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Abstract In a high‐resolution photoelectron imaging and theoretical study of the IrB3−cluster, two isomers were observed experimentally with electron affinities (EAs) of 1.3147(8) and 1.937(4) eV. Quantum calculations revealed two nearly degenerate isomers competing for the global minimum, both with a B3ring coordinated with the Ir atom. The isomer with the higher EA consists of a B3ring with a bridge‐bonded Ir atom (Cs,2A′), and the second isomer features a tetrahedral structure (C3v,2A1). The neutral tetrahedral structure was predicted to be considerably more stable than all other isomers. Chemical bonding analysis showed that the neutralC3visomer involves significant covalent Ir−B bonding and weak ionic bonding with charge transfer from B3to Ir, and can be viewed as an Ir–(η3‐B3+) complex. This study provides the first example of a boron‐to‐metal charge‐transfer complex and evidence of a π‐aromatic B3+ring coordinated to a transition metal.
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Observation of Transition‐Metal–Boron Triple Bonds in IrB 2 O − and ReB 2 O −
Abstract Multiple bonds between boron and transition metals are known in many borylene (:BR) complexes via metal dπ→BR back‐donation, despite the electron deficiency of boron. An electron‐precise metal–boron triple bond was first observed in BiB2O−[Bi≡B−B≡O]−in which both boron atoms can be viewed as sp‐hybridized and the [B−BO]−fragment is isoelectronic to a carbyne (CR). To search for the first electron‐precise transition‐metal‐boron triple‐bond species, we have produced IrB2O−and ReB2O−and investigated them by photoelectron spectroscopy and quantum‐chemical calculations. The results allow to elucidate the structures and bonding in the two clusters. We find IrB2O−has a closed‐shell bent structure (Cs,1A′) with BO−coordinated to an Ir≡B unit, (−OB)Ir≡B, whereas ReB2O−is linear (C∞v,3Σ−) with an electron‐precise Re≡B triple bond, [Re≡B−B≡O]−. The results suggest the intriguing possibility of synthesizing compounds with electron‐precise M≡B triple bonds analogous to classical carbyne systems.
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- Award ID(s):
- 1763380
- PAR ID:
- 10160286
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 59
- Issue:
- 35
- ISSN:
- 1433-7851
- Page Range / eLocation ID:
- p. 15260-15265
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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