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Understanding how magnetic nuclei affect spin relaxation is vital for designing robust spin coherence in magnetic materials and molecules. A key question is the extent that magnetic nuclei close to a spin (e.g., in the ligand shell of a metal complex) influence relaxation and how it varies over different classes of nuclei. Herein, we apply high-field EPR, X-band EPR, and ac magnetic susceptibility techniques to a family of five V(IV) complexes of the type [V(C6X4O2)3]2–, featuring five different sets of 12 nuclear spins on the ligand shell: X = 1H (1), 2H (2), 19F (3), 35/37Cl (4), and 79/81Br (5). We found several unanticipated results in these studies. For example, at high-field/-frequency, we found that compound 1, with the highest-magnetic-moment ligand nuclear spins, exhibits the longest phase memory relaxation times of the series. Furthermore, at lower fields, we found that the spin–lattice relaxation time and its field dependence were ligand-dependent, despite no obvious change in electronic structure across the five species. Based on this data, structural comparisons, and Raman spectroscopic data, we tentatively conclude that the spin–lattice relaxation properties of 1–5 stem from fine-tuning of the local magnetic environment with changing identity of the X atoms. 

Quantum objects, such as atoms, spins, and subatomic particles, haveunique physical properties that could be useful for many different applications, ranging from quantum information processing to magnetic resonance imaging. Molecular species also exhibit these quantum properties, and, importantly, these properties are fundamentally tunable by synthetic design, unlike ions isolated in a quadrupolar trap, for example. In this comment, we distill multiple, distinct, scientific efforts into an emergent field that is devoted to designing molecules that mimic the quantum properties of objects like trapped atoms or defects in solids. Mimicry is endemic in inorganic chemistry and featured heavily in the research interests of groups across the world. We describe this new field of using molecular inorganic chemistry to mimic the quantum properties (e.g. the lifetime of spin superpositions, or the resonant frequencies thereof) of other quantum objects as “quantum mimicry.” In this comment, we describe the philosophical design strategies and recent exciting results from the application of these strategies. 

Asymmetric ligands alter the low-energy vibrational spectra of a metal complex and affect the temperature dependence of⁵⁹Co NMR properties. 

Three homoleptic Fe(II) complexes with bidentate thiazole-based ligands exhibit spin-crossover (SCO) at the metal center. Abrupt temperature-driven and light-induced spin transitions are observed due to cooperative interactions between SCO cations. 

We describe reductive dehydrogenative cyclizations that form hepta-, nona-, and decacyclic anionic graphene subunits from mono- and bis-helicenes with an embedded five-membered ring. The reaction of bis-helicenes can either proceed to the full double annulation or be interrupted by addition of molecular oxygen at an intermediate stage. The regioselectivity of the interrupted cyclization cascade for bis-helicenes confirms that relief of antiaromaticity is a dominant force for these facile ring closures. Computational analysis reveals the unique role of the preexisting negatively charged cyclopentadienyl moiety in directing the second negative charge at a specific remote location and, thus, creating a localized antiaromatic region. This region is the hotspot that promotes the initial cyclization. Computational studies, including MO analysis, molecular electrostatic potential maps, and NICS(1.7)ZZ calculations, evaluate the interplay of the various effects including charge delocalization, helicene strain release, and antiaromaticity. The role of antiaromaticity relief is further supported by efficient reductive closure of the less strained monohelicenes where the relief of antiaromaticity promotes the cyclization even when the strain is substantially reduced. The latter finding significantly expands the scope of this reductive alternative to the Scholl ring closure.