Knüpfung von Thiostannat-Sn-Sn-Bindungen in Lösung: In-situ-Bildung des gemischtvalenten funktionalisierten Komplexes [{(RSnIV)2(μ-S)2}3SnIII2S6]

Engesser T, Indris S, Zinkevich T, Näther C, Lühmann H, Reinsch H, Adams S, Bensch W. Room-Temperature Solid-State Transformation of Na4 SnS4 ⋅ 14H2 O into Na4 Sn2 S6 ⋅ 5H2 O: An Unusual Epitaxial Reaction Including Bond Formation, Mass Transport, and Ionic Conductivity

A highly unusual solid-state epitaxy-induced phase transformation of Na4 SnS4  ⋅ 14H2 O (I) into Na4 Sn2 S6  ⋅ 5H2 O (II) occurs at room temperature. Ab initio molecular dynamics (AIMD) simulations indicate an internal acid-base reaction to form [SnS3 SH]3- which condensates to [Sn2 S6 ]4- . The reaction involves a complex sequence of O-H bond cleavage, S2- protonation, Sn-S bond formation and diffusion of various species while preserving the crystal morphology. In situ Raman and IR spectroscopy evidence the formation of [Sn2 S6 ]4- . DFT calculations allowed assignment of all bands appearing during the transformation. X-ray diffraction and in situ 1 H NMR demonstrate a transformation within several days and yield a reaction turnover of ≈0.38 %/h. AIMD and experimental ionic conductivity data closely follow a Vogel-Fulcher-Tammann type T dependence with D(Na)=6×10-14  m2  s-1 at T=300 K with values increasing by three orders of magnitude from -20 to +25 °C.

Directed Dehydration as Synthetic Tool for Generation of a New Na 4 SnS 4 Polymorph: Crystal Structure, Na + Conductivity, and Influence of Sb‐Substitution

We present the convenient synthesis and characterization of the new ternary thiostannate Na₄SnS₄ (space group I41/acd ) by directed removal of crystal water molecules from Na₄SnS₄⋅14 H₂O. The compound represents a new kinetically stable polymorph of Na₄SnS₄, which is transformed into the known, thermodynamically stable form (space group P4‾21c ) at elevated temperatures. Thermal co‐decomposition of mixtures with Na₃SbS₄⋅9 H₂O generates solid solution products Na_4−xSn_1−xSb_xS₄ (x=0.01, 0.10) isostructural to the new polymorph (x=0). Incorporation of Sb⁵⁺ affects the bonding and local structural situation noticeably evidenced by X‐ray diffraction, ¹¹⁹Sn and ²³Na NMR, and ¹¹⁹Sn Mössbauer spectroscopy. Electrochemical impedance spectroscopy demonstrates an enormous improvement of the ionic conductivity with increasing Sb content for the solid solution (σ_25°C=2×10⁻³, 2×10⁻², and 0.1 mS cm⁻¹ for x=0, 0.01, and 0.10), being several orders of magnitude higher than for the known Na₄SnS₄ polymorph.

Selective replacement of organosilicon units in the cluster [(PhSi)4S6] with coinage metal complex fragments

Adamantane-type organo-group 14 chalcogenide clusters were shown to possess extreme non-linear optical properties. Reactivity studies of corresponding organosilicon sulfide clusters towards copper and silver complexes indicate a replacement of exactly one of the organosilicon groups with a metal complex fragment to form [(Et₃PAg)₃(PhSi)₃S₆] (1) and [Na₂(thf)_2.33][(Me₃PCu)(PhSi)₃S₆] (2)-in striking contrast to reactions of organotin chalcogenide clusters, which are more significantly and less systematically re-organized. The silicon compounds are thus more suited for controlled modifications of their geometric and electronic structures.

Pyrene-Terminated Tin Sulfide Clusters: Optical Properties and Deposition on a Metal Surface

Herein, we present the synthesis of two pyrene-functionalized clusters, [(Rpyr Sn)4 S6 ]⋅2 CH2 Cl2 (4) and [(Rpyr Sn)4 Sn2 S10 ]⋅n CH2 Cl2 (n=4, 5 a; n=2, 5 b; Rpyr =CMe2 CH2 C(Me)N-NC(H)C16 H9 ), both of which form in reactions of the organotin sulfide cluster [(RN Sn)4 S6 ] (C; RN =CMe2 CH2 C(Me)N-NH2 ) with the well-known fluorescent dye 1-pyrenecarboxaldehyde (B). In contrast, reactions using an organotin sulfide cluster with another core structure, [(RN Sn)3 S4 Cl] (A), leads to formation of small molecular fragments, [(Rpyr Cl2 Sn)2 S] (1), (pyren-1-ylmethylene)hydrazine (2), and 1,2-bis(pyren-1-ylmethylene)hydrazine (3). Besides synthesis and structures of the new compounds, we report the influence of the inorganic core on the optical properties of the dye, which was analyzed exemplarily for compound 5 a via absorption and fluorescence spectroscopy. This cluster was also used for exploring the potential of such non-volatile clusters for deposition on a metal surface under vacuum conditions.

