Supertetrahedral chalcogenido (semi)metalate clusters have been in the focus of inorganic and materials chemistry for many years owing to a variety of outstanding physical and chemical properties. However, a critical drawback in the canon of studying corresponding compounds has been the lack of control in assembling the supertetrahedral units, which have been known as either highly charged monomeric cluster anions or lower charged, yet extended anionic substructures of linked clusters. The latter is the reason for the predominance of applications of such materials in heterogeneous environment, or their solubilization by organic shielding, which in turn was unfavorable regarding the optical properties. Recently, we reported a partial alkylation of such clusters, which allowed for a significantly enhanced solubility at a marginal impact on the optical gap. Herein we showcase the formation of finite cluster oligomers of supertetrahedral architectures by ionothermal syntheses. We were successful in generating the unprecedented dimers and tetramers of the [Ge 4 Se 10 ] 4– anion in salts with imidazolium-based ionic liquid counterions. The oligomers exhibit lower average negative charges and thus reduced electrostatic interactions between anionic clusters and cationic counterions. As a consequence, the salts readily dissolve in common solvents like DMF. Besides, the tetrameric [Ge 16 Se 36 ] 8– anion represents the largest discrete chalcogenide cluster of a group 14 element. We prove that undestroyed cluster oligomers can be transferred into solution by means of electrospray ionization (ESI) mass spectrometry and provide a full set of characteristics of the compounds including crystal structures and optical properties.
The reaction between [Li(dme)AsH2] and (ClSiiPr2)2O gives a mixture of two products: the primary diarsanyldisiloxan (H2AsSiiPr2)2O (5) and the cyclic diarsanylsiloxane (HAsSiiPr2)2O (6). Through metallation of the mixture, the deprotonated species of both compounds could be obtained and isolated. Further reactions between the two metallated cyclic diarsanylsiloxanes (compounds 9 and 10) and (ClSiiPr2)2O both lead to the bicyclic compound As2[(iPr2Si)2O]2 (11). Subsequent oxidative coupling of 9 or 10 with C2H4Br2 as reagent leads to intermolecular As–As bond formation, yielding the quite remarkable compound As6[(iPr2Si)2O]3 (12), which features two siloxane‐bridged As3 rings. Compounds 5–12 were characterized by NMR, elemental analysis and X‐ray crystallography. Quantum chemical calculations were carried out to investigate the formation of the different products when arsenic (compound 12) is substituted by phosphorus (compound 4) in the final oxidation reaction of the cyclic compounds (HESiiPr2)2O. The calculations suggest a reaction path leading to 4 that is in agreement with experimental observations. The theoretical data also provide information that explains the experimental finding that two different products for E = P and E = As are formed under the same oxidative reaction conditions.
Three new ternary selenidocadmates, K6[CdSe4] (1), K2[CdSe2] (2), and K2[Cd3Se4] (3), were synthesized and isolated upon fusion of K2Se and CdSe in respective stoichiometric amounts, followed by aminothermal treatment with 1,2‐diaminoethane. The anionic substructures range from molecules (0D, 1) through strands (1D, 2) to layered motifs (2D, 3). Compound 1 is isostructural to the corresponding mercury compound, K6[HgSe4], whereas the structure of 3 was previously predicted according to powder diffraction data, and could now be confirmed. The 1D chains in the anion of 2 represent a novel anionic architecture for this class of compounds. Determination of optical absorption properties confirm the expected decrease of the onset‐of‐absorption energies with increasing dimensionality of the anionic structures along the series of compounds. The structures of 1–3 were determined by means of single‐crystal Xray diffraction, and the heavy‐atom composition of the compounds was confirmed by micro Xray fluorescence spectroscopy (μ‐XFS).
