Coordination chemistry of organometallic or inorganic binary group 14/16 units towards d-block and f-block metal atoms

An Organometallic Erbium Bismuth Cluster Complex Comprising a Bi66- Zintl Ion

An organometallic erbium bismuth cluster complex, [K(THF)4]2[Cp*2Er2Bi6] (1), featuring a heterometallocubane core was isolated. The cube emerges from the rare Bi66- Zintl ion, bridging two erbium centers for the first time. SQUID magnetometry and ab initio calculations uncovered dominant antiferromagnetic coupling enabled through the chair-like hexabismuth anion. The gained insight will promote the design of future polynuclear magnetic molecules comprising prolate lanthanide ions.

Dimers and 2D Networks of Adamantane-Related Ternary Organosilicon Coinage Metal Sulfide Clusters

Adamantane-type organotin sulfide clusters were recently shown to react with coinage metal phosphine complexes under replacement of an organic substituent by a metal-phosphine unit. An extension of such studies involving the silicon-based congener [(PhSi)4S6] (A) revealed that the cluster core will be partly disassembled and a {PhSi} moiety is replaced by a coinage metal phosphine complex to form [(Et3PAg)3(PhSi)3S6] (B) and [Na2(thf)2.33][(Me3PCu)(PhSi)3S6] (C). Herein, we present an extension of this work upon variation of the reactants and reaction conditions. Besides the isolation of crystalline precursor complexes [CuCl(PMe2Ph)3] (1) and [AgCl(PMe2Ph)2]2 (2), the study addresses reactions of A with AgCl and a phosphine ligand in CH2Cl2, upon which A is completely disassembled to form [(Ph3P)3Ag(μ-S)SiCl2Ph] (3). In another case a CH2 group, most likely stemming from CH2Cl2, was attached to the ligand, thus generating [{PhCl(S)SiSCH2P(Ph2)CH2CH2}2] (4). Upon using CuCl and 1,4-bis(diphenylphosphino)butane (dppb) we isolated the phosphine-bridged analog of B, [{(dppbCu2)CuP(Ph2)(CH2CH2)(PhSi)3S6}2] (5). In order to receive the yet elusive silver homolog of C, we used PMe2Ph as a bulkier ligand. This way we generated a 2D coordination polymer of the desired composition, [Na2(thf)1.5][(Me2PhPAg)(PhSi)3S6] (6). UV-visible spectra of 6 indicated a bandgap of 3.89 eV, thus blue-shifted in regards to B and C.

Pseudotetrahedral Organotin-Capped Chalcogenidometalate Supermolecules with Optical Limiting Performance

The rational design of crystalline clusters with adjustable compositions and dimensions is highly sought after but quite challenging as it is important to understand their structural evolution processes and to systematically establish structure-property relationships. Herein, a family of organotin-based sulfidometalate supertetrahedral clusters has been prepared via mixed metal and organotin strategies at low temperatures (60-120 °C). By engineering the metal composition, we can effectively control the size of the clusters, which ranges from 8 to 35, accompanied by variable configurations: P1-[(RSn)4M4S13], T3-[(RSn)4In4M2S16] (R = nbutyl-Bu and phenyl-Ph; M = Cd, Zn, and Mn), T4-[(BuSn)4In13Cu3S31], truncated P2, viz. TP2-[(BuSn)6In10Cu6S31], and even T5-[(BuSn)4In22Zn6Cu3S52], all of which are the largest organometallic supertetrahedral clusters known to date. Of note, the arylstannane approach plays a critical role in regulating the peripheral ligands and further enriching geometric structures of the supertetrahedral clusters. This is demonstrated by the formation of tin-oxysulfide clusters, such as T3-[(RSn)4Sn6O4S16] (R = Bu, Ph, and benzyl = Be) and its variants, truncated T3, viz., TT3-[(BuSn)6Sn3O4S13] and augmented T3, viz., T3-[(Bu3SnS)4Sn6O4S16]. Especially, two extraordinary truncated clusters break the tetrahedral symmetry observed in typical supertetrahedral clusters, further substantiating the advantages offered by the arylstannane approach in expanding cluster chemistry. These organometallic supertetrahedral clusters are highly soluble and stable in common solvents. Additionally, they have tunable third-order nonlinear optical behaviors by controlling the size, heterometallic combination, organic modification, and intercluster interaction.

