Multiconfigurational Electronic Structure of Nickel Cross-Coupling Catalysts Revealed by X-ray Absorption Spectroscopy DOI Creative Commons

Kacie J. Nelson,

Nathanael P. Kazmierczak, David A. Cagan

et al.

The Journal of Physical Chemistry Letters, Journal Year: 2024, Volume and Issue: 16(1), P. 87 - 94

Published: Dec. 19, 2024

NiII 2,2'-bipyridine complexes are commonly invoked intermediates in metallaphotoredox cross-coupling reactions. Despite their ubiquity, design principles targeting improved catalytic performance remain underdetermined. A series of Ni(Rbpy)(R'Ar)Cl (R = MeOOC, t-Bu, R' CH3, CF3) were proposed to have multiconfigurational electronic structures on the basis multiconfigurational/multireference calculations, with significant mixing Ni → bpy metal-to-ligand charge transfer (MLCT) configurations into ground-state wave function. Here, K-edge and L2,3-edge X-ray absorption spectroscopies provide experimental support for highly covalent these complexes. The pre-edge intensity spectrum reflects Ni-aryl bonding. L3-edge spectral shape is dependent ligand functionalization, a feature reflecting MLCT character assigned using prior ab initio new semiempirical calculations. results suggest push/pull effects aryl/bpy ligands moderate changes electron density during multiredox reaction cycle.

Language: Английский

C–C and C–O Bond Formation Reactivity of Nickel Complexes Supported by the Pyridinophane MeN3C Ligand DOI Creative Commons
Jonathan G. Leung, Dae Young Bae,

Yusuff Moshood

et al.

Dalton Transactions, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

The pyridinophane ligands R N3CX (X = H, Br) are well-established scaffolds that facilitate and stabilize nickel oxidative addition complexes to the proximal C(aryl)–X bond.

Language: Английский

Citations

0
Cyclometallated Co(III) Complexes with Lowest-Energy Charge Transfer Excited States Accessible with Visible Light DOI
Spencer T. Burton,

Gyunhee Lee,

Curtis E. Moore

et al.

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: April 10, 2025

The Co(III) complexes, cis-[Co(ppy)2(L)]PF6, where ppy = 2-phenylpyridine and L bpy (2,2'-bipyridine; 1), phen (1,10-phenanthroline; 2), DAP (1,12-diazaperylene; 3), are reported their photophysical properties were investigated to evaluate potential as sensitizers for applications that include solar energy conversion schemes photoredox catalysis. Calculations show cyclometallation in the cis-[Co(ppy)2(L)]PF6 series affords strong Co(dπ)/ppy(π) orbital interactions result a Co/ppy(π*) highest occupied molecular (HOMO) lowest unoccupied (LUMO) localized on diimine ligand, L(π*). Complexes 1-3 exhibit relatively invariant oxidation potentials, whereas reduction event is dependent identity of L, consistent with theoretical predictions. For 3 broad → L(π*) metal/ligand-to-ligand charge transfer (ML-LCT) absorption band observed CH3CN maxima at 507 nm, extending beyond 600 nm. Upon excitation 1ML-LCT transition, transient features population 3ML-LCT excited state lifetimes, τ, 3.0 ps, 4.6 42 ps 1, 2 respectively observed. irradiation 505 able reduce methyl viologen (MV2+), an electron acceptor commonly photocatalytic schemes. To our knowledge, represents first heteroleptic complex combines ligand lowest-lying metal-to-ligand states undergo photoinduced low-energy green light. As such, structural design important step toward d6 photosensitizers based earth abundant metals.

Language: Английский

Citations

0
Bespoke All-in-one Metallaphotoredox Heterogeneous Catalysts for C-C Cross-Couplings DOI Creative Commons

Menglong Ma,

Xiaoyu Wang, Chengzhi Wang

et al.

Published: June 11, 2024

In synergistic catalysis, multiple catalysts or active sites work together to produce ‘the whole is greater than the sum of its parts’ effect. However, trilemma flexibility-stability-cost lies ahead multiunit heterogeneous catalyst. As complexity increases, catalytic efficiency tends be restricted. Here, we report a general method tailor modular metallaphotoredox catalysts. The dyes and molecular could flexibly connect with inexpensive carbon nitride via stable covalent bonds, like LEGO® games. Tunable visible-light absorption, high electron-hole separation steerable construction have been realized simultaneously, meanwhile electron transfer mechanism has clarified operando techniques. By precisely regulating coordination field single-atom sites, four different metallaphotoredox-enabled C-C cross-couplings compatible good cyclic stability (up 150 hours) anti-interference ability.

