Synthesis and Reactivity of an Isolable Cobalt(I) Complex Containing a β-Diketiminate-Based Acyclic Tetradentate Ligand

A model for cobalamin was synthesized using a new monoanionic tetradentate nitrogen donor ligand; 2-(4-tolyl)-1,3-bis(2-isopropylpyridyl)­propenediimine (Tol-BDI(2‑pp)2H) (1), which utilizes isopropylpyridines as pendant arms on a β-diketiminate (BDI) backbone. During the synthesis of 1, the rearran...

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Bibliographic Details
Published in:Inorganic chemistry 2012-02, Vol.51 (4), p.2079-2085
Main Authors: Marlier, Elodie E, Ulrich, Bridget A, McNeill, Kristopher
Format: Article
Language:English
Subjects:
Cobalt - chemistry
Coordination Complexes - chemical synthesis
Coordination Complexes - chemistry
Crystallography, X-Ray
Electrochemical Techniques
Imines - chemical synthesis
Imines - chemistry
Ligands
Models, Molecular
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Summary:A model for cobalamin was synthesized using a new monoanionic tetradentate nitrogen donor ligand; 2-(4-tolyl)-1,3-bis(2-isopropylpyridyl)­propenediimine (Tol-BDI(2‑pp)2H) (1), which utilizes isopropylpyridines as pendant arms on a β-diketiminate (BDI) backbone. During the synthesis of 1, the rearrangement product, Tol-BDI(2‑pp)(4‑pp)H (2) was observed. Metalation of 1 with zinc iodide and cobalt chloride yielded the corresponding Tol-BDI(2‑pp)2ZnI (3) and Tol-BDI(2‑pp)2CoCl (4) complexes. The redox properties of 4 in comparison to cobalamin were examined through electrochemical studies. Electrochemical and bulk reduction of complex 4 gave a diamagnetic cobalt(I) complex, Tol-BDI(2‑pp)2Co (5). Reactivity of 5 toward C-X bonds was investigated using methyl iodide and 1-iodo-2-(trimethylsilyl)acetylene, yielding Tol-BDI(2‑pp)2Co(CH3)I and Tol-BDI(2‑pp)2Co(C2Si(CH3)3)I respectively. Synthesis and characterization details for these complexes, including the crystal structure of 3, are reported.
ISSN:0020-1669
1520-510X
DOI:10.1021/ic201780c