Precursor molecules for 1,2-diamidobenzene containing cobalt(II), nickel(II) and zinc(II) complexes - synthesis and magnetic properties.

Molecular magnetic materials based on 1,2-diamidobenzenes are well known and have been intensively studied both experimentally and computationally. They possess interesting magnetic properties as well as redox activity. In this work, we present the synthesis and investigation of potent synthons for constructing discrete metal-organic architectures featuring 1,2-diamidobenzene-coordinated metal centres.

Air-Stable Dinuclear Complexes of Four-Coordinate Zn and Ni Ions with a Radical Bridge: A Detailed Look at Redox Activity and Antiferromagnetic Coupling.

Air-stable dinuclear complexes [(bmsab)Ni(tmsab)Ni(bmsab)] and [(bmsab)Zn(tmsab)Zn(bmsab)] (bmsab = bis(methanesulfoneamido)benzene, tmsab = tetra(methanesulfonamido)benzene) were prepared via a synthetic route based on heteroleptic precursor complexes. The new complexes combine a distorted tetrahedral coordination environment with an open-shell bridging ligand. The Zn species was subjected to a detailed investigation of the (spectro-)electrochemical processes.

Well-Defined Iron Sites in Crystalline Carbon Nitride.

Carbon nitride materials can be hosts for transition metal sites, but Mössbauer studies on iron complexes in carbon nitrides have always shown a mixture of environments and oxidation states. Here we describe the synthesis and characterization of a crystalline carbon nitride with stoichiometric iron sites that all have the same environment. The material (formula CNHFeLiCl, abbreviated PTI/FeCl) is derived from reacting poly(triazine imide)·LiCl (PTI/LiCl) with a low-melting FeCl/KCl flux, followed by anaerobic rinsing with methanol.

Spin State in Homoleptic Iron(II) Terpyridine Complexes Influences Mixed Valency and Electrocatalytic CO Reduction.

Two homoleptic Fe(II) complexes in different spin states bearing superbasic terpyridine derivatives as ligands are investigated to determine the relationship between spin state and electrochemical/spectroscopic behavior. Antiferromagnetic coupling between a ligand-centered radical and the high-spin metal center leads to an anodic shift of the first reduction potential and results in a species that shows mixed valency with a moderately intense intervalence-charge-transfer band. The differences afforded by the different spin states extend to the electrochemical reactivity of the complexes: while the low-spin species is a precatalyst for electrocatalytic CO reduction and leads to the preferential formation of CO with a Faradaic efficiency of 37%, the high-spin species only catalyzes proton reduction at a modest Faradaic efficiency of approximately 20%.

Rhodium diamidobenzene complexes: a tale of different substituents on the diamidobenzene ligand.

Diamidobenzene ligands are a prominent class of redox-active ligands owing to their electron reservoir behaviour, as well as the possibility of tuning the steric and the electronic properties of such ligands through the substituents on the N-atoms of the ligands. In this contribution, we present Rh(iii) complexes with four differently substituted diamidobenzene ligands. By using a combination of crystallography, NMR spectroscopy, electrochemistry, UV-vis-NIR/EPR spectroelectrochemistry, and quantum chemical calculations we show that the substituents on the ligands have a profound influence on the bonding, donor, electrochemical and spectroscopic properties of the Rh complexes.

Spin-state control of cobalt(II) and iron(II) complexes with click-derived tripodal ligands through non-covalent and fluorine-specific interactions.

The fine-tuning of intermolecular or intramolecular non-covalent interactions (NCIs) and thus the precise synthesis of metal complexes in which the spin states can be controlled by NCIs remains challenging, even though several such complexes have been intensively studied. In this regard, we present mononuclear cobalt(II) and iron(II) complexes with "click"-derived tripodal ligands that contain fluorinated benzyl substituents in the secondary coordination sphere. The complexes were co-crystallized with different solvent molecules to decipher the effect of the crystallized solvents on NCIs, and on the spin state of the metal ion.

