FY2020 Annual Report
Coordination Chemistry and Catalysis Unit
Assistant Professor Julia Khusnutdinova
During FY2020, we succeeded in publishing our key findings in several directions pursued by our group. In particular, we reported several examples of metal-metal cooperative reactivity in organometallic multimetallic complexes, in particular, related to C-H bond activation, transmetalation and C-C bond coupling. In addition, we reported Ru-catalyzed alcohol dehydrogenation and Mn-catalyzed alkene hydrogenation by utilizing ligands capable of secondary coordination sphere interactions or metal-ligand cooperative reactivity. Importantly, we also published our new findings regarding mechanoluminscent Cu complexes in crystal state and in polymers that may be used as a method of stress detection in polymer materials.
- Dr. Ayumu Karimata, Postdoctoral Scholar
- Dr. Govindarajan Ramadoss, Postdoctoral Scholar
- Dr. Yutao He, Postdoctoral Scholar
- Dr. Dilip Pandey, Postdoctoral Scholar
- Sebastien Lapointe, Graduate Student
- Shubham Deolka, Graduate Student
- Hoan Dinh, Graduate Student
- Kyoko Chinen, Research Unit Administrator
- Type of collaboration: DFT calculations and mechanistic studies of multimetallic complexes
- Researchers: Dr. Shrinwantu Pal, Professor Kyoko Nozaki, University of Tokyo
- Type of collaboration: DFT and MD calculations of mechanisms related to Sonogashira coupling
- Researchers: Dr. Aleix Comas-Vives, Professor Agusti Lledós. Universitat Autònoma de Barcelona
3. Activities and Findings
3.1. Multimetallic Pd/Cu and Pt/Cu complexes and their reactivity in metal-metal cooperative bond activation
Cooperation between two different metals plays an important role in many catalytic reactions, such as the C−C cross‐coupling reactions. In particular, in Sonogashira coupling, an interaction between the Pd and Cu centers is proposed in the transmetalation step. Although several model Pd/Cu complexes have been reported as structural models, there is currently a lack of functional models that could demonstrate alkyne activation and C-C bond coupling in bimetallic Pd/Cu complexes. We reported a new ligand-driven aproach to the synthesis of heteromultimetallic Pd/Cu assemblies as a tool to study metal–metal cooperativity. Using naphthyridinone-based ligand framework, we synthesized Pd/Cu multimetallic assemblies that show reactivity in alkyne activation via Pd/Cu cooperation. Moreover, the same complexes further react with phosphines leading to mild C-C bond activation. The combination of experimental and theoretical studies demonstrated that ligand-controlled coordination geometry and the presence of close metal-metal distances play important role in the transmetalation step.
We also develop a different ligand scaffold featuring soft-hard coordination sites which stabilizes Pt/Cu organometallic complexes with Me, aryl and acetylide bridging ligands. Using these complexes, we demonstrated that the close proximity of Cu to Pt center alters the reactivity of organometallic Pt complexes leading to selective transmetalation of tetraarylborate salts, increased stability towards rollover cyclometalation, and facile activation of alkynes. DFT calculations performed in collaboration with Dr. Pal and Prof. Nozaki showed that Cu center acts as a docking site for alkyne coordinating, while activating its terminal C-H bond.
3.2. Ru and Mn-catalyzed hydrogenation and dehydrogenation reactions
Using napththyridinone-substituted phosphine ligand, we synthesized Ru complexes and studied their reactivity with water and alcohol. This ligand demonstrates a dual reactivity mode and can be deprotonated at two sites: an NH proton of naphthyridinone and a methylene arm attached to the phosphine. The derived Ru complexes show catalytic activity in acceptorless dehydrogenation of primary alcohols to aldehydes, although the turnover numbers remain limited.
We also developed a Mn catalyst supported by picolylphosphine ligand that was found to be a competent catalyst for alkene hydrogenation. Alkene hydrogenation catalysis is typically limited to precious metal catalysts, with only one previous example reported for manganese. Combined experimental and theoretical studies show that deprotonation of the methylene arm likely plays a crucial role in enabling this reactivity.
3.3. Mechanoluminescence of Cu complexes in crystal state and polymers
Triboluminescent materials play important role in developing "smart" materials, stress sensors and conversion of mechanical energy to light. Among known triboluminescent metal complexes, europium-based materials remain predominant, while examples of inexpensive Cu complexes remain limited. We found a new family of triboluminescent Cu complexes that demonstrate light emission in response to mechanical action in crystalline state and in rigid polymer films.
1. Vojkovsky, T.; Deolka, S.; Stepanova, S.; Roy, M. C.; Khaskin, E., Catalytic Sulfone Upgrading Reaction with Alcohols via Ru(II). ACS Catalysis 2020, 10 (12), 6810-6815.
