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In situ prepared lithium arylselenolates {LiSePh, LiSe(2,6-Me2Ph), LiSe(2,4,6-Me3Ph)} or -tellurolates {LiTePh, LiTe(2,6-Me2Ph), LiTe(2,4,6-Me3Ph)} react with [ReOCl3(PPh3)2] and (NBu4)Br in good yields under formation of rhenium(V) complexes of the composition (NBu4)[ReO(L)4)]. The first oxidorhenium(V) complex with four monodentate phenolato ligands, [ReO(2,6-Me2Ph)4]−, was prepared and isolated in crystalline form. This allows a comparison of experimental and computational data of a full series of such compounds with basal O, S, Se and Te donor atoms. Similar reactions with [ReCl3(PPh3)2(CH3CN)] or [ReCl3(PMe2Ph)3] give trigonal bipyramidal rhenium(III) complexes of the compositions [Re(PPh3)(L)3(CH3CN)] or [Re(PPh3)2(L)3] depending on the chalcogenolate applied. The reported oxidorhenium(V) and rhenium(III) complexes were fully characterized by spectroscopic methods and X-ray diffraction. The bonding situation in the rhenium(V) and rhenium(III) chalcogenolates was assessed through density functional theory calculations based on the quantum theory of atoms in molecules (QTAIM), natural bonding orbital (NBO) analysis, charge analysis, the electron localization function (ELF) maps and topological descriptors at the {3,−1} critical points such as metallicities. Expectedly, the ionicity of the rhenium-chalcogen bonds decreases according to all three applied charge models from O to Te. Generally, the Re−Se and Re−Te bonds are more directional in the Re(III) complexes than in the oxidorhenium(V) compounds.

The first crystalline technetium complex in a negative oxidation state, [Tc−I(CO)(CNp-F-ArDArF2)4]−, was isolated and structurally characterized as its [Na(Crypt-2.2.2)]+ salt. It mirrors the properties of the textbook organometallic compound Na[Tc(CO)5], which has eluded isolation and structural characterization until today. [Na(Crypt-2.2.2)][Tc−I(CO)(CNp-F-ArDArF2)4] reacts expectedly as a nucleophile, which is demonstrated by reactions with HCl and ClSnMe3. They give the unprecedented monohydrido and trimethylstannyl complexes of technetium.

Reactions of [Re(NPhF)Cl3(PPh3)2] ({NPhF}2− = p-fluorophenylimide) with a variety of alkyl and aryl isocyanides have been studied. Different reactivity patterns and products have been obtained depending on the steric and electronic properties of the individual ligands. This involves the formation of 1 : 1 and 1 : 2 exchange products of Re(V) with the general formulae mer-[Re(NPhF)Cl3(PPh3)(isocyanide)] and cis- or trans-[Re(NPhF)Cl3(isocyanide)2]. The stability of the obtained products is correlated with the substitution pattern of the isocyanide ligands. The products have been studied by single-crystal X-ray diffraction and spectroscopic methods, including IR and multinuclear NMR spectroscopy as well as mass spectrometry. The use of partially fluorinated starting materials and ligands allows the modulation of the solubilities of the starting materials and the products as well as the monitoring of the reactions by means of 19F NMR. The attachment of the CF3 or F substituent on the isocyanides gives control over the steric bulk and the electronic properties of the ligands and, thus, their reactivity.

Zwitterionic compounds such as pyridine-containing tellurenyl compounds are interesting building blocks for heterometallic assemblies. They can act as ambiphilic donor/acceptors as is shown by the products of reactions of the zwitterions HpyTeCl2 or HCF3pyTeCl2 with the rhenium(V) complex [ReOCl3(PPh3)2]. The products have a composition of [ReO2Cl(pyTeCl)(PPh3)2] and [ReO2Cl(CF3pyTeCl)(PPh3)2] with central {O=Re=O…Te(Cl)p⏠y}+ units. The Re-O bonds in the products are elongated by approximately 0.1 Å compared with those to the terminal oxido ligands and establish Te…O contacts. Thus, the normally easily assigned concept of oxidation states established at the two metal ions becomes questionable (ReV/TeII vs. ReIII/TeIV). A simple bond length consideration rather leads to a description with the coordination of a mesityltellurenyl(II) chloride unit to an oxido ligand of the Re(V) center, but the oxidation of the tellurium ion and the formation of a tellurinic acid chloride cannot be ruled out completely from an analysis of the solid-state structures. DFT calculations (QTAIM, NBO analysis) give clear support for the formation of a Re(V) dioxide complex donating into an organotellurium(II) chloride and the alternative description can at most be regarded as a less favored resonance structure.

The first consistent series of mononuclear 17-electron complexes of three Group 7 elements has been isolated in crystalline form and studied by X-ray diffraction and spectroscopic methods. The paramagnetic compounds have a composition of [M0(CO)(CNp-F-ArDarF2)4] (M = Mn (1), Tc (3), Re (6); ArDArF2 = 2,6-(3,5-(CF3)2C6H3)2­C6H3)) and are stabilized by four sterically encumbering isocyanides, which prevent the metalloradicals from dimerization. They have a square pyramidal structure with the carbonyl ligands as apexes. The frozen-solution EPR spectra of the rhenium and technetium compounds are clearly anisotropic with large 99Tc and 185,187Re hyperfine interactions for one component. High-field EPR (Q band and W band) has been applied for the elucidation of the EPR parameters of the manganese(0) complex.

