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

Abstract

Abstract Three heterometallic Cu/Cd complexes [Cu(en)2CdBr4]·dmso (1), [Cu(en)2CdI4]·dmf (2) and [{Cu(en)2}3Cd(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 . . . OSolv) forming chains with a zigzag arrangement of copper and cadmium atoms. In complex 3 the cadmium atom of each Cd(NCS)64− 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(μ−SCN−S,N)8] and the other a 16- membered ring [Cu2Cd2(μ−SCN−S,N)4]. It is noteworthy, that 3 shows a quite rare Cd(NCS)64− fragment with N-bonded thiocyanate groups.