Towards Understanding the Reactivity and Optical Properties of Organosilicon Sulfide Clusters

We report the extension of the class of organotetrel sulfide clusters with further examples of the still rare silicon-based species, synthesized from RSiCl3 with R=phenyl (Ph, I), naphthyl (Np, II), and styryl (Sty, III) with Na2 S. Besides known [(PhSi)4 S6 ] (IV), new compounds [(NpSi)4 S6 ] (1) and [(StySi)4 S6 ] (2) were obtained, the first two of which underwent reactions with [AuCl(PPh3 )] to form ternary complexes. DFT studies of cluster dimers helped us understand the differences between the habit of {Si4 S6 }- and {Sn4 S6 }-based compounds. Crystalline 1 showed a pronounced nonlinear optical response, while for intrinsically amorphous 2, the chemical damage threshold seems to inhibit a corresponding observation. Calculations within the independent particle approximation served to rationalize and compare electronic and optical excitations of [(RSi)4 S6 ] clusters (R=Ph, Np). The calculations reproduced the measured data and allowed for the interpretation of the main spectroscopic features.

MeSi(CH2 SnRO)3 (R=Ph, Me3 SiCH2 ): Building Blocks for Triangular-Shaped Diorganotin Oxide Macrocycles

The syntheses of the novel silicon-bridged tris(tetraorganotin) compounds MeSi(CH2 SnPh2 R)3 (2, R=Ph; 5, R=Me3 SiCH2 ) and their halogen-substituted derivatives MeSi(CH2 SnPh(3-n) In )3 (3, n=1; 4, n=2) and MeSi(CH2 SnI2 R)3 (6, R=Me3 SiCH2 ) are reported. The reaction of compound 4 with di-t-butyltin oxide (t-Bu2 SnO)3 gives the oktokaideka-nuclear (18-nuclear) molecular diorganotin oxide [MeSi(CH2 SnPhO)3 ]6 (7) while the reaction of 6 with sodium hydroxide, NaOH, provides the trikonta-nuclear (30-nuclear) molecular diorganotin oxide [MeSi(CH2 SnRO)3 ]10 (8, R=Me3 SiCH2 ). Both 7 and 8 show belt-like ladder-type macrocyclic structures and are by far the biggest molecular diorganotin oxides reported to date. The compounds have been characterized by elemental analyses, electrospray mass spectrometry (ESI-MS), NMR spectroscopy, 1 H DOSY NMR spectroscopy (7), IR spectroscopy (7, 8), and single-crystal X-ray diffraction analysis (2, 7, 8).

Controlling the White-Light Generation of [(RSn)4 E6 ]: Effects of Substituent and Chalcogenide Variation

Adamantane-type organotin chalcogenide clusters of the general composition [(RT)4 S6 ] (R=aromatic substituent, T=Si, Ge, Sn) have extreme non-linear optical properties that lead to highly directional white-light generation (WLG) upon irradiation with an IR laser diode. However, the mechanism is not yet understood. Now, a series of compounds [(RSn)4 E6 ] (R=phenyl, cyclopentadienyl, cyclohexyl, benzyl, CH2 CH2 (C6 H4 )CO2 Et; E=S, Se), were prepared, characterized, and investigated for their nonlinear optical properties. With the exception of crystalline [(BnSn)4 S6 ], all these compounds exhibit WLG with similar emission spectra; slight blue-shifts are observed by introduction of cyclopentadienyl substituents, while the introduction of Se in the inorganic core can provoke a red-shift. These investigations disprove the initial assumption of an aromatic substituent being a necessary precondition; the precondition seems to be the presence of (cyclic) substituents providing enough electron density.

