European Journal of Inorganic Chemistry

To harness radiometals in clinical settings, a chelator forming a stable complex with the metal of interest and targets the desired pathological site is needed. Toward this goal, we previously reported a unique set of chelators that can stably bind to both large and small metal ions, via a conformational switch. Within this chelator class, py-macrodipa is particularly promising based on its ability to stably bind several medicinally valuable radiometals including large 132/135 La3+ , 213 Bi3+ , and small 44 Sc3+ ...

A series of isomeric bis(alkylthiocarbamate) copper complexes have been synthesized, characterized, and evaluated for antiproliferation activity. The complexes were derived from ligand isomers with 3-methylpentyl (H2 L2 ) and cyclohexyl (H2 L3 ) backbone substituents, which each yield a pair of linkage isomers. The thermodynamic products CuL2a/3a have two imino N and two S donors resulting in three five-member chelate rings (555 isomers). The kinetic isomers CuL2b/3b have one imino and one hydrazino N donor and two S donors resulting in four-, six-, and five-member rings (465 isomers)...

A combination of NMR studies and quantum chemical calculations were employed to investigate the structure and energetics of Zr4+ chelates of pNO2 Bn-DOTA. We have demonstrated that two discrete regioisomeric chelates are generated during the complex formation. The nitrobenzyl substituent can adopt either an equatorial corner or side position on the macrocyclic ring. These regioisomers are incapable of interconversion and were isolated by HPLC. The corner isomer is more stable than the side, and the SAP conformer of both regioisomers is energetically more favorable than the corresponding TSAP conformer...

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 MnI FeII MnI , MnI CoII MnI , MnI MnII MnII MnI and MnI CoII CoII MnI metal assemblies with corresponding complicated magnetic and electrochemical properties...

Amidoximated absorbents (AO-PAN) effectively remove U(VI) from aqueous solution, but previous studies reported more variability for complex natural waters that contain additional confounding ions and molecules. Ternary phases containing U(VI), M(III) (M = Fe(III), Al(III), Ga(III)), and organic molecules exist under these conditions and cause heterogeneous U(VI) uptake on AO-PAN. The goal of the current study is to provide additional insights into the structural features ternary complexes using N-(2-hydroxyethyl)-iminodiacetic acid (HEIDI) as the model organic chelator and explore the relevance of these species on U(VI) capture...

The mitochondrial calcium uniporter (MCU) mediates uptake of calcium ions (Ca2+ ) into the mitochondria, a process that is vital for maintaining normal cellular function. Inhibitors of the MCU, the most promising of which are dinuclear ruthenium coordination compounds, have found use as both therapeutic agents and tools for studying the importance of this ion channel. In this study, six Co3+ cage compounds with sarcophagine-like ligands were assessed for their abilities to inhibit MCU-mediated mitochondrial Ca2+ uptake...

The formal Cu(III) complex [Cu(CF3 )4 ]1- has often served as a paradigmatic example of challenging oxidation state assignment - with many reports proposing conflicting descriptions. Here we report a computational analysis of this compound, employing Energy Decomposition Analysis and Intrinsic Bond Orbital Analysis. We present a quasi-d 10 perspective of the metal centre, resulting from ambiguities in d- electron counting. The implications for describing reactions which undergo oxidation state changes, such as the formal reductive elimination from the analogous [Cu(CF3 )3 (CH2 Ph)]1- complex (Paeth et al...

The solid-state thermal structure transformation of methylammonium vanadate, (CH3 NH3 )VO3 , from -150 °C to 350 °C is reported. Variable-temperature X-ray single-crystal structure analysis at 23, 0, -50, -100, and -150 °C reveal (CH3 NH3 )VO3 comprises of methylammonium cations and "snake-like" ([VO3 ]- )n anion chains propagating along the c -direction in the Pna 21 space group. In between -150 and -100 °C, we observe a reversible structural transformation due to the re-orientation of the methylammonium cations in the crystal packing, which is also confirmed by the reversible profiles observed in differential scanning calorimetry...

The oxygen-evolving complex (OEC) located in photosystem II (PSII) of green plants is one of the best-known examples of a manganese-containing enzyme in nature, but it is also used in a range of other biological processes. OEC models incorporate two multi-dentate nitrogen-containing ligands coordinated to a bis-μ-oxo Mn(III,IV) core. Open-chain ligands were the initial scaffold used for biomimetic studies, but their macrocyclic counterparts have proven to be particularly appropriate due to their enhanced stability...

The generation of diphosphorus molecules P2 under mild conditions in solution is a useful strategy to generate diphosphines via [4+2] cycloadditions. We recently described the release of P2 units from the nickel butterfly complex [{(IMes)Ni(CO)}2 (μ2 ,η2 :η2 -P2 )] (IMes=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene) upon addition of CO gas. Herein, we developed an alternative protocol for the same process using heterocumulenes. In addition to formation of P4 (the dimerisation product of P2 ), the reactions afford nickel complexes of novel pincer-type ligands...

