N-Butylmercuric chloride
n-Butylmercuric chloride is an organic mercury salt that is used as a catalyst and a precursor to other oganomercuric compounds. Preparation 
n-Butylmercuric chloride is made by reacting n-butylmagnesium bromide with mercury chloride. It can also be prepared by reacting 1-butene with mercury acetate. References 

Mercury(II) compounds
Organomercury compounds