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A series of cyclopentadienyllanthanum complexes with the disilylated metalloid germanium cluster [Ge9(Hyp)2]2–[Hyp = Si(SiMe3)3] has been prepared and fully characterized. The synthetic procedure is based on the salt metathesis reaction of two different cyclopentadienyllanthanum diiodides CpLaI2(Cp: Cp*, pentamethylcyclopentadienyl; Cpttt, 1,2,4-tri-tert-butylcyclopentadienyl) with K2[Ge9(Hyp)2] in tetrahydrofuran (THF) with a subsequent extraction with n-hexane. The composition of the obtained compounds and the mode of coordination of the germanium cluster to the rare-earth metal are strongly influenced by the steric demand of the cyclopentadienyl ligands and the crystallization conditions. The centrosymmetric dimeric compounds with the common formula [CpLa(solv)(η2,3-Ge9(Hyp)2)]2[1, Cp = Cp*, solv–THF; 2, Cp = Cpttt, solv–NCCH2C(Me)NSiMe3] have been isolated by the slow evaporation of a n-hexane solution, while a mononuclear complex [CptttLa(THF)2(η3-Ge9(Hyp)2)] (4) was found by crystallization from THF. The repeated recrystallization of 1from n-hexane afforded the asymmetric dimer [Cp*La(THF)(η2,3-Ge9(Hyp)2)][Cp*La(η2,3-Ge9(Hyp)2)] (3) with only one coordinated THF molecule.

We present the synthesis of alkyl-substituted germylenes GeFlu2, Ge(FluTMS)2, and FluTMSGeCl (Flu = 9H-fluorenyl, FluTMS= 9-trimethylsilyl-9H-fluorenyl) using bulky fluorenyl ring systems and modifications of that. GeFlu2can only be crystallized as its three-membered ring trimer, whereby the reaction is accompanied by the formation of several byproducts, such as [Li(THF)4][Ge(Ge3Flu7H)]. These results led to the modification of the fluorenyl framework by substitution the one H atom in the 9-position by a TMS group. With the synthesis of the corresponding Li salt LiFluTMS, Ge(FluTMS)2could be isolated in good yields in a further reaction. The homoleptic Ge(FluTMS)2is found in its crystalline form as a monomer and thus belongs to the series of monomeric alkyl-substituted germylenes. Also, the corresponding monoalkyl-substituted halogenido germylene was isolated as a four-membered ring tetramer [FluTMSGeCl]4during an unselective reaction. However, FluTMSGeCl undergoes significant stabilization through the formation of the monomeric phosphane adduct FluTMSGeCl·PEt3, which greatly increases the selectivity of the reaction. During further reactions of Ge(FluTMS)2with a GeBr solution (toluol/nPr3P), more impressions of the reactivity of Ge(I)X solutions with germylenes were achieved, showing that those germylenes take part in the disproportionation reaction of metastable Ge(I) solutions to give oxidized Ge(IV) compounds like (FluTMS)2GeBr2.

We report the synthesis of three neutral complexes with different coordination modes of a di-silylated metalloid germanium cluster to divalent lanthanides [(thf)5Ln(ηn-Ge9(Hyp)2)] (Ln = Yb (1, n= 1); Eu (2, n= 2, 3), Sm (3, n= 2, 3); Hyp = Si(SiMe3)3) by the salt metathesis of LnI2with K2[Ge9(Hyp)2] in THF. The complexes were characterized by elemental analysis, nuclear magnetic resonance and UV–vis–NIR spectroscopy, and single-crystal X-ray diffraction. In thf solution, the formation of contact or solvate-separated ion pairs depending on the concentration is assumed. Compound 2exhibits a blue luminescence typical for Eu2+. The solid-state magnetic measurements of compounds 2and 3confirm the presence of divalent europium and samarium, respectively.

We report the reactions of K2[Ge9(Hyp)2] (Hyp = Si(SiMe3)3) with (thf)3YbI3, ThI4, and UCl4, leading to the oxidative coupling of the metalloid germanium cluster to form the dimeric dianion [Ge18(Hyp)4]2–. The novel dimerized Ge18-cluster was isolated and characterized by single-crystal X-ray diffraction analysis as a component of ionic compounds [Yb(thf)6][Ge18(Hyp)4] (1) and [K(2.2.2-crypt)]2[Ge18(Hyp)4] (2) with two different counterions. The dihedral angle between two intact Ge9cages depends on the counterions, which was also studied by quantum-chemical calculations.

The oxidation of K[Ge9(Hyp)3] (Hyp = Si(SiMe3)3) with lanthanide triiodides LnI3(Ln = Eu, Sm, Yb) leads to the formation of novel clusters with a Ge18-core isolated as a co-crystallizate of Ge*18(Hyp)6(1a) and Ge18(Hyp)5(Si(SiMe3)2)(SiMe3) (1b). Clusters 1aand 1bdiffer distinctly from the known cluster Ge18(Hyp)6(A), which has been found earlier in the reaction of K[Ge9(Hyp)3] with FeCl2and now identified as an intermediate product in the production of compounds 1aand 1b. These three compounds A, 1a, and 1bare thus structural isomers being the first example of genuine isomerism in metalloid main-group cluster compounds.

The isolation of the germanium mixed halide cluster Ge14Br8–xClx(PEt3)4(2) by the reaction of a metastable GeIBr solution (toluene/PEt3) with GeCl2·dioxane provides new insights into the complex formation mechanism of metalloid germanium clusters through the disproportionation reaction of GeIX (X = Cl and Br). It is shown that the GeIIhalide is involved in at least two steps in the build-up reaction of 2. The molecular structure of 2is presented together with a plausible reaction mechanism leading to the binary cluster Ge14Br8(PEt3)4and future aspects of these findings.

