| Abstract |
Three new Cu/Cd, mixed-anion solid-state coordination polymers [Cu(en)(2)Cd(mu-CI)(mu-O2CMe)CI(O2CMe)](n) (1), [Cu(en)(2)-CdI (1.64)(O2CMe)(2.36)](n) (2) and [Cu-2(en)(4)Cd-2(NCS)(6)(O2CMe)(2)](n) (3) have been prepared using unactivated copper powder, cadmium acetate, NH4X (X = CI, I, NCS) and ethylenediamine in non-aqueous solvents, namely dmso, dmf and CH3OH, in the open air. Depending on the nature of the selected counter-anion in the initial ammonium salt, a facile approach to the controlled assembly of 1D or 2D extended networks has been offered. X-ray studies show that 1 and 2 possess 1D helical chain crystal structures, constituting cationic Cu(en)(2)(2+) and mixed-ligand anionic Cd(mu-CI)(mu-O2CMe)CI(O2CMe)(2-), Cd(mu-O2CMe)(2)I(O2CMe)(2-) or Cd(mu-I)-(mu-O2CMe)I(O2CMe)(2-) building blocks, conjoining together through the oxygen atoms of chelating bidentate and simultaneously bridging unidentate acetate ligands and also by a bridging chlorine atom (for 1) and by a bridging iodine or oxygen atom of a weakly bidentate acetate group (for 2). In both complexes, distinct hydrogen bonds are present and serve to increase the dimensionality of the compound from one to two. The 2D polymeric sheet of complex 3 consists of a ID mixed-anion polymer -NCS-Cd(NCS)(2)(O2CMe)-SCN-Cd(NCS)(2)(O2CMe)-NCS- and Cu(en)(2) units. Each of two crystallographically independent cadmium atoms has six coordination, consisting of CdN4O2 or CdS2N2O2 distorted octahedral geometries. The copper atom of Cu(en)2 also exhibits a distorted octahedral arrangement. Apical bonds between the Cu(II) and S atoms from terminal NCS-groups [3.1113(12) and 3.1467(14) angstrom] link the anionic chains forming a 2D network. Variable-temperature magnetic susceptibility measurements of 1-3 show weak antiferromagnetic coupling between the copper centres. (c) 2005 Elsevier Ltd. All rights reserved. |