Synthesis and Characterization of a Rare Transition-Metal Oxothiostannate and Investigation of Its Photocatalytic Properties

The new transition-metal oxothiostannate [Ni(cyclen)(H₂O)₂]₄[Sn₁₀S₂₀O₄]·∼13H₂O (1) was prepared under hydrothermal conditions using Na₄SnS₄·14H₂O as the precursor in the presence of [Ni(cyclen)(H₂O)₂](ClO₄)₂·H₂O. Compound 1 comprises the [Sn₁₀S₂₀O₄]^8- anion constructed by the T3-type supertetrahedron [Sn₁₀S₂₀] and the [Sn₁₀O₄] anti-T2 cluster. Channels host the H₂O molecules, and the sample can be reversibly dehydrated and rehydrated without significantly affecting the crystallinity of the material. ¹¹⁹Sn NMR spectroscopy of an aqueous solution of Na₄SnS₄·14H₂O evidences that between 25 and 120 °C only [SnS₄]^4- and [Sn₂S₆]^4- anions are present. In further experiments, hints were found that the formation of tin oxosulfide ions depends on the Ni²⁺-centered complexes. Compound 1 exhibits promising photocatalytic properties for the visible-light-driven hydrogen evolution reaction, with 18.7 mmol·g^-1 H₂ being evolved after 3 h.

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.

Ternary Mixed-Valence Organotin Copper Selenide Clusters

Reactions of the organotin selenide chloride clusters [(R¹ Sn^IV )₃ Se₄ Cl] (A, R¹ =CMe₂ CH₂ C(O)Me) or [(R¹ Sn^IV )₄ Se₆ ] (B) with [Cu(PPh₃ )_3-x Cl_x ] yield cluster compounds with different inorganic, mixed-valence core structures: [Cu₄ Sn^II Sn^IV₆ Se₁₂ ], [Cu₂ Sn^II₂ Sn^IV₄ Se₈ Cl₂ ], [Cu₂ Sn^II Sn^IV₄ Se₈ ], [Cu₂ Sn^II₂ Sn^IV₂ Se₄ Cl₄ ], and [Cu₂ Sn^IV₂ Se₄ ]. Five of the compounds, namely [(CuPPh₃ )₂ {(R¹ Sn^IV )₂ Se₄ }] (1), [(CuPPh₃ )₂ Sn^II {(R² Sn^IV )₂ Se₄ }₂ ] (2), [(CuPPh₃ )₂ (Sn^II Cl)₂ {(RSn^IV )₂ Se₄ }₂ ] (3) [(CuPPh₃ )₂ (Sn^II Cu₂ ){(R¹ Sn^IV )₂ Se₄ }₃ ] (4), and [Cu(CuPPh₃ )(Sn^II Cu₂ ){(R¹ Sn^IV )₂ Se₄ }₃ ] (5) are structurally closely related. They are based on [(CuPPh₃ )₂ {(RSn^IV )₂ Se₄ }_n ] aggregates comprising [(RSn^IV )₂ Se₄ ] and [CuPPh₃ ] building units, which are linked by further metal atoms. A sixth compound, [(CuPPh₃ )₂ (Sn^II Cl)₂ {(R¹ Sn^IV Cl)Se₂ }₂ ] (6), differs from the others by containing [(RSn^IV Cl)Se₂ ] units instead, which affects the absorption properties. The compounds were analyzed by single-crystal X-ray diffraction, NMR and ¹¹⁹ Sn Mössbauer spectroscopy, DFT calculations as well as optical absorption experiments.

Room-Temperature Synthesis of Thiostannates from {[Ni(tren)]2[Sn2S6]}n

The compound {[Ni(tren)]2[Sn2S6]}n (1) (tren = tris(2-aminoethyl)amine, C6H18N4) was successfully applied as source for the room-temperature synthesis of the new thiostannates [Ni(tren)(ma)(H2O)]2[Sn2S6]·4H2O (2) (ma = methylamine, CH5N) and [Ni(tren)(1,2-dap)]2[Sn2S6]·2H2O (3) (1,2-dap = 1,2-diaminopropane, C3H10N2). The Ni-S bonds in the Ni2S2N8 bioctahedron in the structure of 1 are analyzed with density functional theory calculations demonstrating significantly differing Ni-S bond strengths. Because of this asymmetry they are easily broken in the presence of an excess of ma or 1,2-dap immediately followed by Ni-N bond formation to N donor atoms of the amine ligands thus generating [Ni(tren)(amine)](2+) complexes. The chemical reactions are fast, and compounds 2 and 3 are formed within 1 h. The synthesis concept presented here opens hitherto unknown possibilities for preparation of new thiostannates.

