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Low-oxidation state cobalt-magnesium complexes: ion-pairing and reactivity
John A Kelly1, Johannes Gramüller2, Ruth M Gschwind2
1University of Regensburg, Institute of Inorganic Chemistry, 93040 Regensburg, Germany. robert.wolf@ur.de.
Dalton Transactions (Cambridge, England : 2003)
|September 20, 2021
Summary
New magnesium cobaltate complexes were synthesized and their reactivity explored. Ion-pairing effects influenced the formation of unique 1,3-diphosphacyclobutadiene complexes and phosphorus-rich compounds.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Main Group Chemistry
Background:
- Magnesium cobaltates represent an emerging class of bimetallic compounds with potential applications in catalysis and materials science.
- Understanding the influence of solvent and ion-pairing on the reactivity of these complexes is crucial for designing new synthetic routes and functional materials.
Purpose of the Study:
- To synthesize novel magnesium cobaltate complexes with varying N-heterocyclic carbene (nacnac) ligands.
- To investigate the impact of ion-pairing (contact vs. solvent-separated) on the reactivity of these complexes, particularly in reactions with phosphaalkynes.
- To explore the potential of these complexes as precursors for novel organometallic compounds, including phosphorus-rich structures.
Main Methods:
- Synthesis of magnesium cobaltates (1-3) via reaction of magnesium precursors with potassium cobaltate complexes.
- Spectroscopic characterization (NMR, X-ray crystallography) of synthesized compounds.
- Reactivity studies involving reactions with tert-butylphosphaalkyne, white phosphorus (P4), and nickel complexes.
Main Results:
- Successfully synthesized magnesium cobaltates (1-3) featuring different aryl nacnac ligands.
- Demonstrated that ion-pairing in toluene (contact ion-pairs) versus THF (solvent-separated ion-pairs) dictates the outcome of reactions with tert-butylphosphaalkyne, leading to distinct 1,3-diphosphacyclobutadiene complexes (4 and 5).
- Synthesized a phosphorus-rich sandwich compound (6) by substituting the COD ligand in complex 4 with white phosphorus.
- Prepared a heterobimetallic complex (7) through reaction of complex 4 with a nickel precursor.
Conclusions:
- The nature of ion-pairing in magnesium cobaltates significantly influences their reactivity and the resulting product distributions.
- Magnesium cobaltate complexes serve as versatile precursors for the synthesis of diverse organometallic compounds, including novel diphosphacyclobutadienes and phosphorus-rich materials.
- This study expands the scope of magnesium cobaltate chemistry, highlighting their utility in constructing complex inorganic and organometallic architectures.
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