Cation-controled formation of N,N'-dialkylimidazolium cadmium-thiocyanate complexes:: synthesis and structural characterization

Three new N,N'-dialkylimidazolium salts of cadmium-thiocyanate, [EtMeIm](2)[Cd-2(SCN)(6)] (2), [C6H4(CH(2)ImMe)(2)][Cd(SCN)(4)] (3), [C6Me3(CH(2)ImMe)(3)][CdBr3(SCN)](NO3) (4) have been prepared, and their crystal structures have been determined by X-ray diffraction. Crystal data: 2, monoclinic, C2/c, a = 18.349(4) Angstrom, b = 7.8667(18) Angstrom, c = 21.399(5) Angstrom, beta = 110.346(4)degrees, V = 2896.1 (11) Angstrom(3), Z = 4, and R1 = 0.0561; 3, monoclinic, C2/c, a = 20.347(7) Angstrom, b = 14.029(5) Angstrom, c = 9.380(3) Angstrom, beta = 112.034(6)degrees, V = 2482.1(15) Angstrom(3), Z = 4, and R1 = 0.0397; 4, hexagonal, P6(3), a = b = 10.7634(8) Angstrom, c = 16.0315(17) Angstrom, V = 1608.4(2) Angstrom(3), Z = 2, and R1 = 0.0569. Compound 2 consists of triply bridged infinite one-dimensional cadmium-thiocyanate chains, and two independent cadmium atoms are octahedrally coordinated in 2N4S and 4N2S geometry, respectively. In 3, the cadmium atom is octahedrally coordinated with two cis N-bonded monodentate NCS- ligands and four bridging SCN- in a S trans to S, and N trans to N coordination fashion, and thus form doubly bridged infinite one-dimensional chains. Whereas 4 is mononuclear, consisting of a discrete [C6Me3(CH(2)ImMe)(3)](3+) cation, a nitrate, and [CdBr3(SCN)](-) ion, and each cadmium(II) ion is coordinated to three bromide and one nitrogen atom of SCN- ion. The structures of these compounds are dictated by the imidazolium cations. (C) 2002 Elsevier Science (USA). All rights reserved.