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Stabilization of a two-coordinate mononuclear cobalt(0) compound
Kartik Chandra Mondal1, Sudipta Roy, Susmita De
1Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, 37077 Göttingen (Germany).
Chemistry (Weinheim an Der Bergstrasse, Germany)
|July 23, 2014
Summary
Researchers synthesized a novel cobalt(0) compound stabilized by cyclic (alkyl) amino carbene ligands. This unique quasi-linear complex exhibits unusual electronic properties due to its bent metallaallene structure.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Inorganic Synthesis
Background:
- Cyclic (alkyl) amino carbene (cAAC) ligands are known for stabilizing metal complexes.
- Cobalt complexes in low oxidation states are of interest for their unique reactivity and bonding.
- The synthesis of metallaallene structures presents challenges in stabilizing unusual geometries.
Purpose of the Study:
- To synthesize and characterize a novel cobalt(0) complex featuring two Me2-cAAC ligands.
- To investigate the structural and electronic properties of the resulting bent 2-metallaallene.
- To explore the bonding nature within the cAAC-Co-cAAC framework.
Main Methods:
- Synthesis via reduction of a cobalt(I) precursor using KC8 in tetrahydrofuran (THF).
- Characterization using cyclic voltammetry, X-ray diffraction, and Electron Paramagnetic Resonance (EPR) spectroscopy.
- Analysis of bond lengths, bond angles, and electronic structure.
Main Results:
- Successful synthesis of the cobalt(0) compound, [(Me2-cAAC)2Co(0)].
- X-ray diffraction revealed a quasi-linear structure with Co-C bond lengths of ~1.87 Å and a C-Co-C angle of 170.12°.
- EPR spectroscopy showed broad resonance attributed to the unique structure, indicating rapid relaxation conditions and 2.5 nonbonding electron pairs on cobalt.
Conclusions:
- The reduction of the cobalt(I) precursor yields a stable cobalt(0) 2-metallaallene complex.
- The quasi-linear geometry and electronic structure are stabilized by the Me2-cAAC ligands.
- The Co-cAAC bonding can be described by a Dewar-Chatt-Duncanson model, highlighting significant nonbonding electron density on cobalt.
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