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A simple route to single-scorpionate nickel(II) complexes with minimum steric requirements
Patrick J Desrochers1, Adam L Corken, Richard M Tarkka
1Department of Chemistry, University of Central Arkansas, Conway, Arkansas 72035, USA. patrickd@uca.edu
Inorganic Chemistry
|March 26, 2009
Summary
Researchers developed new methods to synthesize single-scorpionate nickel(II) complexes, overcoming steric limitations. These kinetic products are stable solids but convert to thermodynamic products in solution, with potential applications in catalysis.
Area of Science:
- Coordination Chemistry
- Organometallic Chemistry
- Materials Science
Background:
- Single-scorpionate nickel(II) complexes (e.g., Tp(R)NiX) are kinetic products requiring steric hindrance for synthesis.
- Common scorpionate ligands like Tp* and Tpm readily form thermodynamically favored bis-ligand complexes.
Purpose of the Study:
- To report novel synthetic routes for single-ligand nickel(II) scorpionate complexes.
- To investigate the stability and reactivity of these kinetic products.
- To explore the potential of supported scorpionates in catalysis.
Main Methods:
- Synthesis of TpmNiX(2)(OH(2))(n) via a new route using tetrahalonickelate(II) ions in nitromethane.
- Preparation of Tpm*NiCl(2)(OH(2))(n) using an established alternative method.
- Covalent attachment of HOCH(2)Tpm to polystyrene beads for supported nickel(II) complex formation.
Main Results:
- Successfully synthesized TpmNiX(2)(OH(2))(n) and Tpm*NiCl(2)(OH(2))(n) complexes.
- Demonstrated that TpmNiX(2)(OH(2))(n) are stable solids but convert to (Tpm)(2)Ni(2+) in solution.
- Showed that supported Tpm-nickel(II) complexes exhibit comparable electronic spectra to homogeneous counterparts.
Conclusions:
- A new nitromethane/NiX(4)(2-) method provides access to monoscorpionates of first-row transition metals.
- Covalently supported scorpionates offer a promising avenue for heterogeneous catalysis and metal-protein interaction studies.
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