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Reactions of 2,6‐dipicolinoylbis(N,N‐diethylthiourea) (H2LEt) with common tellurium(IV) starting materials such as PhTeBr3 or TeBr4 yield various tellurium(IV) and tellurium(II) compounds depending on the conditions applied. Equimolar amounts of H2LEt and PhTeBr3 give the 1 : 1 complex [PhTeIVBr3(H2LEt)], while with an excess of H2LEt, the tellurium compound is partially reduced and a {PhTeII}+ building block coordinates to both sulfur atoms of H2LEt under the formation of the ion pair [PhTeII(H2LEt)][PhTeIVBr4]. Similar reactions between H2LEt and TeBr4 give the neutral monomer [TeIIBr2(H2LEt)] or the coordination polymer [TeIIBr2(H2LEt)]∞. The latter compound is also formed with the assistance of Pb2+ ions. While the lead ions do not appear in the isolated product, similar reactions with transition metal ions such as Ni2+, Mn2+, or Co2+ result in the formation of heterobimetallic complexes, in which Te(II) building blocks are directed to the sulfur atoms of the deprotonated ligand {H2LEt2‐S,S}2−, while the transition metal ions occupy central coordination positions between two of the organic ligands using the pyridine nitrogen atom, carbonyl oxygen atom(s) and/or the nitrogen atoms of the thiourea units. [ABSTRACT FROM AUTHOR]

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Copyright of Nachrichten aus der Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The homogeneously catalyzed Guerbet upgrading of ethanol to butanol can be modulated by the application of partial H2 pressure before the reaction. Ruthenium(II) PNP pincer complexes with methylene‐extended acridine‐based ligands and singly‐chelated ruthenium(II) complexes with PN ligands perform best at very low catalyst loadings and upon the application of catalyst‐specific pre‐reaction partial H2 pressure. The combination of ruthenium(II) PNP pincer complexes and manganese(I) pincer complexes with MACHO‐type PNP ligands allows for even lower ruthenium loadings while retaining low base load and consumption, thus enabling high space‐time yields, catalyst productivity and recyclability. Mechanistically, Mn is proposed to stabilize coordinatively unsaturated Ru species and allow coordination of ethoxide to Ru instead of attacking the electrophilic ligand backbone based on NMR spectroscopy and X‐ray crystallography. [ABSTRACT FROM AUTHOR]

Reactions of the technetium(I) nitrosyl complex [Tc(NO)(Cp)(PPh3)Cl] with triphenylphosphine chalcogenides EPPh3 (E = O, S, Se), and Ag(PF6) in a CH2Cl2/MeOH mixture (v/v, 2/1) result in an exchange of the chlorido ligand and the formation of [Tc(NO)(Cp)(PPh3)(EPPh3)](PF6) compounds. The cationic acetonitrile complex [Tc(NO)(Cp)(PPh3)(NCCH3)]+ is formed when the reaction is conducted in NCCH3 without additional ligands. During the isolation of the corresponding PF6− salt a gradual decomposition of the anion was detected in the solvent mixture applied. The yields and the purity of the product increase when the BF4− salt is used instead. The acetonitrile ligand is bound remarkably strongly to technetium and exchange reactions readily proceed only with strong donors, such as pyridine or ligands with 'soft' donor atoms, such as the thioether thioxane. Substitutions on the cyclopentadienyl ring do not significantly influence the ligand exchange behavior of the starting material. 99Tc NMR spectroscopy is a valuable tool for the evaluation of reactions of the complexes of the present study. The extremely large chemical shift range of this method allows the ready detection of corresponding ligand exchange reactions. The observed 99Tc chemical shifts depend on the donor properties of the ligands. DFT calculations support the discussions about the experimental results and provide explanations for some of the unusual findings. [ABSTRACT FROM AUTHOR]

