Unexpected reversible pyrazine based methylation in a Ru(<scp>ii</scp>) complex bearing a pyrazin-2′-yl-1,2,4-triazolato ligand and its effect on acid/base and photophysical properties

Brennan, Claire; Draksharapu, Apparao; Browne, Wesley R.; McGarvey, John J.; Vos, Johannes G.; Pryce, Mary T.

doi:10.1039/c2dt31589k

Cited by 6 publications

(5 citation statements)

References 77 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This design strategy has been employed for a wide range of complexes, where protonation/deprotonation, interactions with a Lewis acid, or addition of an electrophile in the secondary sphere has led to significant rate enhancements in stoichiometric and catalytic processes (Figure ). ,− …”

Section: Protic Groups Remote From the Reactive Sitementioning

confidence: 99%

“…Alkylation of amine or imine nitrogen groups in the secondary sphere of Ru and Fe complexes increases the overall charge of the complex and thus the electrophilicity of the metal. ,,, For example, the reaction of Fe– and Ru–bMepi complexes with MeOTf converts the X-type amido ligand into a neutral L-type imino ligand (e.g., Figure ). ,, The enhanced electrophilicity can be characterized by voltammetry experiments, and the alkylated complex Fe(bMepi Me )(OTf) 2 exhibits an anodic shift of 390 mV relative to Fe(bMepi)(THF)(OTf).…”

Section: Protic Groups Remote From the Reactive Sitementioning

confidence: 99%

See 1 more Smart Citation

Hydrogen Transfer Catalysis beyond the Primary Coordination Sphere

Hale

Szymczak

2018

ACS Catal.

View full text Add to dashboard Cite

In this Perspective, we outline recent examples of homogeneous transition-metal hydrogen transfer catalysts for which functionality within the complex's outer coordination sphere influences the outcome of a reaction. Secondarysphere groups are often applied to hydrogen transfer reactions, but their specific role during catalysis is not always wellunderstood. New experimental and theoretical work details the complexity associated with predicting secondary-sphere interactions and therefore designing improved catalysts. This Perspective highlights examples of catalysts containing secondary-sphere groups that (1) accelerate a key turnoverlimiting step such as H 2 heterolysis or hydride transfer, (2) limit competing catalytic cycles, (3) prevent catalyst decomposition, and/or (4) provide access to new catalysts through postmetalation modifications. The examples described herein emphasize numerous roles of the secondary sphere in hydrogen transfer catalysis and illustrate how the optimal use of these interactions is predicated on the analyses of key reaction intermediates in a catalytic reaction.

show abstract

Section: Protic Groups Remote From the Reactive Sitementioning

confidence: 99%

Section: Protic Groups Remote From the Reactive Sitementioning

confidence: 99%

Hydrogen Transfer Catalysis beyond the Primary Coordination Sphere

Hale

Szymczak

2018

ACS Catal.

View full text Add to dashboard Cite

show abstract

“…A strategy based on the use of Lewis acids (LAs) is another potential option for reversibly modulating the spatial environment around metal centers that bear multifunctional ligands (Figure A, right). − The LA-mediated process can cause a substantial change in both the electronic state and spatial environment of the metal center due to the change in the number of ligands. This feature clearly distinguishes LA-mediated processes from LB-mediated ones as the latter commonly proceeds without changing the number of ligands.…”

Section: Introductionmentioning

confidence: 99%

Reversible Modulation of the Electronic and Spatial Environment around Ni(0) Centers Bearing Multifunctional Carbene Ligands with Triarylaluminum