The reaction of GeCl2·dioxane with 2 equiv of the thiolate LiSHyp [Hyp = Si(SiMe3)3] yields the germanide (12-crown-4)2Li[Ge(SHyp)3] (1). A small structural variation in the substituent leads to a completely different result because the reaction of GeCl2·dioxane with 2 equiv of the thiolate KSHypPh3[HypPh3= Si(SiMe3)2(SiPh3)] in toluene yields the unexpected compound [Ph3Si][Me3Si]Ge[{(C6H5)Ph2Si}{SiMe3}2SiS]Si[SSiMe3] (2) in high yield. The reaction cascade to give 2includes several rearrangement reactions and an intramolecular [2 + 4] cycloaddition of a phenyl ring. The syntheses and molecular structures of both compounds are presented, together with quantum-chemical calculations and NMR measurements, to enlighten the reaction mechanism behind the formation of 2.

The reaction of [(Hyp)2Ge9]2–(Hyp = Si(SiMe3)3) with ClSiMe2-C6H4-SiMe2Cl gives [K(THF)][(Hyp)2Ge9-SiMe2-C6H4-SiMe2-Ge9(Hyp)2K] K1in 45% yield in the form of orange-red crystals. 1is thereby the first compound where two Ge9(Hyp)2clusters are bound together via a bridging ligand. 1is stable in solution but cannot be transferred intact into the gas phase via electrospray ionization indicating a higher reactivity with respect to other metalloid Ge9R3clusters. The arrangement of the nine germanium atoms within the two Ge9units in 1is unique for metalloid Ge9R3clusters. Quantum chemical calculations further reveal an electronic interaction of the two Ge9units in 1via the bridging phenylene group.

There is increased evidence that the effect of bulky groups in organic, organometallic, and inorganic chemistry is not only repulsive but can be attractive because of London dispersion interactions. The influence of the size of primary alkyl substituents in 2- and 2,3-positions of anthracenes on the diastereoselectivity (anti vs syn dimer) of the [π4s+ π4s] photoinduced dimerization is investigated. The synthesis of the anthracene derivatives was achieved by Suzuki–Miyaura reaction of 2,3-dibromoanthracene with alkylboronic acids as well as by reduction of anthraquinones that were obtained from 2,3-disubstituted 1,3-butadienes and naphthoquinone followed by dehydrogenation. The mixtures of dianthracene isomers were analyzed with respect to the anti/syn-ratio of the products by X-ray crystallography and nuclear Overhauser effect spectroscopy. While for the 2,3-dimethylanthracene the anti and syn isomers were formed in equal amounts, the anti dimers are the major products in all other cases. A linear correlation (R2= 0.98) between the steric size (Charton parameter) and the isomeric ratio suggests that the selectivity is dominated by classical repulsive steric effects. An exception is the iso-butyl substituent that produces an increased amount of the syn isomer. It is suggested that this is due to an exalted effect of London dispersion interactions.

The disproportionation reaction of the subvalent metastable halide SnBr proved to be a powerful synthetic method for the synthesis of metalloid cluster compounds of tin. Hence the neutral metalloid cluster compound Sn10[Si(SiMe3)3]6(1) was synthesized from a reaction of a SnBr emulsion with LiSi(SiMe3)3. Using the phosphane PnBu3as a donor component during the synthesis of the monohalide solution, an isolable SnIhalide solution is obtained. The reaction of such an isolable SnCl solution with LiSi(SiMe3)3gives the anionic metalloid cluster compound {Sn10[Si(SiMe3)3]5}–(5) in 63 % yield, where only five tin atoms are bound to one ligand and where a centaur polyhedral arrangement of the ten tin atoms is present. Due to the open structure 5might be used for further applications in the field of subsequent build‐up reactions.

A small leak will sink a great ship: Treating SnIBr with LiSi(SiMe3)3gives the polyhedral title cluster, a new member of the singlet biradicaloid species. Calculations show that the ligand orientation influences the bonding inside the cluster leading to a sudden transition between bonded and biradicaloid forms. The cluster could be an ideal model system to study this transition.

Kleine Ursache, große Wirkung: Die Umsetzung von SnIBr mit LiSi(SiMe3)3ergibt die Titelverbindung, ein neues Mitglied der Singulett‐Biradikaloide. Rechnungen zeigen, dass die Ligandenanordnung die Bindungssituation im Clusterkern beeinflusst und zu einem scharfen Übergang annähernd erster Ordnung zwischen gebundener und biradikaloider Form führt. Der Cluster könnte eine ideale Modellsubstanz für diesen Übergang sein.

Thermodynamic data for gaseous SnBr, derived from quantum chemical (MP2)‐calculations show that this monohalide should be formed at 1370 °C as a product of the reaction of elemental tin with HBr at 1 × 10–2mbar. Applying the cocondensation technique, SnBr can be trapped at –196 °C and prepared in synthetic scale. Herein first analysis of SnBr are presented, showing that SnBr is more reactive than the corresponding GeBr, already disproportionating quantitatively to elemental tin and SnBr2on heating to room temperature. 119Sn Mössbauer spectroscopic measurements confirm the disproportionation by showing three single signals in the spectra which can be attributed to elemental tin, SnBr2and a trace amount of SnO2.

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