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An asymmetric bis-phenol-β-diketone (H4L) has been designed as a ligand programmed to promote the assembly of a molecular arrangement composed of three magnetically exchanged [NiCu] pairs, each exhibiting an S = 1/2 spin. The latter are shown by EPR and magnetometry to be good qubit realizations and non-equivalent within the molecule in the solid state, as required for conditional quantum gates.

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Conjugated molecules with multiple radical centers such as the iconic Chichibabin diradicaloid hold promise as building blocks in materials for quantum sensing and quantum information processing. However, it is a considerable challenge to design simple analogues of the Chichibabin hydrocarbon that are chemically inert, exhibit high diradical character and emit light at a distinct wavelength that may offer an optical readout of the spin state in functional ensembles. Here we describe the serendipitous discovery of the stable TTM‐TTM diradicaloid, which exhibits high diradical character, a striking sky‐blue color and near‐infrared (NIR) emission (in solution). This combination of properties is unique among related diradicaloids and is due to the presence of hydrogen and chlorine atoms in "just the right positions", allowing a perfectly planar, yet predominantly benzenoid bridge to connect the two sterically stabilized radical centers. In‐depth studies of the optical and magnetic properties suggest that this structural motif could become a mainstay building block of organic spin materials. [ABSTRACT FROM AUTHOR]

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. The synthons feature weakly bound dimethoxyethane (dme) ligands in addition to the 1,2-diamidobenzene. We characterize these complexes and investigate their magnetic properties by means of static and dynamic magnetometry and high-field electron paramagnetic resonance (HFEPR). Interestingly, the magnetic and magnetic resonance data strongly suggest a dimeric formulation of these complexes, viz. [MII(bmsab)(dme)]2 (bmsab = 1,2-bis(methanesulfonamido)benzene; dme = dimethoxyethane) with M = Co, Ni, Zn. A large negative D-value of −60 cm−1 was found for the Co(II) synthon and an equally large negative D of −50 cm−1 for the Ni(II) synthon. For Co(II), the sign of the D-value is the same as that found for the known bis-diamidobenzene complexes of this ion. In contrast, the negative D-value for the Ni(II) complex is unexpected, which we explain in terms of a change in coordination number. The heteroleptic Co(II) complex presented here does not feature slow relaxation of the magnetization, in contrast to the homoleptic Co(II) 1,2-diamidobenzene complex. [ABSTRACT FROM AUTHOR]

We report on the synthesis and characterization of a series of (mostly) air‐stable diorganyl bis(pyridylimino) isoindolide (BPI) aluminum complexes and their chemistry upon visible‐light excitation. The redox non‐innocent BPI pincer ligand allows for efficient charge transfer homolytic processes of the title compounds. This makes them a universal platform for the generation of carbon‐centered radicals. The photo‐induced homolytic cleavage of the Al−C bonds was investigated by means of stationary and transient UV/Vis spectroscopy, spin trapping experiments, as well as EPR and NMR spectroscopy. The experimental findings were supported by quantum chemical calculations. Reactivity studies enabled the utilization of the aluminum complexes as reactants in tin‐free Giese‐type reactions and carbonyl alkylations under ambient conditions, which both indicated radical‐polar crossover behavior. A deeper understanding of the physical fundamentals and photochemical process was provided, furnishing in turn a new strategy to control the reactivity of bench‐stable aluminum organometallics. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte 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.)

Molecular entities with doublet or triplet ground states find increasing interest as potential molecular quantum bits (qubits). Complexes with higher multiplicity might even function as qudits and serve to encode further quantum bits. Vanadium(II) ions in octahedral ligand fields with quartet ground states and small zero‐field splittings qualify as qubits with optical read out thanks to potentially luminescent spin‐flip states. We identified two V2+ complexes [V(ddpd)2]2+ with the strong field ligand N,N'‐dimethyl‐N,N'‐dipyridine‐2‐yl‐pyridine‐2,6‐diamine (ddpd) in two isomeric forms (cis‐fac and mer) as suitable candidates. The energy gaps between the two lowest Kramers doublets amount to 0.2 and 0.5 cm−1 allowing pulsed EPR experiments at conventional Q‐band frequencies (35 GHz). Both isomers possess spin‐lattice relaxation times T1 of around 300 μs and a phase memory time TM of around 1 μs at 5 K. Furthermore, the mer isomer displays slow magnetic relaxation in an applied field of 400 mT. While the vanadium(III) complexes [V(ddpd)2]3+ are emissive in the near‐IR‐II region, the [V(ddpd)2]2+ complexes are non‐luminescent due to metal‐to‐ligand charge transfer admixture to the spin‐flip states. [ABSTRACT FROM AUTHOR]

A bimetallic triply fused copper(II) porphyrin complex (1) was prepared, comprising two monomeric porphyrin units linked through β–β, meso–meso, β′–β′ triple covalent linkages and exhibiting remarkable catalytic activity for the electrochemical hydrogen evolution reaction in comparison to the analogous monomeric copper(II) porphyrin complex (2). Electrochemical investigations in the presence of a proton source (trifluoroacetic acid) confirmed that the catalytic activity of the fused metalloporphyrin occurred at a significantly lower overpotential (≈320 mV) compared to the non‐fused monomer. Controlled potential electrolysis combined with kinetic analysis of catalysts 1 and 2 confirmed production of hydrogen, with 96 and 71 % faradaic efficiencies and turnover numbers of 102 and 18, respectively, with an observed rate constant of around 107 s−1 for the dicopper complex. The results thus firmly establish triply fused porphyrin ligands as outstanding candidates for generating highly stable and efficient molecular electrocatalysts in combination with earth‐abundant 3d transition metals. [ABSTRACT FROM AUTHOR]