The phases of "PbCh2" (Ch = Se, Te) are obtained from solid-state syntheses (i.e., by the fusion of the elements under inert conditions in silica glass ampules). Reduction of such phases by elemental alkaline metals in amines affords crystalline chalcogenidoplumbate(II) salts comprised of [PbTe3] or [Pb2Ch3] anions, depending upon which sequestering agent for the cations is present: crown ethers, like 18-crown-6, or cryptands, like [2.2.2]crypt. Reactions of solutions of such anions with transition-metal compounds yield (poly-)chalcogenide anions or transition-metal chalcogenide clusters, including one with a µ-PbSe ligand (i.e., the heaviest-known CO homolog). In contrast, the solid-state synthesis of a phase of the nominal composition "K2PbSe2" by successive reactions of the elements and by the subsequent solvothermal treatment in amines yields the first non-oxide/halide inorganic lead(IV) compound: a salt of the ortho-selenidoplumbate(IV) anion [PbSe4]. This was unexpected due to the redox potentials of Pb(IV) and Se(-II). Such methods can further be applied to other elemental combinations, leading to the formation of solutions with binary [HgTe2] or [BiSe3] anions, or to large-scale syntheses of K2Hg2Se3 or K3BiSe3 via the solid-state route. All compounds are characterized by single-crystal X-ray diffraction and elemental analysis; solutions of plumbate salts can be investigated by Pb andSe or Te NMR techniques. Quantum chemical calculations using density functional theory methods enable energy comparisons. They further allow for insights into the electronic configuration and thus, the bonding situation. Molecular Rh-containing Chevrel-type compounds were found to exhibit delocalized mixed valence, whereas similar telluridopalladate anions are electron-precise; the cluster with the µ-PbSe ligand is energetically favored over a hypothetical CO analog, in line with the unsuccessful attempt at its synthesis. The stability of formal Pb(IV) within the [PbSe4] anion is mainly due to a suitable stabilization within the crystal lattice.
The phases of "PbCh 2 " (Ch = Se, Te) are obtained from solid-state syntheses (i.e., by the fusion of the elements under inert conditions in silica glass ampules). Reduction of such phases by elemental alkaline metals in amines affords crystalline chalcogenidoplumbate(II) salts comprised of [PbTe 3 ] 2or [Pb 2 Ch 3 ] 2anions, depending upon which sequestering agent for the cations is present: crown ethers, like 18-crown-6, or cryptands, like [2.2.2]crypt. Reactions of solutions of such anions with transition-metal compounds yield (poly-)chalcogenide anions or transition-metal chalcogenide clusters, including one with a µ-PbSe ligand (i.e., the heaviest-known CO homolog).In contrast, the solid-state synthesis of a phase of the nominal composition "K 2 PbSe 2 " by successive reactions of the elements and by the subsequent solvothermal treatment in amines yields the first non-oxide/halide inorganic lead(IV) compound: a salt of the orthoselenidoplumbate(IV) anion [PbSe 4 ] 4-. This was unexpected due to the redox potentials of Pb(IV) and Se(-II). Such methods can further be applied to other elemental combinations, leading to the formation of solutions with binary [HgTe 2 ]2or [BiSe 3 ] 3anions, or to large-scale syntheses of K 2 Hg 2 Se 3 or K 3 BiSe 3 via the solid-state route.All compounds are characterized by single-crystal X-ray diffraction and elemental analysis; solutions of plumbate salts can be investigated by 205 Pb and 77 Se or 127Te NMR techniques. Quantum chemical calculations using density functional theory methods enable energy comparisons. They further allow for insights into the electronic configuration and thus, the bonding situation. Molecular Rh-containing Chevrel-type compounds were found to exhibit delocalized mixed valence, whereas similar telluridopalladate anions are electron-precise; the cluster with the µ-PbSe ligand is energetically favored over a hypothetical CO analog, in line with the unsuccessful attempt at its synthesis. The stability of formal Pb(IV) within the [PbSe 4 ] 4anion is mainly due to a suitable stabilization within the crystal lattice.
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