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1. Ruthenium Nitrosyl Porphyrins Coordinated with Aryloxides Containing Internal Hydrogen Bonds

   https://doi.org/10.1002/ejic.202400648  

   Warhausen, Adam_J; Zink, Jeremy_R; Ross, Bradley_J; Ramuglia, Anthony_R; Londoño‐Salazar, Jennifer; Shaw, Michael_J; Richter‐Addo, George_B (December 2024, European Journal of Inorganic Chemistry)

   Abstract The synthesis, characterization, and redox behavior of aryloxide complexes containing an increasing number of internal hydrogen bonds (OEP)Ru(NO)(OAr_xH) (OEP=octaethylporphyrinato dianion; x=0, 1, 2) are reported. These nitrosyl aryloxide compounds were characterized by X‐ray crystallography, IR and¹H NMR spectroscopy. The IR spectra displayed υ_NOfrequencies in the 1823–1843 cm⁻¹range with compounds possessing more internal hydrogen bonds demonstrating higher υ_NOfrequencies due to diminished π‐backdonation to the Ru−NO fragment. Comparison of the distinct υ_NHand δ_N−Hsignals in the IR and¹H NMR spectra of the free and complexed OAr_1H/OAr_2Hligands support the notion of additional electron density being removed via intramolecular hydrogen bonding. Results of DFT calculations on the (porphine)Ru(NO)(OAr_xH) models (porphine=unsubstituted porphyrin) reveal that the HOMOs of these complexes have significant axial ligand contributions, whereas the HOMOs of the five‐coordinate [(porphine)RuNO)]⁺cation resides mostly on the equatorial porphyrin macrocycle. The electrochemical results of these (OEP)Ru(NO)(OAr_xH) complexes in CH₂Cl₂reveal first oxidations that occur at increasingly positive potentials when more internal hydrogen bonds are present. Based on the DFT and preliminary IR spectroelectrochemical results, we propose that the electrooxidations result in eventual dissociation of the axial aryloxide ligands. 

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2. Cooperative activation of O–H and S–H bonds across the Co–P bond of an N-heterocyclic phosphido complex

   https://doi.org/10.1039/C8DT05052J  

   Poitras, Andrew M.; Bezpalko, Mark W.; Foxman, Bruce M.; Thomas, Christine M. (February 2019, Dalton Transactions)

   Metal–ligand cooperation has proven to be a viable concept for σ bond activation and catalysis, however there are few examples involving phosphorus as an active participant in bond cleavage. The reactivity of E–H bonds (E = S, O) across a metal–phosphorus bond of a cobalt( i ) center ligated by a tridenate N-heterocyclic phosphido (NHP − ) ligand with diphosphine sidearms, (PPP) − , has been explored. Addition of PhOH to (PPP)CoPMe 3 ( 1 ) cleanly affords (PP OPh P)Co(H)PMe 3 ( 2 ), in which the O–H bond was heterolytically cleaved across the M–P NHP bond. Addition of PhSH to 1 first generates (PP H P)Co(SPh)PMe 3 ( 3 ), which undergoes an intermolecular rearrangement to generate (PP SPh P)Co(H)PMe 3 ( 4 ) as the thermodynamic product. A comparison with a related platinum( ii ) system reveals the subtle effects that variations in metal intrinsic properties can have on metal–ligand bifunctional σ bond activation processes. 

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3. Doping and temperature evolutions of optical response of Sr3(Ir1-xRux)2O7

   https://doi.org/10.1038/s41598-020-79263-5  

   Ahn, Gihyeon; Schmehr, J. L.; Porter, Z.; Wilson, S. D.; Moon, S. J. (December 2020, Scientific Reports)

   null (Ed.)

   Abstract We report on optical spectroscopic study of the Sr 3 (Ir 1- x Ru x ) 2 O 7 system over a wide doping regime. We find that the changes in the electronic structure occur in the limited range of the concentration of Ru ions where the insulator–metal transition occurs. In the insulating regime, the electronic structure associated with the effective total angular momentum J eff  = 1/2 Mott state remains robust against Ru doping, indicating the localization of the doped holes. Upon entering the metallic regime, the Mott gap collapses and the Drude-like peak with strange metallic character appears. The evolution of the electronic structure registered in the optical data can be explained in terms of a percolative insulator–metal transition. The phonon spectra display anomalous doping evolution of the lineshapes. While the phonon modes of the compounds deep in the insulating and metallic regimes are almost symmetric, those of the semiconducting compound with x  = 0.34 in close proximity to the doping-driven insulator–metal transition show a pronounced asymmetry. The temperature evolution of the phonon modes of the x  = 0.34 compound reveals the asymmetry is enhanced in the antiferromagnetic state. We discuss roles of the S  = 1 spins of the Ru ions and charge excitations for the conspicuous lineshape asymmetry of the x  = 0.34 compound. 

