New one- and two-dimensional heterometallic Cu/Cd halogeno or thiocyanato bridged coordination polymers synthesized directly from elemental copper and cadmium oxide in the presence of ethylenediamine

Three heterometallic Cu/Cd complexes [Cu(en)(2)CdBr4].dmso (1), [Cu(en)(2)CdI4].dmf (2) and [{Cu(en)(2)}(3)Cd(NCS)(6)](NCS)(2) (3) have been synthesized by means of an open-air reaction of unactivated copper powder, cadmium oxide, NH4X (X = Br, I, NCS) and ethylenediamine in non-aqueous solvents, like dmso, dmf and CH3OH. The selection of a counter-anion in the initial ammonium salt provides a facile approach to the controlled assembly of one- or two-dimensional extended networks. Crystallographic investigations reveal that 1 and 2 possess 1D structures via semi-coordination (Cu2+... X) and hydrogen bonds (NH2... O-Solv) forming chains with a zigzag arrangement of copper and cadmium atoms. In complex 3 the cadmium atom of each Cd(NCS)(6)(4-) anionic block forms bridges with Cu(II) ions via the sulfur atoms of thiocyanate groups to give 2D polymeric sheets, featuring two different ring sizes, one a 32-membered ring [Cu4Cd4(mu-SCN-S,N)(8)] and the other a 16-membered ring [Cu2Cd2(mu-SCN-S,N)4]. It is noteworthy, that 3 shows a quite rare Cd(NCS)(6)(4-) fragment with N-bonded thiocyanate groups.