Systematic Access of Ternary Organotetrel-Copper Chalcogenide Clusters by [PhTE3 ]3- Anions (T=Si, Sn; E=S, Se)

Fragmentation reactions of organotetrel chalcogenide heteroadamantane-type clusters [(PhT)4 E6 ] (T/E=Si/S (1); Si/Se; Sn/S, and Sn/Se) by addition of the corresponding sodium chalcogenide gave salts of the general formula Na3 [PhTE3 ], with T/E=Si/S (2); Si/Se (3); Sn/S (A); Sn/Se (4). Reaction of these salts with [Cu(PPh3 )3 Cl] gave a series of organotetrel-copper chalcogenide clusters [(CuPPh3 )6 (PhTE3 )2 ] with T/E=Si/S; (5), Si/Se (6), Sn/S (7) and Sn/Se (8). Compounds 5-8 share a common structural motif with two intact {PhTE3 } units coordinating a Cu6 moiety, which was previously reported with other ligands, and for the Sn and Ge congeners only. If the Sn/Se reaction system was allowed to crystallize more slowly, single crystals of compound [(CuPPh3 )6 (PhSnSe3 )3 Cu3 SnSe] (9) were obtained, which are based on a larger cluster structure. Hence, 9 might form from 8 through incorporation of additional cluster fragments. The experimentally and quantum chemically determined optical properties were compared to related clusters.

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.

Current advances in tin cluster chemistry

This perspective summarizes highlights and most recent advances in tin cluster chemistry, thereby addressing the whole diversity of (mostly) discrete units containing tin atoms. Although being a (semi-)metallic element, tin is in the position to occur both in formally positive or negative oxidation states in these molecules, which causes a broad range of fundamentally different properties of the corresponding compounds. Tin(iv) compounds are not as oxophilic and not as prone to hydrolysis as related Si or Ge compounds, hence allowing for easier handling and potential application. Nevertheless, their reactivity is high due to an overall reduction of bond energies, which makes tin clusters interesting candidates for functional compounds. Beside aspects that point towards bioactivity or even medical applications, materials composed of naked or ligand-protected tin clusters, with or without bridging ligands, show interesting optical, and ion/molecule-trapping properties.

Variations in the Interplay of Intermetallic and Metal Chalcogenide Units in Organotin-Copper Selenide Clusters

We report the formation and structures of two new organotin-copper selenide clusters that were obtained in a two-step procedure. First, [(R¹Sn)₄Se₆] [R¹ = CMe₂CH₂C(O)Me] is reacted with [Cu(PPh₃)₃Cl] and (SiMe₃)₂Se to form a bright-orange powder, the nature of which could not be identified in detail, yet a suspension of it in CH₂Cl₂ reacts with N₂H₄·H₂O to afford single crystals of two cluster compounds, either [(Cu₃Sn){(R²Sn)₂Se₄}₂{(R²Sn₂)Se₃}] (1) or [(N₂H₄)(Cu₄Sn){(R²Sn)₂Se₄}₃] [2; R² = CMe₂CH₂C(NNH₂)Me]. Both are based on an intermetallic Cu_xSn cluster core (x = 3, 4), which is surrounded by organotin selenide units in different fashions. The results foster the assumption of a complex equilibrium to be present in according reaction mixtures.

[{(PhSn)3SnS6}{(MCp)3S4}] (M = W, Mo): Minimal Molecular Models of the Covalent Attachment of Metal Chalcogenide Clusters on Doped Transition Metal Dichalcogenide Layers

With the aim to mimic the yet unknown covalent deposition of metal chalcogenide clusters on transition metal dichalcogenide (TMDC) MoS₂ or WS₂ layers, and thereby explore the interaction between the two systems and potential consequences on physical properties of the TMDC material, we synthesized heterobimetallic model systems. The heterocubane-type cluster [(SnCl₃)(WCp)₃S₄] (1), the organotin-sulfidomolybdate cluster [{(PhSn)₃SnS₆}{(MoCp)₃S₄}] (2), and the corresponding tungstate [(PhSn)₃SnS₆{(WCp)₃S₄}] (3) were obtained in ligand exchange reactions from [(PhSn)₄S₆] and [M(CO)₃CpCl]. Indeed, the {M₃S₄} cages in 1-3 resemble a section of the respective TMDC monolayers, altogether representing minimal molecular model systems for the adsorption of organotin sulfide clusters on MoS₂ or WS₂. The interaction between the {(MCp)₃S₄} and {(PhSn)₃SnS₆} subunits is characterized by multicenter bonding, rendering the respective Sn atom as Sn(II), hence driving the clusters into a mixed-valence Sn(IV)/Sn(II) situation, and the M atoms as M(IV) upon an in situ redox process. The attachment is thus weaker than via regular covalent M-S bonds, but definitely stronger than via van der Waals interactions that have been characteristic for all known interactions of clusters on TMDC surfaces so far. Computational analyses of an extended model mimicking the electronic situation in the cluster prove the analogy to a covalent attachment on TMDCs.

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.