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We report a high-resolution photoelectron imaging and theoretical study of the IrB3‾ cluster. Two isomers are observed experimentally with electron affinities (EAs) of 1.3147(8) eV and 1.937(4) eV. Quantum calculations reveal two nearly degenerate isomers competing for the global minimum, both with a B3 ring coordinated with the Ir atom. One of the isomers consists of a B3 ring with a bridge-bonded Ir (Cs, 2A), which has the higher EA; and the second isomer features a tetrahedral structure (C3v, 2A1), which has the lower EA. The neutral tetrahedral structure is predicted to be overwhelmingly more stable than all other isomers. Chemical bonding analyses show that the neutral C3v isomer involves significant covalent Ir–B bonding and weak ionic bonding with charge transfers from B3 to Ir, which can be viewed as an Ir‾(η3-B3+) complex. The current study reports the first example of a boron-to-metal charge transfer complex and provides evidence of a π-aromatic B3+ ring coordinated to a transition metal.
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Probing copper-boron interactions in the Cu 2 B 8 − bimetallic cluster
Borophenes are atom-thin boron layers that can be grown on coinage metal substrates and have become an important class of synthetic 2D nanomaterials. The interactions between boron and substrates are critical to understand the growth mechanisms of borophenes. Here, we report an investigation of copper-boron interactions in the Cu 2 B 8 − bimetallic cluster using photoelectron spectroscopy and quantum chemical calculations. Well-resolved photoelectron spectra are obtained at several photon energies and are combined with theoretical calculations to elucidate the structures and bonding of Cu 2 B 8 − . Global minimum searches reveal that Cu 2 B 8 − consists of a Cu 2 dimer atop a B 8 molecular wheel with a long Cu–Cu bond length close to that in Cu 2 + . Chemical bonding analyses indicate that there is clear charge transfer from Cu 2 to B 8 , and the Cu 2 B 8 − cluster can be viewed as a [Cu 2 + ]-borozene complex, [Cu 2 + ][B 8 2– ]. In the neutral cluster, no Cu–Cu bond exists and Cu 2 B 8 consists of two Cu + centers interacting with doubly aromatic B 8 2− borozene. The charge transfer interactions between Cu and boron in the Cu 2 B 8 − cluster are analogous to charge transfer from the copper substrate to the first borophene layer recently reported to be critical in the growth of bilayer borophenes on a Cu(111) substrate.
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- Award ID(s):
- 2053541
- PAR ID:
- 10402313
- Date Published:
- Journal Name:
- Journal of Vacuum Science & Technology A
- Volume:
- 40
- Issue:
- 4
- ISSN:
- 0734-2101
- Page Range / eLocation ID:
- 042201
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1116/6.0001833
