C₂H₅Hg⁺. Ethylmercury is a cation that forms organic mercury compounds such as ethylmercury chloride and ethylmercury urea. Thimerosal is also an ethylmercury salt: sodium ethylmercuric thiosalicylate. The term 'ethylmercury' is sometimes used as a generic term to describe ethylmercury compounds.