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The regioselective synthesis of germasila-adamantanes with the germanium atoms in the bridgehead positions is described starting from cyclic precursors by a cationic sila-Wagner-Meerwein (SWM) rearrangement reaction. The SWM rearrangement allows also a deliberate shift of germanium atoms from the periphery and within the cage structures into the bridgehead positions. This opens the possibility for a synthesis of germasila-adamantanes of defined germanium content and controlled regiochemistry. In the same way that sila-adamantane can be regarded as a molecular building block of elemental silicon, the germasila-adamantane molecules represent cutouts of silicon/germanium alloys., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The mixed heteroadamantanes Si 6 Ge 4 and Si 6 Sn 4 are readily accessible from Me 2 ECl 2 /Si 2 Cl 6 /cat. Cl - (4 × EMe 2 , 2 × SiCl 2 , 4 × Si-SiCl 3 vertices; E = Ge, Sn). Different from Si 6 Ge 4 , two skeletal isomers are formed in the case of Si 6 Sn 4 . Site-selective SiCl 3 -methylation of Si 6 Ge 4 was achieved, leaving the SiCl 2 groups untouched.

Si 1- x Ge x nanowires (NWs) were prepared by gold-supported chemical vapor deposition (CVD) using a single-source precursor with preformed Si-Ge bonds. Besides the tamed reactivity of the precursor, the approach reduces the process parameters associated with the control of decomposition characteristics and the dosing of individual precursors. The group IV alloy NWs are single crystalline with a constant diameter along their axis. During the wire growth by low pressure CVD, an Au-containing surface layer on the NWs forms by surface diffusion from the substrate, which can be removed by a combination of oxidation and etching. The electrical properties of the Si 1- x Ge x /Au core-shell NWs are compared to the Si 1- x Ge x NWs after Au removal. Core-shell NWs show signatures of metal-like behavior, while the purely semiconducting NWs reveal typical signatures of intrinsic Si 1- x Ge x . The synthesized materials should be of high interest for applications in nano- and quantum-electronics.

The Cl - diadduct [ n Bu 4 N] 2 [A·2Cl] of the mixed cyclohexatetrelane (SiCl 2 ) 5 (GeMe 2 ), A, is accessible from Me 2 GeCl 2 , 6 eq. Si 2 Cl 6 , and 2 eq. [ n Bu 4 N]Cl in one step (96%). Free, tenfold functionalized A can be released from the primary product by decomplexation with AlCl 3 (78%). Insight into the assembly mechanism of [ n Bu 4 N] 2 [A·2Cl] and the reactivity of A is provided.

A series of new mixed-substituted heteronuclear precursors with preformed Si-Ge bonds has been synthesized via a two-step synthesis protocol. The molecular sources combine convenient handling with sufficient thermal lability to provide access to group IV alloys with low carbon content. Differences in the molecule-material conversion by chemical vapor deposition (CVD) techniques are described and traced back to the molecular design. This study illustrates the possibility of tailoring the physical and chemical properties of single-source precursors for their application in the CVD of Si 1- x Ge x coatings. Moreover, partial crystallization of the Si 1- x Ge x has been achieved by Ga metal-supported CVD growth, which demonstrated the potential of the presented precursor class for the synthesis of crystalline group IV alloys.

Si x Ge y alloys are emerging materials for modern semiconductor technology. Well-defined model systems of the bulk structures aid in understanding their intrinsic characteristics. Three such model clusters have now been realized in the form of the Si x Ge y heteroadamantanes [0], [1], and [2] through selective one-pot syntheses starting from Me 2 GeCl 2 , Si 2 Cl 6 , and [nBu 4 N]Cl. Compound [0] contains six GeMe 2 and four SiSiCl 3 vertices, whereas one and two of the GeMe 2 groups are replaced by SiCl 2 moieties in compounds [1] and [2], respectively. Chloride-ion-mediated rearrangement quantitatively converts [2] into [1] at room temperature and finally into [0] at 60 °C, which is not only remarkable in view of the rigidity of these cage structures but also sheds light on the assembly mechanism., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Treatment of Si 2 Cl 6 with [Et 4 N][BCl 4 ] in CH 2 Cl 2 furnished the known products of a chloride-induced disproportionation reaction of the disilane, such as SiCl 4 , [Si(SiCl 3 ) 3 ] - , and [Si 6 Cl 12 ·2Cl] 2- . No Si-B-bonded products were detectable. In contrast, the addition of Si 2 Cl 6 to [Et 4 N][BI 3 Cl] afforded the Si-B adduct [Et 4 N][I 3 SiBI 3 ]. Thus, a quantitative Cl/I exchange at the silicon atom accompanies the trihalogenosilanide formation. [Et 4 N][I 3 SiBI 3 ] was also accessible from a mixture of Si 2 I 6 , [Et 4 N]I, and BI 3 . According to X-ray crystallography, the anion [I 3 SiBI 3 ] - adopts a staggered conformation with an Si-B bond length of 1.977(6) Å. Quantum-chemical calculations revealed a polar covalent Si-B bond with significant contributions from intramolecular I···I dispersion interactions.