Abstract
The authors report the structure, reactivity, and catalytic utility of a triiridium complex, [Ir3H6(μ3-H)(PN)3]2+ (2-H, PN = (2-pyridyl)CH2PBut2). Despite its unusual stability to unsaturated organics, electrophiles, and even CF3SO3D, they find that complex 2-H catalyzes hydrogenation of CO2 to formate (TONIr = 9600) and reverse formic acid dehydrogenation (TONIr = 54 400). The hydrogenation operates via a reactive intermediate [Ir3H4(μ-H)4(PN)3]+ (5). Neutron crystallography and DFT-supported neutron vibrational spectroscopy of 2-H reveal Ir─H bond lengths and elucidate the vibration modes within the Ir3H7 core. Stoichiometric oxidation of 2-H produces four classes of iridium complexes of varied nuclearity and hydride structure: tetra- and pentanuclear clusters [Ir3H6(μ3-AuPPh3)(PN)3]2+ (2-Au) and [Ag{Ir2H4(μ-OAc)(PN)2}2]3+ (6) are generated using AuPPh3+ and AgOAc, respectively. Further oxidation to class [Ir2H3(μ-X)2(PN)2]+ is possible with AgOAc, Hg(OAc)2, or I2. Finally, a TEMPO/HCl system completely oxidizes the hydrides and gives [Ir2Cl4(μ-Cl)2(PN)2] (11).
| Original language | English |
|---|---|
| Article number | e202501943 |
| Journal | Angewandte Chemie - International Edition |
| Volume | 64 |
| Issue number | 21 |
| DOIs | |
| State | Published - May 19 2025 |
Funding
This work is sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (DE-EE-0011096). NIST contributed to performing this work. The authors thank the NSF (CHE-2018740, DBI-0821671, CHE-0840366), the NIH (S10 RR25432), and the USC Research and Innovation Instrumentation Awards for analytical equipment. Single-crystal neutron diffraction and vibrational spectroscopy measurements performed on TOPAZ and VISION beamlines used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory (ORNL). Computing resources were made available through the VirtuES and the ICE-MAN projects, funded by the Laboratory Directed Research and Development program and Compute and Data Environment for Science (CADES) at ORNL. X.W. acknowledges research sponsorship from the Laboratory Directed Research and Development Program at ORNL, managed by UT-Battelle, LLC, for the U.S. DOE. The authors are grateful to Dr. William Richards (USC), Juan Pablo De Los Rios (USC), and Dr. Thomas Saal (USC) for help with analytical equipment, and Dr. John Gordon (Brookhaven) for insightful discussions. Fellowship assistance from the Arnold and Mabel Beckman Foundation (A.J.C.) and NSF REU award CHE-1757942 (J.K.) is gratefully acknowledged. R.A.K. appreciates support from the U.S. DOE Office of Energy Efficiency and Renewable Energy (EERE), Hydrogen and Fuel Cell Technologies Office (contract no. DE-AC36-8GO28308) to the National Renewable Energy Laboratory (NREL). Certain commercial equipment, instruments, or materials are identified in this document. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the products identified are necessarily the best available for the purpose. This work is sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (DE‐EE‐0011096). NIST contributed to performing this work. The authors thank the NSF (CHE‐2018740, DBI‐0821671, CHE‐0840366), the NIH (S10 RR25432), and the USC Research and Innovation Instrumentation Awards for analytical equipment. Single‐crystal neutron diffraction and vibrational spectroscopy measurements performed on TOPAZ and VISION beamlines used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory (ORNL). Computing resources were made available through the VirtuES and the ICE‐MAN projects, funded by the Laboratory Directed Research and Development program and Compute and Data Environment for Science (CADES) at ORNL. X.W. acknowledges research sponsorship from the Laboratory Directed Research and Development Program at ORNL, managed by UT‐Battelle, LLC, for the U.S. DOE. The authors are grateful to Dr. William Richards (USC), Juan Pablo De Los Rios (USC), and Dr. Thomas Saal (USC) for help with analytical equipment, and Dr. John Gordon (Brookhaven) for insightful discussions. Fellowship assistance from the Arnold and Mabel Beckman Foundation (A.J.C.) and NSF REU award CHE‐1757942 (J.K.) is gratefully acknowledged. R.A.K. appreciates support from the U.S. DOE Office of Energy Efficiency and Renewable Energy (EERE), Hydrogen and Fuel Cell Technologies Office (contract no. DE‐AC36‐8GO28308) to the National Renewable Energy Laboratory (NREL). Certain commercial equipment, instruments, or materials are identified in this document. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the products identified are necessarily the best available for the purpose.
Keywords
- Catalysis
- Formate
- Heterometallic cluster
- Metal hydride
- Oxidation