Bis(,-diethyl-4-methyl-4-piperazine-1-carboxamide) tetra-kis-(iso-thio-cyanato-κ)-cobalt(II), a model compound for the blue color developed in the Scott test.

The complex, bis-(,-diethyl-4-methyl-4-piperazine-1-carboxamide) tetra-kis(iso-thio-cyanato-κ)cobalt(II) (,-diethyl-4-methyl-4-piperazine-1-carboxamide = di-ethyl-carbamazine), (CHNO)[Co(NCS)], is presented. This com-plex is a blue precipitate, insoluble in water but soluble in organic solvents, that is formed from the reaction of diethylcarbamazine citrate, a protonated tertiary amine, with cobalt(II) and thio-cyanate. This reaction, in the form of the Scott test, is a common presumptive test for cocaine hydro-chloride. The known cobalt compound, [KCo(NCS)]·3HO, has a deep-blue coloration due to the tetra-hedral [Co(NCS)] that is also present in the ion pair with bulky amines, and is similar to the color of other tetra-hedral cobalt(II) complex ions, such as [CoCl]. The structure is consistent with a previous proposal that a hydro-phobic ion pair formed between [Co(NCS)] and two protonated mol-ecules of cocaine is responsible for the blue hydro-phobic products formed by cocaine in the Scott test.