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Chlorination of 3‐methyl‐5‐phenyl‐1,2‐tellurazole‐2‐oxide yielded the λ4Te dichloro derivative. Its crystal structure demonstrates that the heterocycle retains its ability to autoassociate by chalcogen bonding (ChB) forming macrocyclic tetramers. The corresponding Te⋅⋅⋅O ChB distances are 2.062 Å, the shortest observed to date in aggregates of this type. DFT−D3 calculations indicate that while the halogenated molecule is stronger as a ChB donor it also is a weaker ChB acceptor; the overall effect is that the ChBs in the chlorinated homotetramer are not significantly stronger. However, partial halogenation or scrambling selectively yield the 2 : 2 heterotetramer with alternating λ4Te and λ2Te centers, which calculations identified as the thermodynamically preferred arrangement. [ABSTRACT FROM AUTHOR]

N-Bonded adducts of benzo-2,1,3-selenadiazole with BX3 (X = Ph, F, Cl, Br) were prepared and crystallographically characterized. The structures of the 1 : 1 adducts of BF3 and BCl3 demonstrate dimerization through the [Se–N]2 supramolecular synthon and enhancement of the corresponding Se…N chalcogen bonding interactions. However, the structures of the BPh3 and BBr3 compounds indicate that other supramolecular interactions can efficiently compete and inhibit [Se–N]2 dimerization. In the case of the BPh3 adduct, dispersion favors a dimer featuring Se…C interactions. In the crystal of the BBr3 derivative, the cooperative effect of Se…N chalcogen bonding and Br…Br halogen bonding interactions lead to a network structure. A 1 : 2 adduct could be isolated only in the case of BCl3; its structure features short intramolecular Se…Cl interactions resulting from the enhanced electrophilic character of the chalcogen atom. [ABSTRACT FROM AUTHOR]

Abstract: The reactions of Li2[C(PPh2S)2] with EI3 (E = As, P) have been investigated in order to determine the nature of the coordination mode between the methanediide ligand and lighter pnictogens. Treatment of this reagent in toluene with AsI3 in a 1:1 M ratio produces the heteroleptic complex AsI[C(PPh2S)2] (2a), which was characterized by multinuclear NMR spectra and by a crystal structure determination. Attempts to isolate the phosphorus analogue PI[C(PPh2S)2] (2b) were unsuccessful. The dianionic methanediide ligand [C(PPh2S)2]2− in 2a is S,C,S-coordinated to the AsIII centre. The lengths of the weak As–S bonds differ markedly (2.852(2) and 2.443(2) Å) and the As–C bond distance 1.864(6) Å falls midway between single and double bond values. DFT calculations for AsI[C(PPh2S)2] reveal that the structure with a symmetrically coordinated ligand is lower in energy than the experimental structure by only 8.3 kJ mol−1 suggesting that the stabilization of the latter in the solid state is due to packing effects. The calculated bond orders for the M–C bond in MI[C(PPh2S)2] are 1.23 (M = As) and 1.31 (M = P). The π M–C interaction is predicted to be significantly stronger in the corresponding cations [M{C(PPh2S)2}]+ with bond orders of 1.68 (M = As) and 1.75 (M = P). [Copyright &y& Elsevier]

The compound previously reported as Ba2Ti2B2O9 has been reformulated as Ba3Ti3B2O12, or Ba3Ti3O6(BO3)2, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO3:BaTiB2O6 (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric P6¯2m space group, a=8.7377(11) A˚, c=3.9147(8) A˚, Z=1, wR(F2)=0.039 for 504 unique reflections. Ba3Ti3O6(BO3)2 is isostructural with K3Ta3O6(BO3)2. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba3Ti3O6(BO3)2 is equal to 95% of that of LiNbO3. [Copyright &y& Elsevier]

• Chalcogen bonding influences the structure and properties of functional materials. • Examples include charge transfer salts, neutral heterocyclic free radicals, and paramagnetic coordination compounds. • Examples of influenced optical properties include visible light absorption and nonlinear optical response. This review examines recent literature in search for evidence of the influence that chalcogen bonding has on the structure and properties of functional materials. Key examples from research on charge transfer salts, neutral heterocyclic free radicals, and paramagnetic coordination compounds are highlighted as intermolecular interactions are critical to properties such as conductivity and magnetic response. Other cases reviewed include the influence of chalcogen bonding on optical properties such as the electronic absorption spectra and the nonlinear optical response of non-centrosymmetric crystal structures. There is also evidence that this type of interaction between molecules translates into macroscopic mechanical properties such as the bulk modulus. [ABSTRACT FROM AUTHOR]