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1. Distinct Bimetallic Cooperativity Among Water Reduction Catalysts Containing [Co ^III Co ^III ], [Ni ^II Ni ^II ], and [Zn ^II Zn ^II ] Cores

   https://doi.org/10.1002/chem.202104426  

   Morgan, Fredricka; Schaugaard, Richard; Anderson, Dennis; Schlegel, H_Bernhard; Verani, Cláudio_N (March 2022, Chemistry – A European Journal)

   Abstract Three binuclear species [LCo^III₂(μ‐Pz)₂](ClO₄)₃(1), [LNi^II₂(CH₃OH)₂Cl₂]ClO₄(2), and [LZn^II₂Cl₂]PF₆(3) supported by the deprotonated form of the ligand 2,6‐bis[bis(2‐pyridylmethyl) amino‐methyl]‐4‐methylphenol were synthesized, structurally characterized as solids and in solution, and had their electrochemical and spectroscopic behavior established. Species1–3had their water reduction ability studied aiming to interrogate the possible cooperative catalytic activity between two neighboring metal centers. Species1and2reduced H₂O to H₂effectively at an applied potential of −1.6 V_Ag/AgCl, yielding turnover numbers of 2,820 and 2,290, respectively, after 30 minutes. Species3lacked activity and was used as a negative control to eliminate the possibility of ligand‐based catalysis. Pre‐ and post‐catalytic data gave evidence of the molecular nature of the process within the timeframe of the experiments. Species1showed structural, rather than electronic cooperativity, while species2displayed no obvious cooperativity. DFT methods complemented the experimental results determining plausible mechanisms. 

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2. Synthetic Metallodithiolato Ligands as Pendant Bases in [Fe ^I Fe ^I ], [Fe ^I [Fe(NO)] ^II ], and [(μ-H)Fe ^II Fe ^II ] Complexes

   https://doi.org/10.1021/acs.inorgchem.9b03409  

   Kariyawasam Pathirana, Kavindu Dilshan; Ghosh, Pokhraj; Hsieh, Chung-H.; Elrod, Lindy Chase; Bhuvanesh, Nattamai; Darensbourg, Donald J.; Darensbourg, Marcetta Y. (March 2020, Inorganic Chemistry)

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3. Charge transfer and slow magnetic relaxation in a series of cyano-bridged FeIII4MII2 (M = Fe ^II , Co ^II , Ni ^II ) molecules

   https://doi.org/10.1039/c8qi01245h  

   Wang, Jin-Hua; Vignesh, Kuduva R.; Zhao, Jia; Li, Zhao-Yang; Dunbar, Kim R. (February 2019, Inorganic Chemistry Frontiers)

   The synthesis, single-crystal structures and magnetic properties of three new cyano-bridged complexes [FeIII4MII2] (M = Fe II , Co II , Ni II ) are reported. Electronic absorption spectroscopy reveals the occurrence of intervalence charge transfer for [FeIII4FeII2]. Field-induced slow magnetic relaxation behavior is exhibited for [FeIII4CoII2] and [FeIII4NiII2] which originates from the ferromagnetic interactions between Fe III and M II spin centers of the square. 

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4. Encapsulation of tricopper cluster in a synthetic cryptand enables facile redox processes from Cu ^I Cu ^I Cu ^I to Cu ^II Cu ^II Cu ^II states

   https://doi.org/10.1039/D0SC05441K  

   Zhang, Weiyao; Moore, Curtis E.; Zhang, Shiyu (March 2021, Chemical Science)

   null (Ed.)

   One-pot reaction of tris(2-aminoethyl)amine (TREN), [Cu I (MeCN) 4 ]PF 6 , and paraformaldehyde affords a mixed-valent [ TREN4 Cu II Cu I Cu I (μ 3 -OH)](PF 6 ) 3 complex. The macrocyclic azacryptand TREN4 contains four TREN motifs, three of which provide a bowl-shape binding pocket for the [Cu 3 (μ 3 -OH)] 3+ core. The fourth TREN caps on top of the tricopper cluster to form a cryptand, imposing conformational constraints and preventing solvent interaction. Contrasting the limited redox capability of synthetic tricopper complexes reported so far, [ TREN4 Cu II Cu I Cu I (μ 3 -OH)](PF 6 ) 3 exhibits several reversible single-electron redox events. The distinct electrochemical behaviors of [ TREN4 Cu II Cu I Cu I (μ 3 -OH)](PF 6 ) 3 and its solvent-exposed analog [ TREN3 Cu II Cu II Cu II (μ 3 -O)](PF 6 ) 4 suggest that isolation of tricopper core in a cryptand enables facile electron transfer, allowing potential application of synthetic tricopper complexes as redox catalysts. Indeed, the fully reduced [ TREN4 Cu I Cu I Cu I (μ 3 -OH)](PF 6 ) 2 can reduce O 2 under acidic conditions. The geometric constraints provided by the cryptand are reminiscent of Nature's multicopper oxidases (MCOs). For the first time, a synthetic tricopper cluster was isolated and fully characterized at Cu I Cu I Cu I ( 4a ), Cu II Cu I Cu I ( 4b ), and Cu II Cu II Cu I ( 4c ) states, providing structural and spectroscopic models for many intermediates in MCOs. Fast electron transfer rates (10 5 to 10 6 M −1 s −1 ) were observed for both Cu I Cu I Cu I /Cu II Cu I Cu I and Cu II Cu I Cu I /Cu II Cu II Cu I redox couples, approaching the rapid electron transfer rates of copper sites in MCO. 

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5. Electronic Structures of Pd ^II Dimers

   https://doi.org/10.1021/ic902189g  

   Bercaw, John E.; Durrell, Alec C.; Gray, Harry B.; Green, Jennifer C.; Hazari, Nilay; Labinger, Jay A.; Winkler, Jay R. (February 2010, Inorganic Chemistry)