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

The complex, bis-(N,N-diethyl-4-methyl-4-piperazine-1-carboxamide) tetra-kis(iso-thio-cyanato-κN)cobalt(II) (N,N-diethyl-4-methyl-4-piperazine-1-carboxamide = di-ethyl-carbamazine), (C(10)H(22)N(3)O)(2)[Co(NCS)(4)], 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, [K(2)Co(NCS)(4)]·3H(2)O, has a deep-blue coloration due to the tetra-hedral [Co(NCS)(4)](2-) 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(4)](2-). The structure is consistent with a previous proposal that a hydro-phobic ion pair formed between [Co(NCS)(4)](2-) and two protonated mol-ecules of cocaine is responsible for the blue hydro-phobic products formed by cocaine in the Scott test.