The diorgano(bismuth)alcoholate [Bi((C6 H4 CH2 )2 S)OPh] ( 1-OPh ) has been synthesized and fully characterized. Stoichiometric reactions, UV/Vis spectroscopy, and (TD-)DFT calculations suggest its susceptibility to homolytic and heterolytic Bi-O bond cleavage under given reaction conditions. Using the dehydrocoupling of silanes with either TEMPO or phenol as model reactions, the catalytic competency of 1-OPh has been investigated (TEMPO=(tetramethyl-piperidin-1-yl)-oxyl). Different reaction pathways can deliberately be addressed by applying photochemical or thermal reaction conditions and by choosing radical or closed-shell substrates (TEMPO vs...

Valence tautomerism has had a remarkable impact on several branches of transition metal chemistry. By switching between different valence tautomeric states, physicochemical properties and reactivities can be triggered reversibly. Is this phenomenon transferrable into the p-block - or is it already happening there? This Perspective collects observations of p-block element-ligand systems that might be assignable to valence tautomerism. Further, it discusses occurrences in p-block element compounds that exhibit the related effect of redox-induced electron transfer...

Due to their transition metal-like behavior divalent group 14 compounds bear huge potential for their application in bond activation reactions and catalysis. Here we report on detailed computational studies on the use of ylide-substituted tetrylenes in the activation of dihydrogen and phenol. A series of acyclic and cyclic ylidyltetrylenes featuring various α-substituents with different σ - and π -donating capabilities have been investigated which demonstrate that particularly π -accepting boryl groups lead to beneficial properties and low barriers for single-site activation reactions, above all in the case of silylenes...

A series of Cu(I) complexes of bidentate or tetradentate Schiff base ligands bearing either 1- H -imidazole or pyridine moieties were synthesized. The complexes were studied by a combination of NMR and X-ray spectroscopic techniques. The differences between the imidazole- and pyridine-based ligands were examined by 1 H, 13 C and 15 N NMR spectroscopy. The magnitude of the 15 Nimine coordination shifts was found to be strongly affected by the nature of the heterocycle in the complexes. These trends showed good correlation with the obtained Cu-Nimine bond lengths from single-crystal X-ray diffraction measurements...

A series of cobalt complexes, stabilized by a monoanionic tridentate NCN pincer ligand, was synthetized and characterized. Preparation of the paramagnetic 15 VE complex [Co(NCNCH2 -Et)Br] ( 1 ) was accomplished by transmetalation of Li[2,6-(Et2 NCH2 )2 C6 H3 ] with CoBr2 in THF. Treatment of this air-sensitive compound with NO gas resulted in the formation of the diamagnetic Co(III) species [Co(NCNCH2 -Et)(NO)Br] ( 2 ) as confirmed by X-ray diffraction. This complex features a strongly bent NO ligand (Co-N-O∠135...

The multiredox reactivity of bioinorganic cofactors is often coupled to proton transfers. Here we investigate the structural, thermochemical, and electronic structure of ruthenium-amino/amido complexes with multi- proton-coupled electron transfer reactivity. The bis(amino)ruthenium(II) and bis(amido)ruthenium(IV) complexes [RuII (bpy)(en*)2 ]2+ ( RuII -H0 ) and [RuIV (bpy)(en*-H2 )2 ]2+ ( RuIV -H2 ) interconvert reversibly with the transfer of 2e- /2H+ (bpy = 2,2'-bipyridine, en* = 2,3-diamino-2,3-dimethylbutane)...

ZF proteins are ubiquitous eukaryotic proteins that play important roles in gene regulation. ZFs contain small domains made up of a combination of four cysteine and histidine residues, and are classified based up on the identity of these residues and their spacing. One emerging class of ZFs are the Cys3 His (or CCCH) class of ZFs. These ZFs play key roles in regulating RNA. In this minireview, an overview of the CCCH class of ZFs, with a focus on tristetraprolin (TTP) is provided. TTP regulates inflammation by controlling cytokine mRNAs, and there is an interest in modulating TTP activity to control inflammation...

The β-diketone scaffold is a commonly used synthetic intermediate, and is a functional group found in natural products such as curcuminoids. This core structure can also act as a chelating ligand for a variety of metals. In order to assess the potential of this scaffold for medicinal inorganic chemistry, seven different κ2 -O,O'-chelating ligands were used to construct Ru(II) complexes with polypyridyl co-ligands, and their biological activity was evaluated. The complexes demonstrated promising structure-dependent cytotoxicity...

Cooperative reactivity between transition metals and ligands, or between two metals, has created significant opportunities for the development of new transformations that would be difficult to carry out with a single metal. Here we explore cooperativity between transition metals and divalent heavier group 14 elements (tetrylenes), a less-explored facet of the field of cooperativity. Tetrylenes combine their strong σ -donor properties with an empty p -orbital that can accept electron density. This ambiphilicity has allowed them to form metal tetrylene and metallotetrylene complexes that place a reactive site adjacent to the metal...

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 (1 H/13 C/103 Rh-NMR, IR, HR-MS), structural (single crystal XRD) and electrochemical (CV) methods and their properties were compared to those of isoelectronic cobaltocenium compounds...