Ionothermal Access to Defined Oligomers of Supertetrahedral Selenido Germanate Clusters

Abstract

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.

Ion-Selective Assembly of Supertetrahedral Selenido Germanate Clusters for Alkali Metal Ion Capture and Separation

“…Reproducibly, the use of [Li 4 (H 2 O) 20.33 ]­[Ge 4 Se 10 ], Na 4 Ge 4 Se 10 , [K 4 (H 2 O) 3 ]­[Ge 4 Se 10 ], or Rb 4 [Ge 4 Se 10 ] did not afford crystals of compound 1 (see Scheme S1a) but led to the crystallization of crystals of compound (C 2 C 1 Im) 6 [Ge 8 Se 19 ] that we reported recently . As detailed in Scheme S1b, the addition of CsCl to such a reaction mixture caused the formation of compound 1 in all cases, as verified by SC-XRD.…”

“…To experimentally explore the selectivity of compound 1 for Cs + cations, we designed and performed a comprehensive series of cross-experiments, as detailed in Scheme S1 and summarized in Table 1. All reaction conditions were the same as those for the preparation of compound 1 (see Scheme S1, left hand side), except for the use of other alkali metal salts of the [Ge 4 Se 10 ] 20 As detailed in Scheme S1b, the addition of CsCl to such a reaction mixture caused the formation of compound 1 in all cases, as verified by SC-XRD. In addition, the yield of 1 from all controlled combinations is close to the number of the single-source formed one and is listed in Table S13.…”

“…Given the recent progress in chalcogenide cluster chemistry, − we consider supertetrahedral chalcogenido metalate cluster compounds (or networks of such clusters) with suitable cavities to be excellent candidates for the selective incorporation of A + ions. However, most compounds based on supertetrahedral chalcogenido metalate clusters that have been reported so far are structurally templated by organic ammonium cations (from neutral amines or ionic liquid cations), which occupy the cavities and can hardly be replaced.…”

Crystalline chalcogenidometalate-based compounds from uncommon reaction media

“…4h), were generated and isolated in single-crystalline form as salts. 81 The average negative charge per cluster unit was reduced from 4- in the parent cluster to 3- in the dimer and 2- in the tetramer. The correspondingly decreased electrostatic interaction between anions and cations allowed to readily dissolve the salts in DMF.…”

Competitive coordination and Lewis-base interactions of amines in supertetrahedral cluster-based materials by a controllable naked T3-InS precursor method: from isolated clusters with various substituted ligands, chains to 3-D open frameworks

“…For example, the synthesis strategies of ''multivalent metal complementarity'' and ''superbase-assisted crystallization'' proposed by Feng and co-workers offer significant theoretical guidance for the efficient preparation of MCSCs. [25][26][27] In last several years, Li, [28][29][30][31] Huang, [32][33][34] Stefanie Dehnen [35][36][37] and others have used ionic liquids to develop many unique MCSCs that are difficult to obtain from solvothermal synthesis, making thermal synthesis of ionic liquids one of the important means to obtain MCSCs. Both new synthesis strategies and new ionothermal synthesis methods have greatly promoted the development of MCSCs.…”