Two 1,3-dialkyne-functionalized imidazolium chlorides, 1,3-dipropynylimidazolium chloride and 1,3-dipentynylimidazolium chloride, have been prepared from the direct reaction between the appropriate chloroalkyne and (trimethylsilyl)imidazole. Replacement of the chloride counterion with BF4- or BPh4- gave four further imidazolium salts, three of which melt below 100 degreesC and one of which is a liquid at room temperature. Reactions of the BF4- and BPh4- salts with Co-2(CO)(8) afforded complexes in which both of the alkyne functionalities coordinated to a CO2(CO)(6) unit. One of these organometallic derivatives, viz. 1,3-dipentynylimidazolium bis(hexacarbonyldicobalt) tetrafluoroborate, can be classified as an ionic liquid on the basis of its melting point. The solid-state structures of three of these new salts have been elucidated by single-crystal X-ray diffraction, revealing extensive networks of C(...)H(...)pi and pi(...)pi interactions. Attempts to prepare carbene derivatives from the functionalized imidazolium salts have also been made.
Paul Joseph Dyson, Sarah Alexandra Pais Pereira
Moreno Lelli, Pierrick Berruyer, David Benjamin Roger Antoine Gajan, Zhuoran Wang