Discrete systems and two-dimensional coordination polymers containing potentially multidentate and bridging inorganic anions: Observation of a new type of two-dimensional topology

The work in this report deals with seven compounds of composition {[Cu-II(dmpn)(2)](3)[Fe-III(CN)(6)](2).6H(2)O)(n) (1), {[Cu-II(dmpn)(2)](3)[Co-III(CN)(6)](2)center dot 6H(2)O). (2), {[Cu-II(dmPn)(2)](3)[Cr-III(CN)(6)]2 center dot 4H(2)O) (3), {[Cu-II(dmpn)][Ni-II (CN)(4)]center dot H2O)(n) (4), {[Cu-II(dmpn)(2)Cl}{Cu-II(dmpn)(2)(H2O)}][Ag-1(CN)(2)]Cl-2 (5), [(Cu-II(dmpn)(2)(dicyanamide)(2)] (6) and [(Ni-II(dmpn)(2)(dicyanamide)(2)] (7), where dmpn = 2,2-dimethy1-1,3-diaminopropane. Syntheses, characterization and crystal structures of 1-7 along with variable-temperature (2-300 K) magnetic properties of 1 and 3 are described. Compounds 1-4 are cyanide-bridged two-dimensional coordination polymers. Twelve metal-membered ring is formed in 1-3, while both four and eight metal-membered rings are formed in 4. On the other hand, dicyanoargentate(I) in 5 is noncoordinated and dicyanamide in 6 and 7 behaves as monodentate terminal ligand. The coordination polymers in 1-4 and the discrete systems in 5-7 are self-assembled by hydrogen bonding interactions to generate overall three-dimensional supramolecular topologies. A novel structural aspect, two-dimensional network containing both four and eight metal-membered rings, has been observed in the copper(II)-tetracyanonickelate(II) compound 4. Magnetic studies reveal ferromagnetic interaction between Cu-II and Cr-III in 3. In addition, spin-orbit coupling of low-spin Fe-III or weak antiferromagnetic interaction along with intermolecular antiferromagnetic interactions which exist between Cu-II and Fe-III are present in 1. (C)2014 Elsevier Ltd. All rights reserved.