2. Deolka, S.; Rivada-Wheelaghan, O.; Aristizábal, S. L.; Fayzullin, R. R.; Pal, S.; Nozaki, K.; Khaskin, E.; Khusnutdinova, J. R., Metal–metal cooperative bond activation by heterobimetallic alkyl, aryl, and acetylide PtII/CuI complexes. Chemical Science 2020, 11 (21), 5494-5502. DOI: 10.1039/d0sc00646g
3. Gallardo-Villagrán, M.; Rivada-Wheelaghan, O.; Rahaman, S. M. W.; Fayzullin, R. R.; Khusnutdinova, J. R., Proton-responsive naphthyridinone-based RuII complexes and their reactivity with water and alcohols. Dalton Transactions 2020, 49 (36), 12756-12766. DOI: 10.1039/d0dt02505d
4. Karimata, A.; Patil, P. H.; Fayzullin, R. R.; Khaskin, E.; Lapointe, S.; Khusnutdinova, J. R., Triboluminescence of a new family of CuI–NHC complexes in crystalline solid and in amorphous polymer films. Chemical Science 2020, 11 (39), 10814-10820. DOI: 10.1039/d0sc04442c
5. Rivada-Wheelaghan, O.; Comas-Vives, A.; Fayzullin, R. R.; Lledós, A.; Khusnutdinova, J. R., Dynamic PdII/CuI Multimetallic Assemblies as Molecular Models to Study Metal–Metal Cooperation in Sonogashira Coupling. Chemistry – A European Journal 2020, 26 (53), 12168-12179. DOI: 10.1002/chem.202002013
6. Rahaman, S. M. W.; Pandey, D. K.; Rivada-Wheelaghan, O.; Dubey, A.; Fayzullin, R. R.; Khusnutdinova, J. R., Hydrogenation of Alkenes Catalyzed by a Non-pincer Mn Complex. ChemCatChem 2020, 12 (23), 5912-5918. DOI/10.1002/cctc.202001158
4.2 Books and other one-time publications
Nothing to report
4.3 Oral and Poster Presentations
1. Deolka, S., Rivada-Wheelaghan, O., Ramadoss, G., Khaskin, E., & Khusnutdinova, J., Organometallic reactivity of heteromultimetallic Pd/Cucomplexes: bimetallic activation and the role ofunsymmetrical ligand scaffolds, in The 70th Conference of Japan Society of Coordination Chemistry, Online, 2020.9.28
2. He, Y.-T., Sarbajna, A., Karimata, A., Dinh, H. M., Gladkovskaya, O., Rahaman, S. M. W., Khaskin, E., Lapointe, S., Fayzullin, R. R., & Khusnutdinova, J., Manganese-Complex Mediated C-C Bond and C-X Bond Formation, in The 70th Conference of Japan Society of Coordination Chemistry, Online, 2020.9.29
3. Karimata, A., Patil, P., Fayzullin, R. R., Khaskin, E., Lapointe, S., & Khusnutdinova, J., Triboluminescence of pyridinophane CuI(NHC)complexes in crystals and amorphous polymers, in The 70th Conference of Japan Society of Coordination Chemistry, Online, 2020.9.28
4. Dinh, H. M., Garcia-Roca, A., Pruchyathamkorn, J., Gridneva, T., & Khusnutdinova, J., Single and double dearomatization of pyridine in N,S-donor pyridinophane metal complexes, in The 70th Conference of Japan Society of Coordination Chemistry, Online, 2020.9.30
5. Karimata, A., Patil, P.; Fayzullin, R. R., Khaskin, E., Lapointe, S. & Khusnutdinova, J., Triboluminescence of pyridinophane copper complexes in crystals and polymers, in The 101st CSJ Annual Meeting 2021: Online, 2021.3.20
6. Deolka, S., Rivada-Wheelaghan, O., Ramadoss, G., Khaskin, E. & Khusnutdinova, J. Heteropolymetallic Pd/Cu and Pt/Cu for metal-metal cooperative bond activation, in The 101st CSJ Annual Meeting 2021, Online, 2021.3.22
7. Khusnutdinova, J. R.; Karimata, A. Invited talk at IEICE (Institute of Electronics, Information and Communication Engineers) General Conference: "Using tribo- and photoluminescent Cu complexes to detect mechanical stress in polymers". Online, 2021.3.11
5. Intellectual Property Rights and Other Specific Achievements
1. Provisional patent, Japan, Application/Provisional number 2020-103434, J. R. Khusnutdinova, A. Karimata, “Mechanoresponsive polymers containing photoluminescent copper(I)-containing cross-linkers”.
2. Provisional patent, Japan, Application/Provisional number 2020-120094, J. R. Khusnutdinova, A. Karimata, P. H. Patil, “Triboluminescence of Cu-NHC complexes in solid state and in polymer films”.
6. Meetings and Events
"Metal-Ligand Cooperation for Bond Activation" Symposium at PACIFICHEM co-organized by PI is currently postponed to 2021.
Dr. Sébastien Lapointe graduated from our group in August 2020 with a Ph.D. degree. The title of his Ph.D. thesis is "Nickel Complexes of New Electron-Rich, Sterically-Hindered PNP Pincer Ligands".