated at the B3LYP/6-31G(d,p)/GD3BJ level. All results point to the higher energy of bonding in TDST-TEA both in the solid state and in solution. At the same time the potential energy scan reveals a very broad double-well hydrogen bond in TDST-py, indicating good stabilization of the system for a wide range of D-H...A distances.

(1H-Pyrazole-κN)bis­(tri-tert-but­oxy­silane­thiol­ato-κ2O,S)cadmium

The CdII atom in the title complex, [Cd(C12H27O3SSi)2(C3H4N2)], is penta-coordinated by two O and two S atoms from the O,S-chelating silanethiolate residue and one pyrazole N atom in a distorted geometry that is slightly closer to trigonal–bipyramidal than to square-based pyramidal. The pyrazole ligand is stabilized within the complex by an intramolecular N—H⋯O hydrogen bond. One of the tert-butyl groups is disordered over two orientations with occupancy ratio of 0.534 (6):0.466 (6).

Bromidotetra-kis-(1H-2-ethyl-5-methyl-imidazole-κN)copper(II) bromide.

The CuII ion in the title compound, [CuBr(C6H10N2)4]Br, is coordinated in a square-based-pyramidal geometry by the N atoms of four imidazole ligands and a bromide anion in the apical site. Both the CuII and Br− atoms lie on a crystallographic fourfold axis. In the crystal, the [CuBr(C6H10N2)4]+ complex cations are linked to the uncoordinated Br− anions (site symmetry ) by N—H⋯Br hydrogen bonds, generating a three-dimensional network. The ethyl group of the imidazole ligand was modelled as disordered over two orientations with occupancies of 0.620 (8) and 0.380 (8).

Bromidotetra­kis­(2-ethyl-1H-imidazole-κN3)copper(II) bromide

The CuII ion in the title molecular salt, [CuBr(C5H8N2)4]Br, is coordinated in a square-pyramidal geometry by four N atoms of imidazole ligands and one bromide anion in the apical position. In the crystal, the ions are linked by N—H⋯Br hydrogen bonds involving both the coordinating and the free bromide species as acceptors. A C—H⋯Br interaction is also observed. Overall, a three-dimensional network results.