Bis(N,N-diethyl-4-methyl-4-piperazine-1-carboxamide) tetra­kis­(iso­thio­cyanato-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) tetra­kis(iso­thio­cyanato-κN)cobalt(II) (N,N-diethyl-4-methyl-4-piperazine-1-carboxamide = di­ethyl­carbamazine), (C(10)H(22)N(3)O)(2)[Co(NCS)(4)], is presented. This com­plex 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 thio­cyanate. This reaction, in the form of the Scott test, is a common presumptive test for cocaine hydro­chloride. The known cobalt compound, [K(2)Co(NCS)(4)]·3H(2)O, has a deep-blue coloration due to the tetra­hedral [Co(NCS)(4)](2−) that is also present in the ion pair with bulky amines, and is similar to the color of other tetra­hedral cobalt(II) complex ions, such as [CoCl(4)](2−). The structure is consistent with a previous proposal that a hydro­phobic ion pair formed between [Co(NCS)(4)](2−) and two protonated mol­ecules of cocaine is responsible for the blue hydro­phobic products formed by cocaine in the Scott test.