Investigation of a mercury(II) carbene complex: bis(1,3-dimethylimidazol-2-ylidene) mercury chloride

The reaction of 1,3-dimethylimidazolium chloride with Hg(O₂CCH₃)₂ afforded a bis(carbene)mercury(II) complex (2), which is characterized by multinuclear NMR spectroscopy (¹H, ¹³C, ¹⁵N, and ¹⁹⁹Hg) and by single-crystal X-ray analysis. As a consequence of chloride-ion interaction with the mercury center, the C₂-Hg-C₂ angle in 2 is reduced to 161.4 (3)° compared to its near-linear value in complex 4 that contains perchlorate counterions. The C₂ resonance in the mercury complex 2 moves upfield by 36.96 ppm relative to the parent carbene (2), with a large ¹J_HgC = 2741.18 Hz. © 1996 John Wiley & Sons, Inc.