Incorporating radical ligands into metal complexes is one of the emerging trends in the design of single-molecule magnets (SMMs). While significant effort has been expended to generate multinuclear transition metal-based SMMs with bridging radical ligands, less attention has been paid to mononuclear transition metal-radical SMMs. Herein, we describe the first α-diiminato radical-containing mononuclear transition metal SMM, namely, [κ2-PhTttBu]Fe(AdNCHCHNAd) (1), and its analogue [κ2-PhTttBu]Fe(CyNCHCHNCy) (2) (PhTttBu = phenyltris(tert-butylthiomethyl)borate, Ad = adamantyl, and Cy = cyclohexyl). 1 and 2 feature nearly identical geometric and electronic structures, as shown by X-ray crystallography and electronic absorption spectroscopy. A more detailed description of the electronic structure of 1 was obtained through EPR and Mössbauer spectroscopies, SQUID magnetometry, and DFT, TD-DFT, and CAS calculations. 1 and 2 are best described as high-spin iron(II) complexes with antiferromagnetically coupled α-diiminato radical ligands. A strong magnetic exchange coupling between the iron(II) ion and the ligand radical was confirmed in 1, with an estimated coupling constant J < -250 cm-1 (J = -657 cm-1, DFT). Calibrated CAS calculations revealed that the ground-state Fe(II)-α-diiminato radical configuration has significant ionic contributions, which are weighted specifically toward the Fe(I)-neutral α-diimine species. Experimental data and theoretical calculations also suggest that 1 possesses an easy-axis anisotropy, with an axial zero-field splitting parameter D in the range from -4 to-1 cm-1. Finally, dynamic magnetic studies show that 1 exhibits slow magnetic relaxation behavior with an energy barrier close to the theoretical maximum, 2|D|. These results demonstrate that incorporating strongly coupled α-diiminato radicals into mononuclear transition metal complexes can be an effective strategy to prepare SMMs.

Electrochemical transformations involve complex parameter interactions, ranging from universal chemistry variables such as solvent and reagents to specialist factors including electrode material and current density. Hence, the development of a robust and scale-independent electrochemical reaction can currently be a challenge. High-throughput experimentation (HTE) is an enabling method for reaction optimization and robustness testing. Here we provide an industrial and academic perspective on the state of the art of the combination of HTE with electrochemical reaction optimization for applications, including scale-up. We then present our vision for a future in which HTE reduces barriers to wide adoption of electrochemistry across the field of chemical synthesis.

Here, we report the design and application of an electrochemical flow cell that provides excellent mixing and enables high current densities on research-relevant scales (<= 1 g, up to 10 g scale). The cell design, embedding a turbulence promoter and cooling layers, as well as pressure stability, allows the use of high current densities and provides a tool for efficient high-throughput synthesis applications. The cell performance was demonstrated for reaction conditions screening and material production (436 mmol scale) with a current density of 1000 mA/cm(2) in the oxidative bis-methoxylation of furan as a reaction model.

X-ray crystallographic and theoretical charge-density data for a series of compounds—[(Co(Ts3tren))M(Co(Ts3tren))], (M = Mg, Ca, Sr and Ba)—were examined. The crystal structures were isostructural, and the alkaline-earth-metal ions had the same six-coordinate environment oxygen donor atoms which was octahedral despite the large variation in their ionic radii. The isomorphism of these molecules was surprising, and a theoretical examination of their electronic structures, with various metal ions along the series, provided detailed insight into their stabilities. The theoretical and experimental data were consistent and agreed well. The local properties of the Co(II) ion and its donor atoms were relatively independent of the alkaline earth metals.

The synthesis of 1,4-di-tert-butyl-7-R-1,4,7-triazacyclononane (tBu(2)Rtacn) derivatives through a "crab-like" cyclization is reported. The tert-butyl groups were cleavable with concentrated hydrochloric acid, allowing for a facile and convenient synthesis of the HCl salt of H(3)tacn and the most direct route to its industrially relevant binucleating N-ethylene bridged derivative, H(4)dtne. In addition, the synthesis of chiral tacn derivatives with both one and two stereocenters in non-annulet, alpha-N positions is reported.

Adducts of hydrogen peroxide and transition metals have been implicated as intermediates in biological and industrial processes but have only recently been observed. Therefore, knowledge of how hydrogen peroxide interacts with transition metals is extremely limited. Herein, we report the synthesis of H2O2 complexes of cobalt, nickel, and copper supported by sulfonamido ligands with second-sphere hydrogen bonding. Binding constant and decay kinetics are reported for four new M(H2O2) adducts, providing a foundation for future studies in H2O2 coordination and oxidation catalysis.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

O2-derived CunO2 adducts are attractive targets for aerobic oxidation catalysis because of their remarkable reactivity, but oxidation of the supporting ligand limits catalytic turnover. We report that tBu3tacn (1,4,7-tri-tert-butyl-1,4,7-triazacyclononane) supports a dicopper(II) μ-η2:η2-peroxo species with the highest solution stability outside of an enzyme. Decomposition of this species proceeds without oxidation of the tBu3tacn ligand. Additive-free catalytic aerobic oxidation reactions at or above room temperature are described, highlighting the potential of oxidatively robust ligands in aerobic copper catalysis.

M(H2 O2 ) adducts have been postulated as intermediates in biological and industrial processes; however, only one observable M(H2 O2 ) adduct has been reported, where M is redox-inactive zinc. Herein, direct solution-phase detection of an M(H2 O2 ) adduct with a redox-active metal, cobalt(II), is described. This Co(II) (H2 O2 ) compound is made observable by incorporating second-sphere hydrogen-bonding interactions between bound H2 O2 and the supporting ligand, a trianionic trisulfonamido ligand. Thermodynamics of H2 O2 binding and decay kinetics of the Co(II) (H2 O2 ) species are described, as well as the reaction of this Co(II) (H2 O2 ) species with Group 2 cations.

CoII complexes bearing sulfonamido ligands derived from tris(2-aminoethyl)amine (H6tren) assemble into complex architectures in the presence of Group II ions through interactions between the Group II ion and the sulfonyl oxygens.

In the crystal structure of the title homoleptic Cr(II) complex, [Cr(CH3CN)6](C24H20B)2·CH3CN, the [Cr(CH3CN)6](2+) cation is a high-spin d(4) complex with strong static, rather than dynamic, Jahn-Teller distortion. The electron density of the cation was determined by single-crystal X-ray refinements using aspherical structure factors from wavefunction calculations. The detailed picture of the electronic density allowed us to assess the extent and directionality of the Jahn-Teller distortion of the Cr(II) cation away from idealized octahedral symmetry. The topological analysis of the aspherical d-electron density about the Cr(II) cation showed that there are significant valence charge concentrations along the axial Cr-N axes. Likewise, there were significant valence charge depletions about the Cr(II) cation along the equatorial Cr-N bonds. These charge concentrations are in accordance with a Jahn-Teller-distorted six-coordinate complex.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Metal(H2O2) complexes have been implicated in kinetic and computational studies but have never been observed. Accordingly, H2O2 has been described as a very weak ligand. We report the first metal(H2O2) adduct, which is made possible by incorporating intramolecular hydrogen-bonding interactions with bound H2O2. This Zn(II)(H2O2) complex decays in solution by a second-order process that is slow enough to enable characterization of this species by X-ray crystallography. This report speaks to the intermediacy of metal(H2O2) adducts in chemistry and biology and opens the door to exploration of these species in oxidation catalysis.