Phenyltelluroxane clusters of the composition [{(PhTe)19O24}2I18(solv)] (1) are formed during the hydrolysis of [PhTeI3]2 or the oxidation of various phenyltellurium(II) compounds with iodine under hydrolytic conditions. The compounds consist of two half‐spheres with a {(PhTe)19O24}9+ network, which are connected by 18 iodine atoms. The spherical clusters can accommodate solvent molecules such as pyridine or methanol in the center of two rings formed by iodine atoms. The presence of other metal ions during the cluster formation results in a selective replacement of the central {PhTe}3+ units of each half‐sphere as has been demonstrated with the isolation of [{(PhTe)18({Ca(H2O)2}O24}2I16] (2) and [{(PhTe)18({Y(NO3)(H2O)}O24}2I16] (3). A crownether‐like coordination by six oxygen atoms of the telluroxane network is found for the {Ca(H2O}2}2+ and {Y(NO3)(H2O)}2+ building blocks. Mass spectrometric studies show that considerable amounts of the intact clusters are transferred to the gas phase without dissociation., Large telluroxane clusters are formed during the hydrolysis of [PhTeI3]2 or the oxidation of [PhTe]2 with iodine under hydrolytic conditions. They consist of two half‐spheres with {(PhTe)19O24}9+ networks, which are connected by 18 iodine atoms. The central {PhTe}3+ units of each half‐sphere can be replaced by other metal ions. Mass spectrometry shows that the intact clusters are transferred to the gas phase without dissociation.

Potentially tridentate, phosphine-containing Schiff bases with P,N,O and P,N,P donor sets have been prepared from 2-(diphenylphosphino)benzaldehyde, salicylaldehyde, 2-aminophenol and 2-((diphenylphosphino)phenyl)methylamine and reacted with (NEt4)(2)[Re(CO)(3)Br-3] in methanol. Deprotonation and the formation of neutral [Re(CO)(3)(L)] complexes with tridentate coordination of the Schiff bases has been obtained for the salicylidene derivatives, while the potential P,N,P ligand L-3 forms [Re(CO)(3)Br(L-3)] with the Schiff base in a bidentate bonding mode. The formation of a cationic [Re(CO)(3)(L-3)](+) complex with tripodal coordination of the organic ligand could be achieved by the addition of Ag(PF6) to the reaction mixture. The obtained rhenium(I) complexes were studied spectroscopically and by X-ray diffraction.

The salicylidene Schiff bases of bis(2‐aminophenyl)diselenide and ‐ditelluride react with [MIICl2(PPh3)2] (M = Ni, Pt) or [PdII(OAc)2(PPh3)2] with formation of square‐planar complexes with the general formulae [MII(LY)(PPh3)] (M = Ni, Pd, Pt, Y = Se, Te). The ligands coordinate to the metals as tridentate {O,N,Se/Te} chelates. The reduction of the dichalcogenides and the formation of the chalcogenolato ligands occurs in situ by released PPh3 ligands. A mechanism for such reactions has been derived from the experimental data with the aid of DFT calculations. It suggests a higher polarization of the dichalcogenide bond with partial charge separation upon coordination to a metal centre, which therefore facilitates the cleavage of the dichalcogenide bond with PPh3. In accordance with the proposed mechanism, best yields are obtained with a strict exclusion of oxygen, but in the presence of water.

One‐pot reactions of the catechol‐scaffolding aroylbis(N,N‐diethylthiourea) H2Lcat with mixtures of alkaline earth nitrates M(NO3)2 (M2+ = Ca2+, Sr2+ or Ba2+) and (NEt4)[AuCl4] or [Au(tht)Cl] (tht = tetrahydrothiophene) in methanol in the presence of Et3N as supporting base give rise to neutral trinuclear gold(I) {2}‐metallacoronates with the composition of {M ⊂ [Au2(Lcat)2]} (1). Similar reactions with the pyridine‐centered aroylbis(N,N‐diethylthiourea) H2Lpy, however, produce complexes with the same metal‐to‐ligand ratio but with higher nuclearity {2M ⊂ [Au4(Lpy)4]} (2). In both 1 and 2, Au(I) ions are exclusively S‐bonded with the organic ligands and adopt a virtually linear coordination fashion. Such metal‐ligand binding is responsible for the formation of metallacoronands, which accommodate alkaline earth metal ions in their molecular voids, thereby resulting in host–guest coordination assemblies. The level of metal‐ligand aggregation in the resulting assemblies is dependent on the denticity, size and flexibility of the centered building block of the aroylbis(N,N‐diethylthiourea) ligands.

Chemical properties and biological activity of Au(III) compounds obtained from dichlorido[2‐(dimethylaminomethyl)phenyl‐C1,N]gold(III), [Au(damp‐C1,N)Cl2], and halogenated, potentially tridentate thiosemicarbazones have been studied. The results of this work show that the complexation of the halogenated thiosemicarbazones with Au(III) enhances their stability against hydrolysis and retains or enhances their anti‐parasitic activity. Fluorination in the periphery of the ligands has expectedly no influence on the structural chemistry of the obtained Au(III) complexes, but modulates their biological behaviour. Best results with a remarkably high selectivity index for the trypomastigote form of Trypanosoma cruzi were obtained with the complex containing the ligand, which presents a 3,5‐fluorine substitution in meta‐position of an aromatic ring, [Au(dampH)(L‐3,5‐F)]Cl.

We report a study on the structure directing effects of functional groups and counterions. The aim was to find a facile and high yielding synthetic procedure to obtain polyoxometalate (POM) building blocks for post- functionalisation. Therefore, solvothermal reactions of VOSO4 with various tris(hydroxymethyl)methane derivatives in alkaline methanolic solutions were investigated. In doing so, new POM fragments were isolated and characterised. The binding modes of the functionalised tripodal alkoxides turned out to be surprisingly different.