Unexpected formation of novel organometallic hetero-cation crystals with a rare coordination mode

Abstract

The imitative synthesis of the ionic liquid [bmim][Co(CO)₄], carried out in organic solvents instead of water, produced an unexpected liquid complex with partial crystallization. The resulting solid was confirmed to be the novel hetero-cation salt, [bmim]K[Co(CO)₄]₂ (1) and a crystallographic investigation revealed an extremely unusual (CO)₇–K coordination mode. When the organic cation was replaced by [C₄Py]⁺, similar crystallization was also obtained, forming [C₄Py]K[Co(CO)₄]₂ (2), which has an analogous structure. Both of these cases indicate an interesting influence that these organic cations have on the crystallization of organometallic structures that yields new structural examples.