LiEC(SiMe3)3 (E = Se, Te) as a new donor of chalcogen atoms for the generation of binary [(RxGey)Ez] cage compounds with unique structural features

The reaction of GeCl2·dioxane with LiEC(SiMe3)3 (E = Se, Te) shows unexpected products different from those of the previously presented reaction system GeCl2·dioxane/LiSC(SiMe3)3. Here, LiEC(SiMe3)3 (E = Se, Te) acts as a chalcogen atom donor and simultaneously as a substituent to give cage compounds of the composition [(RxGey)Ez] with unique structural features of the Ge/E cores. The molecular structures are presented together with a possible formation mechanism of the selenium/germanium cage compound [{((SiMe3)3CGe)2GeSe4}2(μ2-Se)2] supported by quantum chemical calculations.

Dinuclear organogermanium chalcogenide complexes as intermediates towards functionalized clusters

Reactions of R1GeCl3 (R1 = CMe2CH2COMe) with (Me3Si)2E (E = S, Se, Te) yield three new organogermanium chalcogenide complexes [(R1GeCl)2S2] (1), [(R1GeCl)2Se2] (2), and [(R1GeCl)2Te2] (3) with functionalized ligands R1 = CMe2CH2COMe. NMR titration experiments clearly demonstrate that these dimeric complexes are intermediates in the formation of the well-known sesquichalcogenide clusters [(R1Ge)4E6]. In striking contrast to related tin compounds that were recently reported, the mono-bridged complexes of the type "[(R1GeCl2)2E]" and defect-heterocubane-type clusters "[(R1Ge)3E4Cl]" do not form on the NMR time scale for E = S or Te, and only in traces for E = Se.

Recent advances in the self-assembly of polynuclear metal–selenium and –tellurium compounds from 14–16 reagents

The use of reagents containing bonds between group 14 elements and Se or Te for the self-assembly of polynuclear metal–chalcogen compounds is covered. Background material is briefly reviewed and examples from the literature are highlighted from the period 2007–2017. Emphasis is placed on the different classes of 14–16 precursors and their application in the targeted synthesis of metal–chalcogen compounds. The unique properties arising from the combination of specific 14–16 precursors, metal atoms, and ancillary ligands are also described. Selected examples are chosen to underline the progress in (i) controlled synthesis of heterometallic (ternary) chalcogen clusters, (ii) chalcogen clusters with organic functionalized surfaces, and (iii) crystalline open-framework metal chalcogenides.

Organotin Selenide Clusters and Hybrid Capsules

Several compounds with unique structural motifs that have already been known from organotin sulfide chemistry, but remained unprecedented in organotin selenide chemistry so far, have been synthesized. The reaction of [(R¹ Sn)₄ Se₆ ] (R¹ =CMe₂ CH₂ C(O)Me) with N₂ H₄ ⋅H₂ O/(SiMe₃ )₂ Se and PhN₂ H₃ /(SiMe₃ )₂ Se led to the formation of [{(R² Sn)₂ SnSe₄ }₂ (μ-Se)₂ ] (1; R² =CMe₂ CH₂ C(Me)NNH₂ ) and [{(R³ Sn)₂ SnSe₄ }₂ (μ-Se)₂ ] (2; R³ =CMe₂ CH₂ C(Me)NNPhH)). The addition of ortho-phthalaldehyde to [(R² Sn)₄ Se₆ ] yielded a cluster with intramolecular bridging of the organic groups, namely, [(R⁴ Sn₂ )₂ Se₆ ] (3; R⁴ =(CMe₂ CH₂ C(Me)NNCH)₂ C₆ H₄ ). The introduction of organic ligands with longer chains finally allowed the isolation of inorganic-organic capsules of the type [(μ-R)₃ (Sn₃ Se₄ )₂ ]X₂ , with R=(CMe₂ CH₂ C(Me)NNHC(O))₂ (CH₂ )₄ and X=[SnC₃ ], Cl (4 a, b) or R=CMe₂ CH₂ C(Me)NNH)₂ and X=[SnCl₃ ] (5). The capsules enclose solvent molecules and/or anions as guests. All compounds were characterized by means of single-crystal X-ray diffraction studies, NMR spectroscopy, and mass spectrometry.

Formation and Reactivity of Organo-Functionalized Tin Selenide Clusters

Reactions of R(1) SnCl3 (R(1) =CMe2 CH2 C(O)Me) with (SiMe3 )2 Se yield a series of organo-functionalized tin selenide clusters, [(SnR(1) )2 SeCl4 ] (1), [(SnR(1) )2 Se2 Cl2 ] (2), [(SnR(1) )3 Se4 Cl] (3), and [(SnR(1) )4 Se6 ] (4), depending on the solvent and ratio of the reactants used. NMR experiments clearly suggest a stepwise formation of 1 through 4 by subsequent condensation steps with the concomitant release of Me3 SiCl. Furthermore, addition of hydrazines to the keto-functionalized clusters leads to the formation of hydrazone derivatives, [(Sn2 (μ-R(3) )(μ-Se)Cl4 ] (5, R(3) =[CMe2 CH2 CMe(NH)]2 ), [(SnR(2) )3 Se4 Cl] (6, R(2) =CMe2 CH2 C(NNH2 )Me), [(SnR(4) )3 Se4 ][SnCl3 ] (7, R(4) =CMe2 CH2 C(NNHPh)Me), [(SnR(2) )4 Se6 ] (8), and [(SnR(4) )4 Se6 ] (9). Upon treatment of 4 with [Cu(PPh3 )3 Cl] and excess (SiMe3 )2 Se, the cluster fragments to form [(R(1) Sn)2 Se2 (CuPPh3 )2 Se2 ] (10), the first discrete Sn/Se/Cu cluster compound reported in the literature. The derivatization reactions indicate fundamental differences between organotin sulfide and organotin selenide chemistry.

Synthesis and Thorough Investigation of Discrete Organotin Telluride Clusters

Systematic experimental and theoretical investigations of reactions of R(1)SnCl3 (R(1) = CMe2CH2C(Me)O) with (Me3Si)2Te allowed for the stepwise formation and single-crystalline isolation of the first tin sesquitelluride clusters with functional organic ligands. Subsequent derivatization of the latter took place under reorganization of the inorganic core, affording clusters with complex hybrid architectures.

Functionalized organotin-chalcogenide complexes that exhibit defect heterocubane scaffolds: formation, synthesis, and characterization

The synthesis of new functionalized organotin-chalcogenide complexes was achieved by systematic optimization of the reaction conditions. The structures of compounds [(R(1, 2) Sn)3 S4 Cl] (1, 2), [((R(2) Sn)2 SnS4 )2 (μ-S)2 ] (3), [(R(1, 2) Sn)3 Se4 ][SnCl3 ] (4, 5), and [Li(thf)n ][(R(3) Sn)(HR(3) Sn)2 Se4 Cl] (6), in which R(1) =CMe2 CH2 C(O)Me, R(2) =CMe2 CH2 C(NNH2 )Me, and R(3) =CH2 CH2 COO, are based on defect heterocubane scaffolds, as shown by X-ray diffraction, (119) Sn NMR spectroscopy, and ESI mass spectrometry analyses. Compounds 4, 5, and 6 constitute the first examples of defect heterocubane-type metal-chalcogenide complexes that are comprised of selenide ligands. Comprehensive DFT calculations prompted us to search for the formal intermediates [(R(1) SnCl2 )2 (μ-S)] (7) and [(R(1) SnCl)2 (μ-S)2 ] (8), which were isolated and helped to understand the stepwise formation of compounds 1-6.