Many binuclear nickel complexes have NiNi distances suggesting NiNi covalent bonds, including lantern‐type complexes with bridging bidentate ligands. This DFT study treats tetragonal, trigonal, and digonal lantern‐type complexes with the formamidinate, guanidinate, and formate ligands, besides some others. Formal bond orders (ranging from zero to two) are assigned to all the NiNi bonds on the basis of MO occupancy considerations. A VB‐based electron counting approach assigns plausible resonance structures to the dinickel cores. Model tetragonal complexes with the dimethylformamidinate and the dithioformate ligands have singlet ground states whose non‐covalently bonded NiNi distances are close to those in their experimentally known counterparts. Trigonal dinickel complexes are unknown, but are predicted to have quartet ground states with NiNi bonds of order 0.5. The model digonal complexes are predicted to have triplet ground states, but the predicted NiNi bond lengths are longer than those found in their experimentally known counterparts. This could owe to inadequate treatment of electron correlation by DFT in these short NiNi bonds with their multiconfigurational character. All the NiNi bond distances here are categorized into ranges according to the NiNi bond orders of 0, 0.5, 1, 1.5, and 2, no NiNi bonds of order higher than two being identified. The NiNi bonds of given order in these lantern‐type complexes are consistently shorter than the corresponding NiNi bonds in dinickel complexes having carbonyl ligands, attributable to the metalmetal bond lengthening effect of CO ligands.
Vanadium forms binuclear complexes with a variety of ligands often containing V≡V triple bonds. Many tetragonal divanadium paddlewheel complexes with bridging bidentate ligands have been experimentally characterized. This research exhaustively treats model tetragonal, trigonal, and digonal paddlewheel‐type divanadium complexes V2L
- NSF-PAR ID:
- 10288042
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemPhysChem
- Volume:
- 22
- Issue:
- 19
- ISSN:
- 1439-4235
- Page Range / eLocation ID:
- p. 2014-2024
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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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. -
Abstract With the aim of constructing hydrogen‐bonding networks in synthetic complexes, two new ligands derived from
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Abstract Binuclear alkyne manganese carbonyls of the type (RC≡CR')Mn2(CO)
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