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1. An Fe complex for ¹⁹ F magnetic resonance-based reversible redox sensing and multicolor imaging

   https://doi.org/10.1039/D2SC05222A  

   Kadakia, Rahul T.; Ryan, Raphael T.; Cooke, Daniel J.; Que, Emily L. (May 2023, Chemical Science)

   We report a first-in-class responsive, pentafluorosulfanyl (–SF 5 )-tagged 19 F MRI agent capable of reversibly detecting reducing environments via an Fe II/III redox couple. In the Fe III form, the agent displays no 19 F MR signal due to paramagnetic relaxation enhancement-induced signal broadening; however, upon rapid reduction to Fe II with one equivalent of cysteine, the agent displays a robust 19 F signal. Successive oxidation and reduction studies validate the reversibility of the agent. The –SF 5 tag in this agent enables ‘multicolor imaging’ in conjunction with sensors containing alternative fluorinated tags and this was demonstrated via simultaneous monitoring of the 19 F MR signal of this –SF 5 agent and a hypoxia-responsive agent containing a –CF 3 group. 

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2. A cationic gold-fluorenyl complex with a dative Au → C ⁺ bond: synthesis, structure, and carbophilic reactivity

   https://doi.org/10.1039/D2CC05436A  

   Litle, Elishua D.; Gabbaï, François P. (January 2023, Chemical Communications)

   Aiming to study the interaction of gold with the highly Lewis acidic fluorenyl cation, we synthesised ( o -[Ph 2 P(C 6 H 4 )Flu)AuCl(tht)][BF 4 ] ([2][BF 4 ]) and ( o -Ph 2 P(C 6 H 4 )Flu)AuCl 2 (3) (Flu = 9-fluorenyl) and found that the latter could be converted into [( o -Ph 2 P(C 6 H 4 )Flu)AuCl] + ([4] + ) upon treatment with NaBArF 24 (BArF 24 = B(3,5-C 6 H 3 (CF 3 ) 2 ) 4 ). [4] + , which has been isolated as a chloride-bridged dimer, readily catalyses the cycloisomerisation of 2-allyl-2-(2-propynyl)malonate. Computational results show that [4] + possesses a strong Au → C + bond and readily activates enynes. 

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3. Structural characterization and Hirshfeld surface analysis of 2-iodo-4-(pentafluoro-λ ⁶ -sulfanyl)benzonitrile

   https://doi.org/10.1107/S2056989020000365  

   González Espiet, Jean C.; Cintrón Cruz, Juan A.; Piñero Cruz, Dalice M. (February 2020, Acta Crystallographica Section E Crystallographic Communications)

   null (Ed.)

   The title compound, C 7 H 3 F 5 INS, a pentafluorosulfanyl (SF 5 ) containing arene, was synthesized from 4-(pentafluorosulfanyl)benzonitrile and lithium tetramethylpiperidide following a variation to the standard approach, which features simple and mild conditions that allow direct access to tri-substituted SF 5 intermediates that have not been demonstrated using previous methods. The molecule displays a planar geometry with the benzene ring in the same plane as its three substituents. It lies on a mirror plane perpendicular to [010] with the iodo, cyano, and the sulfur and axial fluorine atoms of the pentafluorosulfanyl substituent in the plane of the molecule. The equatorial F atoms have symmetry-related counterparts generated by the mirror plane. The pentafluorosulfanyl group exhibits a staggered fashion relative to the ring and the two hydrogen atoms ortho to the substituent. S—F bond lengths of the pentafluorosulfanyl group are unequal: the equatorial bond facing the iodo moiety has a longer distance [1.572 (3) Å] and wider angle compared to that facing the side of the molecules with two hydrogen atoms [1.561 (4) Å]. As expected, the axial S—F bond is the longest [1.582 (5) Å]. In the crystal, in-plane C—H...F and N...I interactions as well as out-of-plane F...C interactions are observed. According to the Hirshfeld analysis, the principal intermolecular contacts for the title compound are F...H (29.4%), F...I (15.8%), F...N (11.4%), F...F (6.0%), N...I (5.6%) and F...C (4.5%). 

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4. Synthesis of Ln ^II ‐in‐Cryptand Complexes by Chemical Reduction of Ln ^III ‐in‐Cryptand Precursors: Isolation of a Nd ^II ‐in‐Cryptand Complex

   https://doi.org/10.1002/anie.202006393  

   Huh, Daniel N.; Ciccone, Sierra R.; Bekoe, Samuel; Roy, Saswata; Ziller, Joseph W.; Furche, Filipp; Evans, William J. (June 2020, Angewandte Chemie International Edition)

   Abstract Lanthanide triflates have been used to incorporate Nd^IIIand Sm^IIIions into the 2.2.2‐cryptand ligand (crypt) to explore their reductive chemistry. The Ln(OTf)₃complexes (Ln=Nd, Sm; OTf=SO₃CF₃) react with crypt in THF to form the THF‐soluble complexes [Ln^III(crypt)(OTf)₂][OTf] with two triflates bound to the metal encapsulated in the crypt. Reduction of these Ln^III‐in‐crypt complexes using KC₈in THF forms the neutral Ln^II‐in‐crypt triflate complexes [Ln^II(crypt)(OTf)₂]. DFT calculations on [Nd^II(crypt)]²⁺], the first Nd^IIcryptand complex, assign a 4f⁴electron configuration to this ion. 

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5. Tetranuclear and trinuclear copper( i ) pyrazolates as catalysts in copper mediated azide–alkyne cycloadditions (CuAAC)

   https://doi.org/10.1039/d1dt04026j  

   Patterson, Monika R.; Dias, H. V. (December 2021, Dalton Transactions)

   Homoleptic, tetranuclear copper( i ) pyrazolates {[3,5-( t -Bu) 2 Pz]Cu} 4 , {[3-(CF 3 )-5-( t -Bu)Pz]Cu} 4 , and {[4-Br-3,5-( i -Pr) 2 Pz]Cu} 4 are excellent stand-alone catalysts for azide–alkyne cycloaddition reactions (CuAAC). This work demonstrates that a range of pyrazolates, including those with electron donating and electron-withdrawing groups to sterically demanding substituents on the pyrazolyl backbones, can serve as effective ligand supports on tetranuclear copper catalysts. However, in contrast to the tetramers and also highly fluorinated {[3,5-(CF 3 ) 2 Pz]Cu} 3 , trinuclear copper( i ) complexes such as {[3,5-( i -Pr) 2 Pz]Cu} 3 and {[3-(CF 3 )-5-(CH 3 )Pz]Cu} 3 supported by relatively electron rich pyrazolates display poor catalytic activity in CuAAC. The behavior and degree of aggregation of several of these copper( i ) pyrazolates in solution were examined using vapor pressure osmometry. Copper( i ) complexes such as {[3,5-(CF 3 ) 2 Pz]Cu} 3 and {[3-(CF 3 )-5-( t -Bu)Pz]Cu} 4 with electron withdrawing pyrazolates were found to break up in solution to different degrees producing smaller aggregates while those such as {[3,5-( i -Pr) 2 Pz]Cu} 3 and {[3,5-( t -Bu) 2 Pz]Cu} 4 with electron rich pyrazolates remain intact. In addition, kinetic experiments were performed to understand the unusual activity of tetranuclear copper( i ) pyrazolate systems. 

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