A novel imidazole-type carbene of platinum(II), cis-(C2H4)(1-ethyl-3-methyl
imidazol-2-ylidene)PtCl2 (1), has been obtained by reacting a mixture of Pt
Cl2 and PtCl4 with ethylene (50 atm) in the basic [EMIM]CI/AlCl3 (1.3:1) io
nic liquid at 200 degrees C (where [EMIM](+) = 1-ethyl-3-methyl-imidazolium
) and characterised by X-ray analysis.