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The microwave-assisted polyol process was applied to synthesize phase-pure micro- or nanocrystalline samples of intermetallic phases in the systems T-M (with T = Co, Ni, Rh, Pd, Ir, Pt and M = Sn, Sb, Pb, Bi). Reaction temperatures range between 240 °C and 300 °C and reaction times of a few minutes up to one hour are sufficient. For the optimization of the syntheses reaction temperature, reaction time, and metal precursors were changed. To obtain phase-pure samples the process was further modified by the addition of potassium hydroxide, oleylamine, or oleic acid. Single-phase powders of a variety of intermetallic compounds were synthesized. Although not stable at the temperature of synthesis, high-temperature phases are accessible as well. The microwave-assisted polyol process opens up the possibility to synthesize intermetallic compounds in a fast and easily applicable one-step route, without the utilization of strong and often toxic reducing agents.

A new heteroleptic cationic copper(I) complex bearing two N-heterocyclic carbene (NHC) ligands has been prepared. In situ, a Cu–O-bond can be generated which enables the complex to catalytically activate H2. The resulting complex shows activity in catalytic chemo- and stereoselective alkyne semihydrogenations as well as conjugate reductions of enones.

A simple and air-stable copper(I)/N-heterocyclic carbene complex enables the catalytic hydrogenation of hitherto unreactive enoates and enamides employing H2 as terminal reducing agent. This atom economic transformation replaces commonly employed hydrosilanes and can also be carried out in an asymmetric fashion.

The mechanisms of the polyol reduction of copper(ii) compounds were investigated by various systematic experiments. The course of the reduction in ethylene glycol strongly depends on the anion present in solution. Elemental copper can only be obtained in high yields starting from Cu(NO3)2, Cu(OAc)2, or Cu(OH)2; but not from CuCl2 or CuSO4. Intermediate compounds were observed, namely Cu2O, and the alkoxide compounds Cu(C2H4O2) and Cu3(OAc)2(C2H4O2)2. Cu3(OAc)2(C2H4O2)2 was characterised by single-crystal X-ray diffraction. It is a 2D coordination polymer with bridging bidentate acetate and bidentate deprotonated EG ligands leading to vertex- and edge-linked CuO5 polyhedra. Alkoxide compounds were also detected for higher glycol ethers. With growing glycol ether chain length the stability of alkoxide intermediates decreases, enhancing the stability range of Cu2O. Because the majority of copper species is precipitated as copper(ii) alkoxide compounds or Cu2O before the reduction to elemental copper occurs, only few nuclei are formed in solution leading to microparticles instead of nanoparticles. Much smaller but strongly agglomerated particles were observed under alkaline reaction conditions.

Halogen substitution, that is, bromine for iodine, in the series of topological BinTeI (n = 1, 2, 3) materials was conducted in order to explore the impact of anion exchange on topological electronic structure. In this proof-of-concept study, we demonstrate the applicability of the modular view on crystal and electronic structures of new Bi2TeBr and Bi3TeBr compounds. Along with the isostructural telluroiodides, they constitute a family of layered structures that are stacked from two basic building modules, ∞2[Bi2] and ∞2[BiTeX] (X = I, Br). We present solid-state synthesis, thermochemical studies, crystal growth, and crystal-structure elucidation of Bi2TeBr [space group R3̅m (no. 166), a = 433.04(2) pm, c = 5081.6(3) pm] and Bi3TeBr [space group R3m (no. 160), a = 437.68(3) pm, c = 3122.9(3) pm]. First-principles calculations establish the topological nature of Bi2TeBr and Bi3TeBr. General aspects of chemical bonding appear to be similar for BinTeX (X = I, Br) with the same n, so that alternation of the global gap size upon substitution is insignificant. The complex topological inversion proceeds between the states of two distinct modules, ∞2[Bi2] and ∞2[BiTeBr]; thus, the title compounds can be seen as heterostructures built via a modular principle. Furthermore, highly disordered as well as incommensurately modulated ternary phase(s) are documented near the Bi2TeBr composition. Single-crystal X-ray diffraction experiments on BiTeBr and Bi2TeI resolve some discrepancies in prior published work., This work was supported by the German Research Foundation (DFG) in the framework of the Special Priority Program (SPP 1666) Topological Insulators and by the ERANET-Chemistry Program. We acknowledge support by Academic D. I. Mendeleev Fund Program of Tomsk State University (Project 8.1.01.2018), by St. Petersburg State University (Project 15.61.202.2015), by Ministry of Education and Science of the Russian Federation within the framework of the governmental program Megagrants (State Task 3.8716.2017/P220 or 3.8716.2017/9.10), by Russian Science Foundation 18-12-00169 (for surface electronic structure within tight-binding method), by Spanish Ministry of Science and Innovation (Grants FIS 2013-48286-C02-02-P, FIS 2013-48286-C02-440-01-P, and FIS 2016-75862-P).