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1. N ₃ -Ligated nickel( ii ) diketonate complexes: synthesis, characterization and evaluation of O ₂ reactivity

   https://doi.org/10.1039/d0dt01338b  

   Elsberg, Josiah G.; Peterson, Austin; Fuller, Amy L.; Berreau, Lisa M. (January 2020, Dalton Transactions)

   Interest in O 2 -dependent aliphatic carbon–carbon (C–C) bond cleavage reactions of first row divalent metal diketonate complexes stems from the desire to further understand the reaction pathways of enzymes such as DKE1 and to extract information to develop applications in organic synthesis. A recent report of O 2 -dependent aliphatic C–C bond cleavage at ambient temperature in Ni( ii ) diketonate complexes supported by a tridentate nitrogen donor ligand [(MBBP)Ni(PhC(O)CHC(O)Ph)]Cl ( 7-Cl ; MBBP = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine) in the presence of NEt 3 spurred our interest in further examining the chemistry of such complexes. A series of new TERPY-ligated Ni( ii ) diketonate complexes of the general formula [(TERPY)Ni(R 2 -1,3-diketonate)]ClO 4 ( 1 : R = CH 3 ; 2 : R = C(CH 3 ) 3 ; 3 : R = Ph) was prepared under air and characterized using single crystal X-ray crystallography, elemental analysis, 1 H NMR, ESI-MS, FTIR, and UV-vis. Analysis of the reaction mixtures in which these complexes were generated using 1 H NMR and ESI-MS revealed the presence of both the desired diketonate complex and the bis-TERPY derivative [(TERPY) 2 Ni](ClO 4 ) 2 ( 4 ). Through selective crystallization 1–3 were isolated in analytically pure form. Analysis of reaction mixtures leading to the formation of the MBBP analogs [(MBBP)Ni(R 2 -1,3-diketonate)]X (X = ClO 4 : 5 : R = CH 3 ; 6 : R = C(CH 3 ) 3 ; 7-ClO4 : R = Ph; X = Cl: 7-Cl : R = Ph) using 1 H NMR and ESI-MS revealed the presence of [(MBBP) 2 Ni](ClO 4 ) 2 ( 8 ). Analysis of aerobic acetonitrile solutions of analytically pure 1–3 , 5 and 6 containing NEt 3 and in some cases H 2 O using 1 H NMR and UV-vis revealed evidence for the formation of additional bis-ligand complexes ( 4 and 8 ) but suggested no oxidative diketonate cleavage reactivity. Analysis of the organic products generated from 3 , 7-ClO4 and 7-Cl revealed unaltered dibenzoylmethane. Our results therefore indicate that N 3 -ligated Ni( ii ) complexes of unsubstituted diketonate ligands do not exhibit O 2 -dependent aliphatic C–C bond clevage at room temperature, including in the presence of NEt 3 and/or H 2 O. 

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2. Macrocyclic complexes of Fe( iii ) with mixed hydroxypropyl and phenolate or amide pendants as T ₁ MRI probes

   https://doi.org/10.1039/d3dt04013e  

   Kras, Elizabeth A; Cineus, Roy; Crawley, Matthew R; Morrow, Janet R (February 2024, Dalton Transactions)

   Fe(iii) macrocyclic complexes with mixed oxygen donor pendants are studied as T₁MRI probes. Complexes with a phenolate pendant are among the most promising and produce pH dependent relaxivity profiles consistent with proton exchange pathways. 

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3. 1,2-Azolylamidino ruthenium( ii ) complexes with DMSO ligands: electro- and photocatalysts for CO ₂ reduction

   https://doi.org/10.1039/D3DT01122D  

   Jennings, Murphy; Cuéllar, Elena; Rojo, Ariadna; Ferrero, Sergio; García-Herbosa, Gabriel; Nganga, John; Angeles-Boza, Alfredo M.; Martín-Alvarez, Jose M.; Miguel, Daniel; Villafañe, Fernando (November 2023, Dalton Transactions)

   Ru(ii) 1,2-azolylamidino-DMSO complexes are herein described. Their electrochemical behavior in CO₂media is consistent with CO₂electrocatalyzed reduction, whereas photocatalytic CO₂reduction experiments lead to CO and trace amounts of formate. 

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4. Evaluating electrochemical accessibility of 4f ⁿ 5d ¹ and 4f ⁿ⁺¹ Ln( ii ) ions in (C ₅ H ₄ SiMe ₃ ) ₃ Ln and (C ₅ Me ₄ H) ₃ Ln complexes

   https://doi.org/10.1039/D1DT02427B  

   Trinh, Michael T.; Wedal, Justin C.; Evans, William J. (October 2021, Dalton Transactions)

   The reduction potentials (reported vs. Fc + /Fc) for a series of Cp′ 3 Ln complexes (Cp′ = C 5 H 4 SiMe 3 , Ln = lanthanide) were determined via electrochemistry in THF with [ n Bu 4 N][BPh 4 ] as the supporting electrolyte. The Ln( iii )/Ln( ii ) reduction potentials for Ln = Eu, Yb, Sm, and Tm (−1.07 to −2.83 V) follow the expected trend for stability of 4f 7 , 4f 14 , 4f 6 , and 4f 13 Ln( ii ) ions, respectively. The reduction potentials for Ln = Pr, Nd, Gd, Tb, Dy, Ho, Er, and Lu, that form 4f n 5d 1 Ln( ii ) ions ( n = 2–14), fall in a narrow range of −2.95 V to −3.14 V. Only cathodic events were observed for La and Ce at −3.36 V and −3.43 V, respectively. The reduction potentials of the Ln( ii ) compounds [K(2.2.2-cryptand)][Cp′ 3 Ln] (Ln = Pr, Sm, Eu) match those of the Cp′ 3 Ln complexes. The reduction potentials of nine (C 5 Me 4 H) 3 Ln complexes were also studied and found to be 0.05–0.24 V more negative than those of the Cp′ 3 Ln compounds. 

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5. Theoretical insights into the vibrational spectra and chemical bonding of Ln( iii ) complexes with a tripodal N ₄ O ₃ ligand along the lanthanide series

   https://doi.org/10.1039/D4CP03677H  

   Machado, Francielle C; Quintano, Mateus; Santos-Jr, Carlos V; Carneiro_Neto, Albano N; Kraka, Elfi; Longo, Ricardo L; Moura_Jr, Renaldo T (January 2025, Physical Chemistry Chemical Physics)

   This study provides new theoretical insights into the vibrational spectra of Ln(iii) complexes, along the lanthanide series by utilizing the LModeAGen protocol and integrating cutting-edge topological ideas. 

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