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1. First Structurally Characterized Tricyanomanganate(III) and its Magnetic {Mn ^III ₂ M ^II ₂ } Complexes (M ^II = Mn, Ni)

   https://doi.org/10.1021/ic1006605  

   Tang, Minao; Li, Dongfeng; Mallik, Uma Prasad; Withers, Jeffrey R.; Brauer, Shari; Rhodes, Michael R.; Clérac, Rodolphe; Yee, Gordon T.; Whangbo, Myung-Hwan; Holmes, Stephen M. (June 2010, Inorganic Chemistry)
2. Structural and Magnetic Variations in a Family of Isoskeletal, Oximate-Bridged {Mn ^IV ₂ M ^III } Complexes (M ^III =Mn, Gd, Dy)

   https://doi.org/10.1002/chem.201706098  

   Alaimo, Alysha A.; Worrell, Anne; Gupta, Sayak Das; Abboud, Khalil A.; Lampropoulos, Christos; Christou, George; Stamatatos, Theocharis C. (February 2018, Chemistry - A European Journal)
3. A Geometrically Frustrated Family of M ^II M ^III F ₅ (H ₂ O) ₂ Mixed–Metal Fluorides with Complex Magnetic Interactions

   https://doi.org/10.1021/acs.inorgchem.1c01889  

   Keerthisinghe, Navindra; Berseneva, Anna A.; Klepov, Vladislav V.; Morrison, Gregory; zur Loye, Hans-Conrad (September 2021, Inorganic Chemistry)
4. 10 ⁶ -fold faster C–H bond hydroxylation by a Co ^III,IV ₂ (µ-O) ₂ complex [via a Co ^III ₂ (µ-O)(µ-OH) intermediate] versus its Fe ^III Fe ^IV analog

   https://doi.org/10.1073/pnas.2307950120  

   Li, Yan; Abelson, Chase; Que, Lawrence; Wang, Dong (December 2023, Proceedings of the National Academy of Sciences)

   The hydroxylation of C–H bonds can be carried out by the high-valent Co^III,IV₂(µ-O)₂complex2asupported by the tetradentate tris(2-pyridylmethyl)amine ligand via a Co^III₂(µ-O)(µ-OH) intermediate (3a). Complex3acan be independently generated either by H-atom transfer (HAT) in the reaction of2awith phenols as the H-atom donor or protonation of its conjugate base, the Co^III₂(µ-O)₂complex1a. Resonance Raman spectra of these three complexes reveal oxygen-isotope-sensitive vibrations at 560 to 590 cm⁻¹associated with the symmetric Co–O–Co stretching mode of the Co₂O₂diamond core. Together with a Co•••Co distance of 2.78(2) Å previously identified for1aand2aby Extended X-ray Absorption Fine Structure (EXAFS) analysis, these results provide solid evidence for their “diamond core” structural assignments. The independent generation of3aallows us to investigate HAT reactions of2awith phenols in detail, measure the redox potential and pK_aof the system, and calculate the O–H bond strength (D_O–H) of3ato shed light on the C–H bond activation reactivity of2a. Complex3ais found to be able to transfer its hydroxyl ligand onto the trityl radical to form the hydroxylated product, representing a direct experimental observation of such a reaction by a dinuclear cobalt complex. Surprisingly, reactivity comparisons reveal2ato be 10⁶-fold more reactive in oxidizing hydrocarbon C–H bonds than corresponding Fe^III,IV₂(µ-O)₂and Mn^III,IV₂(µ-O)₂analogs, an unexpected outcome that raises the prospects for using Co^III,IV₂(µ-O)₂species to oxidize alkane C–H bonds. 

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5. Ultraviolet Excitation of M-O ₂ (M = Phenalenone, Fluorenone, Pyridine, & Acridine) Complexes Resulting in ¹ O ₂

   https://doi.org/10.1021/acs.jpca.4c00143  

   Parsons, Bradley F.; Hulce, Martin R.; Ackerman, John R.; Reardon, Kylie A.; Pappas, Emerson S.; Kettler, Lauren E. (April 2024, The Journal of Physical Chemistry A)

   In our experiment, a trace amount of an organic molecule (M = 1H-phenalen-1-one, 9-fluorenone, pyridine, or acridine) was seeded into a gas mix consisting of 3% O₂ with a rare gas buffer (He or Ar) and then supersonically expanded. We excited the resulting molecular beam with ultraviolet light at either 355 nm (1H-phenalen-1-one, 9-fluorenone, or acridine) or 266 nm (pyridine) and used resonance enhanced multiphoton ionization (REMPI) spectroscopy to probe for formation of O₂ in the a ¹Δ_g state, ¹O₂. For all systems, the REMPI spectra demonstrates that ultraviolet excitation results in formation of ¹O₂ and the oxygen product is confirmed to be in the ground vibrational state and with an effective rotational temperature below 80 K. We then recorded the velocity map ion image of the ¹O₂ product. From the ion images we determined the center-of-mass translational energy distribution, P(E_T), assuming photodissociation of a bimolecular M-O₂ complex. We also report results from electronic structure calculations that allow for a determination of the M-O₂ ground state binding energy. We use the complex binding energy, the energy to form ¹O₂, and the adiabatic triplet energy for each organic molecule to determine the available energy following photodissociation. For dissociation of a bimolecular complex, this available energy may be partitioned into either center-of-mass recoil or internal degrees of freedom of the organic moiety. We use the available energy to generate a Prior distribution, which predicts statistical energy partitioning during dissociation. For low available energies, less than 0.2 eV, we find the statistical prediction is in reasonable agreement with the experimental observations. However, at higher available energies the experimental distribution is biased to lower center-of-mass kinetic energies compared with the statistical prediction, which suggests the complex undergoes vibrational predissociation. 

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