The transformations of a methylene-bridged bis-triazolium salt: a mesoionic carbene based metallocage and analogues of TCNE and NacNac.

Unusual and unexpected chemical transformations often provide access to completely new types of functional molecules. We report here the synthesis of a methylene-bridged bis-triazolium salt designed as a precursor for a new bis-mesoionic carbene (MIC) ligand. The direct metalation with silver oxide led to the isolation and crystallographic characterization of a cationic tetranuclear octacarbene-silver(i) complex.

Correction: Tethered CAAC-CAAC dimers: oxidation to persistent radical cations and bridging-unit dependent reactivity/stability of the dications.

Correction for 'Tethered CAAC-CAAC dimers: oxidation to persistent radical cations and bridging-unit dependent reactivity/stability of the dications' by Mithilesh Kumar Nayak et al., Chem. Commun.

Tethered CAAC-CAAC dimers: oxidation to persistent radical cations and bridging-unit dependent reactivity/stability of the dications.

Herein, we report tethered cyclic(alkyl)(amino)carbene (CAAC) dimers in which two CAAC-motifs are connected by an ethylene-, trans-1,2-cyclohexylene- and propylene-spacer through their N-centres. The 1-electron oxidized radical cations are isolable, whereas a significant influence of the bridging unit on the chemical reactivity becomes apparent in and with the 2-electron oxidized products.

A coordinatively unsaturated iridium complex with an unsymmetrical redox-active ligand: (spectro)electrochemical and reactivity studies.

Redox-active ligands, owing to their electron reservoir capability, are well suited for the generation of coordinatively unsaturated metal complexes. We present here iridium complexes with an unsymmetrically substituted o-phenylenediamine ligand. A coordinatively unsaturated, formally iridium(iii) complex with the fully reduced o-phenylenediamide (or o-diamidobenzene) ligand was isolated and structurally characterized.

Influence of -Substitution on the Formation and Oxidation of NHC-CAAC-Derived Triazaalkenes.

We have studied the effect of -substitution on the course of the reaction of imidazolium triflate. The reaction of -heterocyclic carbene with -Bu-substituted pyrrolinium triflate afforded 2-(pyrrolidin-2-yl)-imidazolium triflate, . Treatment of with potassium bis(trimethylsilyl)amide (KHMDS) leads to either the dealkylation product or the deprotonation product, triazaalkene , depending on the -substitution at the imidazolium moiety.

Efficient Syntheses of New Super Lewis Basic Tris(dialkylamino)-Substituted Terpyridines and Comparison of Their Methyl Cation Affinities.

Syntheses of very electron-rich dialkylamino-substituted 2,2':6',2''-terpyridines (TPYs) were adapted to moderate scale preparation without tedious purification of intermediates. The key 4'-bromo-6,6''-dimethyl-2,2':6',2''-terpyridine-4,4''-diyl bisnonaflate is now available in gram quantities. Its nucleophilic aromatic substitution with dimethylamine provided mixtures of 4'-bromo-substituted 4,4''-bis(dimethylamino)-TPY and the tris(dimethylamino)-TPY.

A heterobimetallic superoxide complex formed through O2 activation between chromium(II) and a lithium cation.

The reaction of 1,1,3,3-tetraphenyl-1,3-disiloxandiol (LH2) with n-butyllithium and CrCl2 results in a mononuclear chromium(II) complex (1) that further reacts with O2 at low temperatures to yield a mononuclear chromium(III) superoxide complex [L2CrO2(THF)][Li2(THF)3] (2). The crystal structure revealed that the chromium superoxido entity is stabilized by the coordination to an adjacent lithium cation. Complex 2 thus contains an unprecedented heterobimetallic [Cr(III)(μ-O2)Li(+)] core; beyond this it is the first chromium superoxide for which a temperature-dependent magnetic characterization could be achieved, and the first structurally characterized representative with chromium in an exclusive O-donor environment.