According to the DFT calculations, [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (4), [1,2,5]selenadiazolo[3,4-c][1,2,5]thiadiazole (5), 3,4-dicyano-1,2,5-thiadiazole (6), and 3,4-dicyano-1,2,5-selenadiazole (7) have nearly the same positive electron affinity (EA). Under the CV conditions they readily produce long-lived π-delocalized radical anions (π-RAs) characterized by EPR. Whereas 4 and 5 were chemically reduced into the π-RAs with thiophenolate (PhS–), 6 did not react and 7 formed a product of hypercoordination at the Se center (9) isolated in the form of the thermally stable salt [K(18-crown-6)][9] (10). The latter type of reactivity has never been observed previously for any 1,2,5-chalcogenadiazole derivatives. The X-ray structure of salt 10 revealed that the Se–S distance in the anion 9 (2.722 A) is ca. 0.5 A longer than the sum of the covalent radii of these atoms but ca. 1 A shorter than the sum of their van der Waals radii. According to the QTAIM and NBO analysis, the Se–S bond in 9 can be consi...

Interaction of 1,2,5-Chalcogenadiazole Derivatives with Thiophenolate: Hypercoordination with Formation of Interchalcogen Bond versus Reduction to Radical Anion

Stereochemical activity of lone pairs of electrons and supramolecular aggregation patterns based on secondary interactions involving tellurium in its 1,1-dithiolate structures

The 3 centre-4 electrons (3c-4e) and the donor/acceptor or charge-transfer models for the description of the chemical bond in linear three-body systems, such as I3– and related electron-rich (22 shell electrons) systems, are comparatively discussed on the grounds of structural data from a search of the Cambridge Structural Database (CSD). Both models account for a total bond order of 1 in these systems, and while the former fits better symmetric systems, the latter describes better strongly asymmetric situations. The 3c-4e MO scheme shows that any linear system formed by three aligned closed-shell species (24 shell electrons overall) has reason to exist provided that two electrons are removed from it to afford a 22 shell electrons three-body system: all combinations of three closed-shell halides and/or chalcogenides are considered here. A survey of the literature shows that most of these three-body systems exist. With some exceptions, their structural features vary continuously from the symmetric situation showing two equal bonds to very asymmetric situations in which one bond approaches to the value corresponding to a single bond and the second one to the sum of the van der Waals radii of the involved atoms. This indicates that the potential energy surface of these three-body systems is fairly flat, and that the chemical surrounding of the chalcogen/halogen atoms can play an important role in freezing different structural situations; this is well documented for the I3– anion. The existence of correlations between the two bond distances and more importantly the linearity observed for all these systems, independently on the degree of their asymmetry, support the state of hypervalency of the central atom.

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The nature of the chemical bond in linear three-body systems: from i3- to mixed chalcogen/halogen and trichalcogen moieties.

Modulation of the coordination environment of silver(I) in bis(diphenylphosphino)methane complexes by selection of heterocyclic thiolato ligands

Solid state linear dichroic infrared spectral analysis of benzimidazoles and their N1-protonated salts

Mixed iodotris ( dithiocarbamato )tellurium(IV) complexes TeL3I (where L- = R1R2NCS2-) have been synthesized with the use of the oxidative replacement reaction via the interaction of TeL4 with iodine. Thus, complexes with R1 = R2 = methyl, ethyl, isopropyl, propyl, and with R1R2N= piperidinyl * have been prepared. A single-crystal structure analysis of one of these, iodotris ( piperidine dithiocarbamato )tellurium, is also reported. In the structure the tellurium atom exists in a distorted pentagonal-bipyramidal environment with the iodine atom and one sulfur atom occupying axial positions. The axial Te-S bond of 2.555(2) A is shorter than the remaining Te-S bonds in the complex [range 2.671(2)-2.722(2) A ]. Crystals are monoclinic, space group P2I/n with unit cell parameters a 9.891(2), b 18.889(2), c 14.762(2) A, β 98.85(2) and Z 4. The structure was refined to final R 0.035 and RW 0.052 for 3283 reflections with 1≥ 1.25 σI).

Preparation of Iodotris(dithiocarbamato)tellurium(Iv) Complexes, and Crystal Structure of Iodotris(piperidine-1-carbodithioato)tellurium(IV)

Synthesis of unusual mixed ligand tellurium(IV) dithiocarbamates with perchlorate. Crystal and molecular structure of perchloratotris(diethyldithiocarbamato)tellurium(IV)

The synthesis and crystal structure of the title complex are reported. Crystals are triclinic, space group with a = 10.359(2), b = 10.742(2), and c = 13.604(2) A, α = 87.25(1), β = 88.89(1), γ = 83...

Crystal structure of tris(o-phenylenethiourea)selenium(II) bromide pentahydrate, C21H18N6S3Br2Se•5H2O

The title compound is a novel mixed ligand and mixed valence complex of tellurium, the crystal structure of which is reported here. The compound crystallizes in the orthorhombic space group, Pca21 with four molecules per unit cell, the dimensions of which area=15.209(1),b=20.159(2),c=12.453(1) A. The structure was solved by the heavy-atom method and refined by fullmatrix least-squares method to a finalR=0.046 andRw=0.046 for 3011 unique reflections. The structure could be considered as 1∶1 adduct of TeIVL2I2 and TeIILI (L=diisopropyldithiocarbamate). The two tellurium atoms, TeII[Te(1)] and TeIV[Te(2)] display entirely different coordinations and are bridged through iodine I(1) in a symmetrical manner. There is a short Te(1)⋯Te(2) contact distance of 3.542(1) A.

Sp. Chidambaram

Papers

Preparation of Iodotris(dithiocarbamato)tellurium(Iv) Complexes, and Crystal Structure of Iodotris(piperidine-1-carbodithioato)tellurium(IV)

Synthesis of unusual mixed ligand tellurium(IV) dithiocarbamates with perchlorate. Crystal and molecular structure of perchloratotris(diethyldithiocarbamato)tellurium(IV)

Crystal structure of tris(o-phenylenethiourea)selenium(II) bromide pentahydrate, C21H18N6S3Br2Se•5H2O

A novel mixed valence iodide bridged Te(II)-Te(IV) complex featuring diisopropyldithiocarbamate(L) and iodide: ILTeII(I)TeIVL2I

Structure of 2-benzimidazolesulfonic acid monohydrate