Organotin-oxido cluster-based multiferrocenyl complexes obtained by hydrolysis of ferrocenyl-functionalized organotin chlorides

Three organotin-oxido clusters were formed by hydrolysis of ferrocenyl-functionalized organotin chloride precursors in the presence of NaEPh (E=S, Se). [R(Fc) SnCl3 ⋅HCl] (C; R(Fc) = CMe2 CH2 C(Me)=N-N=C(Me)Fc) and [SnCl6 ](2-) formed {(R(Fc) SnCl2 )3 [Sn(OH)6 ]}[SnCl3 ] (3 a) and {(R(Fc) SnCl2 )3 [Sn(OH)6 ]}[PhSeO3 ] (3 b), bearing an unprecedented [Sn4 O6 ] unit, in a one-pot synthesis or stepwise through [(R(Fc) SnCl2 )2 Se] (1) plus [(R(Fc) SnCl2 )SePh] (2). A one-pot reaction starting out from FcSnCl3 gave [(FcSn)9 (OH)6 O8 Cl5 ] (4), which represents the largest Fc-decorated Sn/O cluster reported to date.

Synthesis, crystal structure, and photoluminescence studies of a ruthenocenyl-decorated Sn/S cluster

Recently, we reported on ferrocenyl-decorated Sn/S clusters; herein, we present the extension of our investigations by attachment of ruthenocenyl units to an according cluster skeleton. The latter was realized upon improvement of the synthesis of acetylruthenocene, its conversion to a hydrazone derivative, and the subsequent reaction with a keto-functionalized Sn/S precursor complex. The report comprises the crystal structures of acetylruthenocene and the ruthenocenyl-terminated Sn/S cluster [(R(Rc)Sn)4Sn2S10] (R(Rc) = CMe2CH2C(Me)═N-N═C(Me)Rc), as well as the discussion of the electrochemical properties of the latter and its behavior during time-resolved photoluminescence investigations.

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.

[XIm][FeI(CO)3(SnI3)2] (XIm: EMIm, EHIm, PMIm) containing a barbell-shaped FeSn2-carbonyl complex

By reacting Fe(CO)(5) and SnI(4) in the ionic liquids [XIm][NTf(2)] (XIm: 1-ethyl-3-methylimidazolium/EMIm, 1-ethyl-imidazolium/EHIm, 1-propyl-3-methylimidazolium/PMIm; NTf(2): bistrifluoridomethansulfonimide), the compounds [XIm][FeI(CO)(3)(SnI(3))(2)] are obtained as transparent, dark red crystals. According to single-crystal structure analysis, the title compounds crystallize monoclinically and contain the anionic carbonyl complex [FeI(CO)(3)(SnI(3))(2)](-) as well as [EMIm](+), [EHIm](+) or [PMIm](+) cations. The anionic carbonyl is composed of a Sn-Fe-Sn barbell-shaped building unit with Fe-Sn distances of 252.0(1) pm. Herein, tin is coordinated distorted tetrahedrally by iodine; iron is coordinated pseudo-octahedrally by three carbonyl ligands, one iodine atom and two tin atoms. Bonding situation and valence state are investigated in detail for [EMIm][FeI(CO)(3)(SnI(3))(2)] based on bond-lengths considerations, infrared spectroscopy, Mössbauer spectroscopy, density functional theory and DFT-based Mulliken population analysis. Hence, the formal oxidation state of the metal atoms can be concluded to Fe(±0) and Sn(3+).

Intramolecularly coordinated organotin tellurides: stable or unstable?

The step-wise oxidation of an organotin(I) compound with elemental tellurium gave a variety of unprecedented organotin tellurides containing tin atoms in the oxidation states +II and +IV.

Ylenes in the M(II)→Si(IV) (M=Si, Ge, Sn) coordination mode

The reaction of the methimazolyl (mt, i.e., 2-mercapto-1-methylimidazolide) substituted silane Si(mt)(4) with SnCl(2) and GeCl(2) in dioxane affords the paddlewheel-shaped complexes [ClSi(μ-mt)(4)MCl] (M=Sn (1) and Ge (2), respectively). These compounds represent the first crystallographically characterized hexacoordinate silicon complexes comprising a Sn or Ge atom in the Si coordination sphere. An attempt to synthesize the related silicon compound 3 [ClSi(μ-mt)(4)SiCl] instead afforded the trisilane [ClSi(μ-mt)(4)Si-SiCl(3)] (3a), which provides the first crystallographic evidence for the feasibility of oligosilanes with adjacent hexacoordinate Si atoms. One of the hexacoordinate Si atoms of 3a features the unprecedented (Si(2)S(4))Si skeleton. Natural bonding orbital (NBO) analyses of compounds 1, 2, 3a (and the target compound 3) revealed characteristics of M(II)→Si(IV) (for 2 and 3) or M(I)→Si(IV) (for 3a) dative bonding in the systems with M=Si and Ge, whereas compound 1 exhibits a covalent Sn(III)-Si(III) bond.