Novel pyridinium based cobalt carbonyl ionic liquids: synthesis, full characterization, crystal structure and application in catalysis

Through an optimized synthetic strategy, a series of novel alkylpyridinium cobalt tetracarbonyl salts, [C1Py][Co(CO)(4)] (2a), [C4Py][Co(CO)(4)] (2b) and [C16Py][ Co(CO)(4)] (2c) (CnPy = N-CnH2n+ 1-pyridinium), were successfully prepared in good yields, using a water-organic biphasic system. All the three compounds melt well below 100 degrees C and could be classified as ionic liquids. The compounds were fully characterized using IR, UV- Vis, H-1 NMR, C-13 NMR, ESI-MS and elemental analysis, and 2c was structurally characterized by X-ray single crystal analysis. Compound 2b has been found to be an efficient and reusable catalyst for the alkoxycarbonylation of propylene oxide without the aid of a base additive.