Activation and Transformation of Methane on Boron-Doped Cobalt Oxide Cluster Cations CoBO2. Inorg Chem 2024;63:1537-1542. [PMID: 38181068 DOI: 10.1021/acs.inorgchem.3c03112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The cleavage of inert C-H bonds in methane at room temperature and the subsequent conversion into value-added products are quite challenging. Herein, the reactivity of boron-doped cobalt oxide cluster cations CoBO2+ toward methane under thermal collision conditions was studied by mass spectrometry experiments and quantum-chemical calculations. In this reaction, one H atom and the CH3 unit of methane were transformed separately to generate the product metaboric acid (HBO2) and one CoCH3+ ion, respectively. Theoretical calculations strongly suggest that a catalytic cycle can be completed by the recovery of CoBO2+ through the reaction of CoCH3+ with sodium perborate (NaBO3), and this reaction generates sodium methoxide (CH3ONa) as the other value-added product. This study shows that boron-doped cobalt oxide species are highly reactive to facilitate thermal methane transformation and may open a way to develop more effective approaches for methane (CH4) activation and conversion under mild conditions.

Ionization Energies and Cationic Bond Dissociation Energies of RuB, RhB, OsB, IrB, and PtB

Two-photon ionization thresholds of RuB, RhB, OsB, IrB, and PtB have been measured using resonant two-photon ionization spectroscopy in a jet-cooled molecular beam and have been used to derive the adiabatic ionization energies of these molecules. From the measured two-photon ionization thresholds, IE(RuB) = 7.879(9) eV, IE(RhB) = 8.234(10) eV, IE(OsB) = 7.955(9) eV, IE(IrB) = 8.301(15) eV, and IE(PtB) = 8.524(10) eV have been assigned. By employing a thermochemical cycle, cationic bond dissociation energies of these molecules have also been derived, giving D0(Ru+-B) = 4.297(9) eV, D0(Rh+-B) = 4.477(10) eV, D0(Os-B+) = 4.721(9) eV, D0(Ir-B+) = 4.925(18) eV, and D0(Pt-B+) = 5.009(10) eV. The electronic structure of the resulting cationic transition metal monoborides (MB+) have been elucidated using quantum chemical calculations. Periodic trends of the MB+ molecules and comparisons to their neutral counterparts are discussed. The possibility of quadruple chemical bonds in all of these cationic transition metal monoborides is also discussed.

Consecutive methane activation mediated by single metal boride cluster anions NbB4. Phys Chem Chem Phys 2021;23:12592-12599. [PMID: 34047332 DOI: 10.1039/d1cp01418h]

Cleavage of all C-H bonds in two methane molecules by gas-phase cluster ions at room temperature is a challenging task. Herein, mass spectrometry and quantum chemical calculations have been used to identify one single metal boride cluster anions NbB4- that can activate eight C-H bonds in two methane molecules and release one H2 molecule each time under thermal collision conditions. In these consecutive reactions, the loaded Nb atoms and the support B4 units play different roles but act synergistically to activate CH4, which is responsible for the interesting reactivity of NbB4-. Moreover, there are some mechanistic differences in these two reactions, including the mechanisms for the first C-H bond activation steps, dihydrogen desorption sites, and major electron donors. This study shows that non-noble metal boride species are reactive enough to facilitate thermal C-H bond cleavages, and boron-based materials may be one kind of potential support material facilitating surface hydrogen transport.