Clathrochelate Complexes Containing Axial Cymantrene and Tromancenium Moieties.

New clathrochelate complexes of manganese, iron and cobalt containing peripheral organometallic manganese moieties cymantrene or tromancenium were synthesized via self-assembly from di/tri-topic dioximes, metal templates and cymantrene/tromancenium boronic acid pinacol esters. These air-stable, highly colored, oligometallic complexes are composed of various combinations of MnFeMn, MnCoMn, MnMnMnMn and MnCoCoMn metal assemblies with corresponding complicated magnetic and electrochemical properties. Full spectroscopic and structural characterization by H/B/C NMR, HRMS, IR, UV-vis, single crystal XRD and CV (cyclic voltammetry) is provided.

Curious Case of Cobaltocenium Carbaldehyde.

Cobaltocenium carbaldehyde (formylcobaltocenium) hexafluoridophosphate, a long sought-after functionalized cobaltocenium salt, is accessible from cobaltocenium carboxylic acid by a three-step synthetic sequence involving (i) chlorination to the acid chloride, (ii) copper-borohydride reduction to the hydroxymethyl derivative, and (iii) Dess-Martin oxidation to the title compound. Due to the strongly electron-withdrawing cationic cobaltocenium moiety, no standard aldehyde reactivity is observed. Instead, nucleophilic addition followed by haloform-type cleavage prevails, thereby ruling out common useful aldehyde derivatization.

(η-Carb-oxy-cyclo-penta-dien-yl)(η-cyclo-hepta-trien-yl)manganese(I) hexa-fluorido-phosphate.

The title compound, [Mn(CH)(CHO)]PF or [(Cht)Mn(Cp'COH)]PF, with Cht = cyclo-hepta-trienyl and Cp' = CH, is an air-stable, purple, heteroleptic, cationic sandwich complex with manganese in oxidation state +I and π-coordinating cyclo-hepta-trienyl and cyclo-penta-dienyl ligands. The latter ligand carries the carb-oxy-lic acid functionality. This 'tromancenium-8-carb-oxy-lic acid' with hexa-fluorido-phosphate as counter-ion represents a rare case of a cationic carb-oxy-lic acid.

Bis(μ-cobaltoceniumseleno-late-1:2κ :)bis[bis-(cobaltoceniumseleno-late-κ)mercury(II)] tetra-kis-(hexa-fluorido-phosphate) aceto-nitrile disolvate.

The title compound, [CoHg(CH)(CHSe)](PF)·2CHCN or [Hg(CcSe)][PF]·2CHCN (Cc = CHCo), was obtained as bright-orange needle-shaped crystals. It is a salt containing a tetra-cationic dimercury species with six cobaltoceniumseleno-late ligands, four hexa-fluorido-phosphate counter-ions and two aceto-nitrile solvent mol-ecules. The cation (point group ) has a bi-tetra-hedral {HgSe} core with two bridging Se atoms and four terminal Se atoms.

Borylated Cymantrenes and Tromancenium Salts with Unusual Reactivity.

In continuation of our study of the chemistry of cationic (cycloheptatrienyl)(cyclopentadienyl)manganese(I) sandwich complexes, so-called "tromancenium" salts, we report here on their boron-substituted derivatives focusing on useful boron-mediated synthetic applications. Transmetalation of lithiated tricarbonyl(cyclopentadienyl)manganese ("cymantrene") with boric or diboronic esters affords monoborylated cymantrenes that are converted by advanced high-power LED photosynthesis followed by oxidation with tritylium to their 8-boron-substituted tromancenium complexes. These new functionalized tromancenium salts are fully characterized by H/B/C/F/Mn NMR, IR, UV-vis, HRMS spectroscopy, single-crystal structure analysis (XRD) and cyclic voltammetry (CV).

Rhodocenium Functionalization Enabled by Half-Sandwich Capping, Zincke Reaction, Diazoniation and Sandmeyer Chemistry.

In continuation of our exploration of metallocenium chemistry we report here on innovative ways toward monofunctionalized rhodocenium salts applying half-sandwich capping reactions of cyclopentadienyl rhodium(III) halide synthons with cyclopentadienyl ylides containing pyridine, phosphine or dinitrogen leaving groups, followed by Zincke and Sandmeyer reactions. Thereby amino, diazonio, bromo, azido and iodo rhodocenium salts containing valuable functional groups are accessible for the first time. Target compounds were characterized by spectroscopic (H/C/Rh-NMR, IR, HR-MS), structural (single crystal XRD) and electrochemical (CV) methods and their properties were compared to those of isoelectronic cobaltocenium compounds.

Cobaltoceniumselenolate Gold(I) Complexes: Synthesis, Spectroscopic, Structural and Anticancer Properties.

Cobaltoceniumselenolate is an unusual, highly air-sensitive, mesoionic compound containing a very soft anionic selenium donor atom. Here we explore its coordination chemistry with Au(I) metal centers and show that its hetero- and homoleptic gold complexes are highly colored, air-stable compounds, which were characterized by H/C/P/Se NMR, IR, UV-Vis, HR-MS and single crystal XRD. Cytotoxicity of these polar, water-soluble complexes was studied against various standard cancer cell lines (A549MDA-MB-231, HT-29) revealing good anticancer activity of all three complexes.

(Cobaltoceniumyl-amido)-pyridinium hexa-fluorido-phosphate.

The title compound, [Co(CH)(CHN)]PF, was synthesized from deproton-ated 1-amino-pyridinium iodide, followed by microwave-assisted nucleophilic aromatic substitution of iodo-cobaltocenium iodide. After anion exchange with potassium hexa-fluorido-phosphate, the title compound crystallizes as orange prisms in the space group . This very stable pyridine nitrene adduct is the first example of a cobaltocenium derivative, formally containing a nitrene nitro-gen species.