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4. Diruthenium aryl compounds – tuning of electrochemical responses and solubility

   https://doi.org/10.1039/D1DT03957A  

   Miller-Clark, Lyndsy A.; Christ, Peter E.; Ren, Tong (January 2022, Dalton Transactions)

   Reported herein are the two new series of diruthenium aryl compounds: Ru 2 (DiMeOap) 4 (Ar) (1a–6a) (DiMeOap = 2-(3,5-dimethoxyanilino)pyridinate) and Ru 2 ( m - i PrOap) 4 (Ar) (1b–5b) ( m - i PrOap = 2-(3-iso-propoxyanilino)pyridinate), prepared through the lithium-halogen exchange reaction with a variety of aryl halides (Ar = C 6 H 4 -4-NMe 2 (1), C 6 H 4 -4- t Bu (2), C 6 H 4 -4-OMe (3), C 6 H 3 -3,5-(OMe) 2 (4), C 6 H 4 -4-CF 3 (5), C 6 H 5 (6)). The molecular structures of these compounds were established with X-ray diffraction studies. Additionally, these compounds were characterized using electronic absorption and voltammetric techniques. Compounds 1a–6a and 1b–5b are all in the Ru 2 5+ oxidation state, with a ground state configuration of σ 2 π 4 δ 2 (π*δ*) 3 ( S = 3/2). Use of the modified ap ligands (ap′) resulted in moderate increases of product yield when compared to the unsubstituted Ru 2 (ap) 4 (Ar) (ap = 2-anilinopyridinate) series. Comparisons of the electrochemical properties of 1a–6a and 1b–5b against the Ru 2 (ap′)Cl starting material reveals the addition of the aryl ligand cathodically shifted the Ru 2 6+/5+ oxidation and Ru 2 5+/4+ reduction potentials. These oxidation and reductions potentials are also strongly dependent on the p -substituent of the axial aryl ligands. 

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5. P-Alkynyl functionalized benzazaphospholes as transmetalating agents

   https://doi.org/10.1039/d0dt01367f  

   Zhou, Daniel Y.; Miura-Akagi, Preston M.; McCarty, Sierra M.; Guiles, Celeste H.; O'Donnell, Timothy J.; Yoshida, Wesley Y.; Krause, Colleen E.; Rheingold, Arnold L.; Hughes, Russell P.; Cain, Matthew F. (January 2021, Dalton Transactions)

   null (Ed.)

   Exposure of 10π-electron benzazaphosphole 1 to HCl, followed by nucleophilic substitution with the Grignard reagent BrMgCCPh afforded alkynyl functionalized 3 featuring an exocyclic –CC–Ph group with an elongated P–C bond (1.7932(19) Å). Stoichiometric experiments revealed that treatment of trans -Pd(PEt 3 ) 2 (Ar)( i ) (Ar = p -Me ( C ) or p -F ( D )) with 3 generated trans -Pd(PEt 3 ) 2 (Ar)(CCPh) (Ar = p -Me ( E ) or p -F ( F )), 5 , which is the result of ligand exchange between P–I byproduct 4 and C/D , and the reductively eliminated product (Ar–CC–Ph). Cyclic voltammetry studies showed and independent investigations confirmed 4 is also susceptible to redox processes including bimetallic oxidative addition to Pd(0) to give Pd( i ) dimer 6-Pd2-(P(t-Bu)3)2 and reduction to diphosphine 7 . During catalysis, we hypothesized that this unwanted reactivity could be circumvented by employing a source of fluoride as an additive. This was demonstrated by conducting a Sonogashira-type reaction between 1-iodotoluene and 3 in the presence of 10 mol% Na 2 PdCl 4 , 20 mol% P( t -Bu)Cy 2 , and 5 equiv. of tetramethylammonium fluoride (TMAF), resulting in turnover and the isolation of Ph–CC–( o -Tol) as the major product. 

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