A first example of an aryltellurium(II) compound with three different bonding modes to iodine featuring covalent and non‐covalent bonds such as two orthogonal, ambiphilic σ‐hole interactions is introduced: [MesTe(I)(I2)(I3)]−. It is a member of a series of mesityltellurenyl anions, which are formed during reactions of (MesTe)2 with ZnI2, phenanthroline (phen) and iodine. [Zn(phen)3][MesTe(I)2] (1), [Zn(phen)3][{MesTe(I)‐(I)...Te(I)Mes}{MesTeI2}] (2) and [Zn(phen)3][MesTe(I)(I2)(I3)][MesTeI2] (3) are isolated depending on the amount of iodine used. The products contain tellurium atoms bonded to a variety of iodine species (I−, μ2‐I−, I2 and I3−) and are, thus, perfectly suitable to explore the amphiphilic behavior of tellurium(II) and its relevance for the formation of non‐covalent bonds, where tellurium acts as both donor and acceptor simultaneously. The character of chalcogen and halogen bonds are evaluated by the combination of crystallographic data and computational methods. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The chemistry of the rhenium trihydrido complex [ReH3(PPh3)4] (1) has been reinvestigated. An improved synthesis and the solid‐state structure of the compound as well as several reactions are reported. The solid‐state structure of 1 is similar to that of [TcH3(PPh3)4] having a capped‐octahedral coordination sphere. The PPh3 ligands surround the Re atom in a trigonal‐pyramidal mode with a short apical Re−P bond (2.300(2) Å) and three longer basal bonds (2.429(2)–2.449(2) Å). Reactions of 1 with monodentate phosphines such as PMe3 or PBu3 give the mono‐substituted complexes [ReH3(PPh3)3(PMe3)] (2) and [ReH3(PPh3)3(PBu3)] (3) under retention of the apical PPh3 ligand and substitution of one of the basal PPh3 ligands. The stability of the phosphine trihydride complexes decreases in the order PPh3>PMe3>PBu3. Treatment of [ReH3(PPh3)4] with trityl hexafluorophosphate in CH3CN does not result in a hydride abstraction, but gives the tetrahydrido cation [ReH4(NCCH3)(PPh3)3]+ (4), while reactions with nitriles give unstable azavinylidene complexes of the composition [ReH2(PPh3)3(NC(H)R)] (5). They are formed by an insertion of the nitrile into a Re−H bond. The solid‐state structure of the methyl derivative [ReH2(PPh3)3(NC(H)CH3)] (5 a) was determined showing a linear Re−N−C unit with rhenium−nitrogen and nitrogen−carbon double bonds, while the N=CH−C bond is clearly bent with an angle of 124°. Two previously unknown polymorphs of [ReH5(PPh3)3] were isolated from reactions of 1 with HOC6H3(CH3)2 and thiourea after prolonged heating in toluene and characterized by IR spectroscopy and X‐ray diffraction. [ABSTRACT FROM AUTHOR]

The reaction of [TcI(NO)(LOMe)(PPh3)Cl] ({LOMe}−=η5‐cyclopentadienyltris(dimethyl phosphito‐P)cobaltate(III)) with Ag(PF6) gives two unexpected products: the dimeric technetium(I) complex [{Tc(NO)(LOMe)(PPh3)Cl}2Ag](PF6) with a central Ag+ ion and the cationic Tc(II) compound [Tc(NO)(LOMe)(PPh3)Cl](PF6). The products have been studied spectroscopically and by X‐ray diffraction. [ABSTRACT FROM AUTHOR]

Ammonium pertechnetate reacts in mixtures of trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid under final formation of ammonium pentakis(trifluoromethanesulfonato)oxidotechnetate(V), (NH4)2[TcO(OTf)5]. The reaction proceeds only at exact concentrations and under the exclusion of air and moisture via pertechnetyl trifluoromethanesulfonate, [TcO3(OTf)], and intermediate TcVI species. 99Tc nuclear magnetic resonance (NMR) has been used to study the TcVII compound and electron paramagnetic resonance (EPR), 99Tc NMR and X‐ray absorption near‐edge structure (XANES) experiments indicate the presence of the reduced technetium species. In moist air, (NH4)2[TcO(OTf)5] slowly hydrolyses under formation of the tetrameric oxidotechnetate(V) (NH4)4[{TcO(TcO4)4}4] ⋅10 H2O. Single‐crystal X‐ray crystallography was used to determine the solid‐state structures. Additionally, UV/Vis absorption and IR spectra as well as quantum chemical calculations confirm the identity of the species. [ABSTRACT FROM AUTHOR]

The salicylidene Schiff bases of bis(2‐aminophenyl)diselenide and ‐ditelluride react with [ReOCl3(PPh3)2] or the arylimidorhenium(V) compounds [Re(NPhR)Cl3(PPh3)2] (R = H, F, CF3) with formation of rhenium(V) complexes with tridentate {O,N,Se/Te} chalcogenolato ligands. The ligands adopt a facial coordination mode with the oxygen donors trans to the multiply bonded O2– or NPhR2– ligands. The reduction of the dichalcogenides and the formation of the chalcogenolato ligands occurs in situ by released PPh3 ligands. The absence of additional reducing agents provides good yields of products with rhenium in the high formal oxidation state "+5". A mechanism for the dichalcogenide reduction is proposed on the basis of the experimental results. In accordance with the proposed mechanism, best yields are obtained with a strict exclusion of oxygen, but in the presence of water. [ABSTRACT FROM AUTHOR]