Search

Ag0.8In2.4Te4 (= AgIn3Te5) and Ag0.5In2.5Te4 (= AgIn5Te8) form solid solutions with CdIn2Te4, which are interesting as materials for photovoltaics or with respect to their thermoelectric properties. The corresponding crystal structures are related to the chalcopyrite type. Rietveld refinements of high-resolution synchrotron powder diffraction data measured at K-absorption edges of Cd, Ag, In, and Te and electron diffraction reveal the symmetry as well as the element and vacancy distribution in Ag0.8In2.4Te4 (= AgIn3Te5)/Ag0.5In2.5Te4 (= AgIn5Te8) mixed crystals such as Ag0.25Cd0.5In2.25Te4 and Ag0.2Cd0.75In2.1Te4. All compounds of the solid solution series (CdIn2Te4)x(Ag0.5In2.5Te4)1-x exhibit the HgCu2I4 structure type (space group I4̅2m) with completely ordered vacancies but disordered cations. The uniform cation distribution and thus the local charge balance are comparable to that of CdIn2Te4. In contrast, Ag0.8In2.4Te4 (= AgIn3Te5) crystallizes in the space group P4̅2c with disordered cations and partially ordered vacancies. This is corroborated by bond-valence sum calculations and the fact that there is a Vegard-like behavior for compounds with 0.5x in the pseudobinary system (CdIn2Te4)x(Ag0.8In2.4Te4)1-x. Owing to the different structures, there is no complete solid solution series between CdIn2Te4 and AgIn3Te5. All compounds in this work are n-type semiconductors with a low electrical conductivity (∼1 S/m) and rather high absolute Seebeck coefficients (up to -750 μV/mK; 225 °C). Electrical band gaps (Eg) determined from the Seebeck coefficients as well as (more reliably) from the electrical conductivity range between 0.19 and 1.13 eV.

The synthesis of inorganic N–P(III)-Ch-based macrocycles [−PhP–NMe–PPh–Ch−]2 (8Ch; Ch = S, Se) is presented by incorporating two nitrogen, two chalcogen, and four phosphorus atoms. The macrocycles are conveniently obtained via the cyclocondensation reaction of Na2Ch (Ch = S, Se) with the acyclic dichlorodiphosphazane ClPhP–NMe–PClPh (9). Treatment with elemental sulfur (S8) or gray selenium (Segray) results in an oxidative ring contraction to give 1,3,2,4-thiazadiphosphetidine 2,4-disulfide (10S) and 1,3,2,4-selenazadiphosphetidine 2,4-diselenide (10Se), respectively. Macrocycles 8Ch are excellent multidentate ligands for transition metal complexation, as demonstrated by the isolation of mono-, di- tri-, and tetranuclear silver sandwich complexes. The polynuclear silver complexes are comprehensively characterized, including detailed NMR and X-ray analysis.

A high-yielding and facile synthesis for diphosphane monochalcogenides (1(Ch)((R))) and their constitutional isomers, diphosphanylchalcoganes (2(Ch)((R))), was developed, featuring a condensation reaction between chlorophosphanes (R2PCl) and sodium chalcogenides (Na2Ch, Ch = S, Se, (Te)). The optimized protocol selectively yields either 1(Ch)((R)) (R2(Ch)PPR2) or 2(Ch)((R)) (Ch(PR2)2) depending upon the steric demand of the substituents R. Reaction pathways consistent with the distinct reaction outcomes are proposed. The application of 1(Ch)((R)) and 2(Ch)((R)) as an interesting class of ligands is exemplarily demonstrated by the preparation of selected transition metal complexes.

Herein we report on reactions of "imidazoliumyl-transfer" reagents [L((R/R'))SiMe3][OTf] (4((R/R'))[OTf]); L = imidazolium-2-yl, R/R': Me/Me, (i)Pr/Me, Dipp/H, Dipp/Cl) with pnictogen trichlorides PnCl3 (Pn = P, As, Sb) in various stoichiometries. In the case of the 1:1 reaction of [L((R/R'))SiMe3][OTf] with PCl3 the corresponding cationic imidazoliumyl-substituted dichlorophosphanes [L((R/R'))PCl2](+) (1P((R/R')))(+) are obtained as triflate salts on a multigram scale. We found that the reactions using various stoichiometries of [L((R/R'))SiMe3][OTf] and PnCl3 are less selective in the case of the heavier congeners or by decreasing steric demand of the R-group attached to the N atoms of the heterocycle. An equilibrium between the monocation [L((Me/Me))PCl2](+) (1P((Me/Me)+)), the dication [L((Me/Me))2PCl](2+) (2P((Me/Me)2+)), and the trication [L((Me/Me))3P](3+) (5P((Me/Me)3+)) is observed in solution. Reactions of the monocationic derivatives [L((R/R'))PnCl2][OTf] (Pn = P, As) with Me3SiX (X = CN, N3) resulted in the exchange of the chloro groups for the respective pseudohalogen and yielded the dicyano [L((R/R'))Pn(CN)2][OTf] (6Pn((R/R'))[OTf]) and diazido-substituted pnictanes [L((R/R'))Pn(N3)2][OTf] (7Pn((R/R'))[OTf]), respectively. All new compounds are thoroughly characterized by multinuclear NMR, IR, and Raman spectroscopy. For most cases the molecular structure was confirmed by X-ray crystal structure analysis.