Oxidative access via to an electrophilic, mesoionic dicobaltoceniumyltriazolylidene gold(III) catalyst.

A gold(III) complex with the hitherto most electron poor mesoionic carbene ligand is presented. Aqua regia was the oxidizing agent of choice for the synthesis of this unusual organometallic compound. The Au complex is redox-rich, and also acts as a catalyst for oxazole formation, delivering selectively a completely different isomer compared to its Au congener.

Direct Amination of Cobaltocenium Hexafluoridophosphate via Vicarious Nucleophilic Substitution.

In this communication we report a convenient, as short as possible synthesis of aminocobaltocenium hexafluoridophosphate, a very useful compound for further functionalization in cobaltocenium chemistry. Via vicarious nucleophilic substitution of hydrogen of cobaltocenium hexafluoridophosphate with 1,1,1-trimethylhydrazinium iodide as nucleophile bearing its own leaving group, a one-step amination of cobaltocenium in 50% isolated yield is possible, a major improvement over the standard multistep procedure involving common Curtius rearrangement chemistry.

Redox-Rich Metallocene Tetrazene Complexes: Synthesis, Structure, Electrochemistry, and Catalysis.

Thermal or photochemical metal-centered cycloaddition reactions of azidocobaltocenium hexafluoridophosphate or azidoferrocene with (cyclooctadiene)(cyclopentadienyl)cobalt(I) afforded the first metallocenyl-substituted tetrazene cyclopentadienyl cobalt complexes together with azocobaltocenium or azoferrocene as side products. The trimetallic CpCo compounds are highly conjugated, colored, and redox-active metallo-aromatic compounds, as shown by their spectroscopic, structural, and electrochemical properties. The CpCo-tetrazenido complex with two terminally appended cobaltocene units catalyzes electrochemical proton reduction from acetic acid at a mild overpotential (0.

Crystal structures of 1'-amino-cobaltocenium-1-carb-oxy-lic acid chloride monohydrate and of its azo dye 1'-[2-(1-amino-2,6-dimethylphenyl)diazen-1-yl]cobaltocenium-1-carb-oxy-lic acid hexa-fluorido-phosphate monohydrate.

1'-Amino-cobaltocenium-1-carb-oxy-lic acid chloride, [Co(CHN)(CHO)]Cl·HO, (), and its azo derivative 1'-[2-(1-amino-2,6-dimethylphenyl)diazen-1-yl]cobaltocenium-1-carb-oxy-lic acid hexa-fluorido-phosphate, [Co(CHN)(CHO)]PF·HO () were obtained from cobaltocenium-1,1'-di-carb-oxy-lic acid hexa-fluorido-phosphate by converting one carboxyl group to its chloro-carboxyl derivative followed by chloride/azide exchange, Curtius rearrangement, diazo-tiation and azo coupling with 2,6-di-methyl-aniline. Both title compounds crystallize as their monohydrates. In the crystal structure of , both functional groups lie in the same direction, with the Cp rings being nearly eclipsed, and participate in an extended hydrogen-bonded supra-molecular network including the counter-ion and the water mol-ecule of crystallization.

Cobaltocenylidene: A Mesoionic Metalloceno Carbene, Stabilized in a Gold(III) Complex.

Oxidative addition of cobaltoceniumdiazonium bis(hexafluoridophosphate) with (pseudo)halide aurates gave gold(III) complexes containing zwitterionic cobaltoceniumide as a ligand. Its selenium derivative, cobaltoceniumselenolate, was obtained by an electrophilic aromatic substitution reaction of iodocobaltocenium iodide with Na Se. Spectroscopic and structural data in combination with DFT calculations showed that this cobaltocenylidene species is a mesoionic carbene quite different from common N-heterocyclic carbenes.

Highly Electrophilic, Catalytically Active and Redox-Responsive Cobaltoceniumyl and Ferrocenyl Triazolylidene Coinage Metal Complexes.

A convenient access to a triad of triazoles with ferrocenyl and cobaltoceniumyl substituents is reported. N-Alkylation, deprotonation and metalation with Cu /Ag /Au synthons affords the heteroleptic triazolylidene complexes. Due to the combination of neutral, electron-donating ferrocenyl substituents and cationic, strongly electron-withdrawing cobaltocenium substituents, the mesoionic carbene (MIC) ligands of these complexes are electronically interesting "push-pull", "pull-push" and "pull-pull" metalloligands with further switchable redox states based on their fully reversible Fe /Fe , (ferrocene/ferrocenium) and Co /Co , (cobaltocenium/cobaltocene) redox couples.

Bonding, Hyperfine Interactions, and Lattice Dynamics of Cationic and Neutral Ferrocenyl-Substituted Allylic and Cumulenic Compounds.

The synthesis and spectroscopic characterization (by mass, UV-visible, IR, NMR and (57)Fe Mössbauer spectroscopy) of three new compounds related to seven recently published ferrocenyl-substituted allylic and cumulenic compounds are reported and have made it possible to effect a systematic evaluation of the parameters extractable from temperature-dependent gamma ray resonance studies. For the neutral species, the hyperfine parameters (IS and QS) of the sigma-bonded ferrocenyl groups are insensitive to the structural details of the allylic or cumulenic carbon framework. The temperature dependence of the recoil-free fraction is dominated by the Cp ring-iron atom interaction, and is not diagnostic of the detailed molecular architecture.