Language: Английский

Citations

1
Indole Nucleophile Triggers Mechanistic Divergence in Ni-Photoredox N–Arylation DOI Creative Commons

Kevin Liang,

Olivia Taylor,

Angie L. López

et al.

Published: June 25, 2024

This study presents a Ni-photoredox method for indole N-arylation, broadening the range of substrates to include indoles with unprotected C3-positions and base-sensitive groups. Through detailed mechanistic inquiries, Ni(I/III) mechanism was uncovered, distinct from those commonly proposed Ni-catalyzed amine, thiol, alcohol arylation, as well Ni(0/II/III) cycle identified amide arylation under almost identical conditions. The key finding is formation Ni(I) intermediate bearing nucleophile ligand prior oxidative addition, which rare carbon-heteroatom coupling has profound impact on reaction kinetics scope. pre-coordination renders more electron-rich intermediate, broadens scope by enabling fast reactivity even challenging aryl bromide substrates. Thus, this work highlights often-overlooked influence X-type ligands Ni addition rates illustrates yet another divergence in C–heteroatom couplings.

Language: Английский

Citations

1
Indole Nucleophile Triggers Mechanistic Divergence in Ni‐Photoredox N–Arylation DOI Open Access

Kevin Liang,

Olivia Taylor,

Angie L. López

et al.

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: unknown

Published: July 27, 2024

Abstract This study presents a Ni‐photoredox method for indole N ‐arylation, broadening the range of substrates to include indoles with unprotected C3‐positions and base‐sensitive groups. Through detailed mechanistic inquiries, Ni(I/III) mechanism was uncovered, distinct from those commonly proposed Ni‐catalyzed amine, thiol, alcohol arylation, as well Ni(0/II/III) cycle identified amide arylation under almost identical conditions. The key finding is formation Ni(I) intermediate bearing nucleophile ligand prior oxidative addition, which rare carbon‐heteroatom coupling has profound impact on reaction kinetics scope. pre‐coordination renders more electron‐rich intermediate, broadens scope by enabling fast reactivity even challenging aryl bromide substrates. Thus, this work highlights often‐overlooked influence X‐type ligands Ni addition rates illustrates yet another divergence in C‐heteroatom couplings.

Language: Английский

Citations

1
Ultrafast all-optical coherence of molecular electron spins in room-temperature water solution DOI
Erica Sutcliffe, Nathanael P. Kazmierczak, Ryan G. Hadt

et al.

Science, Journal Year: 2024, Volume and Issue: 386(6724), P. 888 - 892

Published: Nov. 7, 2024

The tunability and spatial precision of paramagnetic molecules makes them attractive for quantum sensing. However, usual microwave-based detection methods have poor temporal resolution, optical compatible with room-temperature solutions remained elusive. In this study, we utilized pump-probe polarization spectroscopy to initialize track electron spin coherence in a molecule. Designed efficiently couple spins light, aqueous potassium hexachloroiridate(IV) enabled few-picosecond free-induction decay at room temperature micromolar concentrations. Viscosity was found strongly vary decoherence lifetimes. This approach has improved the experimental time resolution by up five orders magnitude, making it possible observe molecular system that only exhibits below 25 kelvin traditional techniques.

Language: Английский

Citations

1
Multiconfigurational Electronic Structure of Nickel Cross-Coupling Catalysts Revealed by X-ray Absorption Spectroscopy DOI Creative Commons

Kacie J. Nelson,

Nathanael P. Kazmierczak, David A. Cagan

et al.

The Journal of Physical Chemistry Letters, Journal Year: 2024, Volume and Issue: 16(1), P. 87 - 94

Published: Dec. 19, 2024

NiII 2,2'-bipyridine complexes are commonly invoked intermediates in metallaphotoredox cross-coupling reactions. Despite their ubiquity, design principles targeting improved catalytic performance remain underdetermined. A series of Ni(Rbpy)(R'Ar)Cl (R = MeOOC, t-Bu, R' CH3, CF3) were proposed to have multiconfigurational electronic structures on the basis multiconfigurational/multireference calculations, with significant mixing Ni → bpy metal-to-ligand charge transfer (MLCT) configurations into ground-state wave function. Here, K-edge and L2,3-edge X-ray absorption spectroscopies provide experimental support for highly covalent these complexes. The pre-edge intensity spectrum reflects Ni-aryl bonding. L3-edge spectral shape is dependent ligand functionalization, a feature reflecting MLCT character assigned using prior ab initio new semiempirical calculations. results suggest push/pull effects aryl/bpy ligands moderate changes electron density during multiredox reaction cycle.

Language: Английский

Citations

1