Yamauchi,

Mondori,

Uetake

et al. 2023

J. Am. Chem. Soc.

View full text Add to dashboard Cite

Designing and modulating the electronic and spatial environments surrounding metal centers is a crucial issue in a wide range of chemistry fields that use organometallic compounds. Herein, we demonstrate a Lewis-acid-mediated reversible expansion, contraction, and transformation of the spatial environment surrounding nickel(0) centers that bear N-phosphine oxide-substituted N-heterocyclic carbenes (henceforth referred to as (S)PoxIms). Reaction between tetrahedral (syn-κ-C,O-(S)PoxIm)Ni(CO)2 and Al(C6F5)3 smoothly afforded heterobimetallic Ni/Al species such as trigonal-planar {κ-C-Ni(CO)2}(μ-anti-(S)PoxIm){κ-O-Al(C6F5)3} via a complexation-induced rotation of the N-phosphine oxide moieties, while the addition of 4-dimethylaminopyridine resulted in the quantitative regeneration of the former Ni complexes. The corresponding interconversion also occurred between (SPoxIm)Ni(η2:η2-diphenyldivinylsilane) and {κ-C-Ni(η2:η2-diene)}(μ-anti-SPoxIm){κ-O-Al(C6F5)3} via the coordination and dissociation of Al(C6F5)3. The shape and size of the space around the Ni(0) center was drastically changed through this Lewis-acid-mediated interconversion. Moreover, the multinuclear NMR, IR, and XAS analyses of the aforementioned carbonyl complexes clarified the details of the changes in the electronic states on the Ni centers; i.e., the electron delocalization was effectively enhanced among the Ni atom and CO ligands in the heterobimetallic Ni/Al species. The results presented in this work thus provide a strategy for reversibly modulating both the electronic and spatial environment of organometallic complexes, in addition to the well-accepted Lewis-base-mediated ligand-substitution methods.

show abstract

“…A large body of reports are available in the literature, particularly by the research groups of Rau 54,55 and Vos, 56,57 concerning the effect of solution acidity on the emission characteristics of polypyridine complexes of Ru(II) along with various azole-based ligands. However, studies performed with tridentate ligands are sparse compared with bidentate ligands.…”

Section: ■ Introductionmentioning

confidence: 99%

“…A large body of reports are available in the literature, particularly by the research groups of Rau , and Vos, , concerning the effect of solution acidity on the emission characteristics of polypyridine complexes of Ru(II) along with various azole-based ligands. However, studies performed with tridentate ligands are sparse compared with bidentate ligands. ,− A sizeable number of reports are also available from our group − as well as from the research groups of Rau, − Ye, − Fabrizzi, Lees, to name a few, on Ru(II)–polypyridine complexes coupled with azole functionalities for recognition of anions.…”

Section: Introductionmentioning

confidence: 99%

Exploitation of the Second Coordination Sphere to Promote Significant Increase of Room-Temperature Luminescence Lifetime and Anion Sensing in Ruthenium–Terpyridine Complexes

et al. 2021

View full text Add to dashboard Cite

This paper deals with the synthesis, characterization, and photophysical behaviors of three Ru(II)–terpyridine complexes derived from a terpyridyl-imidazole ligand (tpy-HImzPh 3 Me 2 ), wherein a terpyridine moiety has been coupled with a dimethylbenzil unit through a phenylimidazole spacer. The three complexes display strong emission at RT having excited-state lifetimes in the range of 2.3–43.7 ns, depending upon the co-ligand present and the solvents used. Temperature-dependent emission spectral measurements have demonstrated that the energy separation between emitting metal-to-ligand charge transfer state and non-emitting metal-centered state is increased relative to that of [Ru(tpy)2]2+. In contrast to our previously studied Ru(II) complexes containing similar terpyridyl-imidazole motif but differing by peripheral methyl groups, significant enhancement of RT emission intensity and quantum yield and remarkable increase of emission lifetime occur for the present complexes upon protonation of the imidazole nitrogen(s) with perchloric acid. Additionally, by exploiting imidazole NH motif(s), we have examined their anion recognition behaviors in organic and aqueous media. Interestingly, the complexes are capable of visually recognizing cyanide ions in aqueous medium up to the concentration limit of 10–8 M. Computational studies involving density functional theory (DFT) and time-dependent DFT methods have been carried out to obtain insights into their electronic structures and to help with the assignment of absorption and emission bands.

show abstract

Unexpected reversible pyrazine based methylation in a Ru(ii) complex bearing a pyrazin-2′-yl-1,2,4-triazolato ligand and its effect on acid/base and photophysical properties

Cited by 6 publications

References 77 publications

Hydrogen Transfer Catalysis beyond the Primary Coordination Sphere

Hydrogen Transfer Catalysis beyond the Primary Coordination Sphere

Reversible Modulation of the Electronic and Spatial Environment around Ni(0) Centers Bearing Multifunctional Carbene Ligands with Triarylaluminum

Exploitation of the Second Coordination Sphere to Promote Significant Increase of Room-Temperature Luminescence Lifetime and Anion Sensing in Ruthenium–Terpyridine Complexes

Contact Info

Product

Resources

About