Lohmiller Thomas, Spyra Can-Jerome, Dechert Sebastian, Demeshko Serhiy, Bill Eckhard, Schnegg Alexander, Meyer Franc
EPR4Energy Joint Lab, Department Spins in Energy Conversion and Quantum Information Science, Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 16, 12489 Berlin, Germany.
University of Göttingen, Institute of Inorganic Chemistry, Tamannstrasse 4, D-37077 Göttingen, Germany.
JACS Au. 2022 May 6;2(5):1134-1143. doi: 10.1021/jacsau.2c00139. eCollection 2022 May 23.
A unique type of Cu/O adduct with orthogonal (close to 90°) Cu-O-O-Cu arrangement has been proposed for initial stages of O binding at biological type III dicopper sites, and targeted ligand design has now allowed us to emulate such an adduct in a pyrazolate-based μη η-peroxodicopper(II) complex () with Cu-O-O-Cu torsion φ of 87°, coined intermediate. Full characterization of , including X-ray diffraction ( = 1.452 Å) and Raman spectroscopy (ν̃ = 807 cm), completes a series of closely related Cu/O intermediates featuring μη η-peroxodicopper(II) cores with φ ranging from 55° (, -peroxo ; Brinkmeier A., J. Am. Chem. Soc.2021, 143, 10361) via 87° (, type) up to 104° (, approaching -peroxo ; Kindermann N., Angew. Chem., Int. Ed.2015, 54, 1738). SQUID magnetometry revealed ferromagnetic interaction of the Cu ions and a triplet ( = 1) ground state in . Frequency-domain THz-EPR has been employed to quantitatively investigate the spin systems of and . Magnetic transitions within the triplet ground states confirmed their substantial zero-field splittings (ZFS) suggested by magnetometry. Formally forbidden triplet-to-singlet transitions at 56 () and 157 cm (), which are in agreement with the exchange coupling strengths inferred from SQUID data, are reported for the first time for coupled dicopper(II) complexes. Rigorous analysis by spin-Hamiltonian-based simulations attributed the corresponding nonzero transition probabilities and the ZFS to substantial antisymmetric (Dzyaloshinskii-Moriya) exchange and provided robust values and orientations for the , , and tensors. These interactions can be correlated with the Cu-O-O-Cu geometries, revealing a linear increase of with the Cu-O-O-Cu torsion and a strong linear decrease with the Cu-O-O angle. Relevance of the intermediate for O activation at type III dicopper sites and a potential role of antisymmetric exchange in the concomitant intersystem crossing are proposed.
一种具有正交（接近90°）Cu-O-O-Cu排列的独特类型的Cu/O加合物已被提出用于生物III型双铜位点上O结合的初始阶段，现在靶向配体设计使我们能够在基于吡唑酸盐的μη η-过氧双铜（II）配合物（）中模拟这样一种加合物，其Cu-O-O-Cu扭转角φ为87°，命名为 中间体。对 的全面表征，包括X射线衍射（ = 1.452 Å）和拉曼光谱（ν̃ = 807 cm），完成了一系列密切相关的以μη η-过氧双铜（II）为核心的Cu/O中间体，其φ范围从55°（，-过氧 ；布林克迈尔A.，《美国化学会志》2021年，143卷，10361页）到87°（， 型）再到104°（，接近-过氧 ；金德曼N.，《德国应用化学》2015年，54卷，1738页）。超导量子干涉仪磁力测定法揭示了Cu离子的铁磁相互作用以及 中的三重态（ = 1）基态。频域太赫兹电子顺磁共振已被用于定量研究 和 的自旋系统。三重态基态内的磁跃迁证实了磁力测定法所暗示的它们显著的零场分裂（ZFS）。对于耦合双铜（II）配合物，首次报道了在56（）和157 cm（）处形式上禁止的三重态到单重态跃迁，这与从超导量子干涉仪数据推断出的交换耦合强度 一致。基于自旋哈密顿量的模拟进行的严格分析将相应的非零跃迁概率和ZFS归因于大量反对称（Dzyaloshinskii-Moriya）交换，并为 、 和 张量提供了可靠的值和取向。这些相互作用可以与Cu-O-O-Cu几何结构相关联，揭示了 随Cu-O-O-Cu扭转的线性增加以及随Cu-O-O角度的强烈线性降低。提出了 中间体在III型双铜位点上O活化中的相关性以及反对称交换在伴随的系间窜越中的潜在作用。
