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

Abstract

The work in this report deals with seven compounds of composition {[CuII(dmpn)2]3[FeIII(CN)6]2·6H2O}n (1), {[CuII(dmpn)2]3[CoIII(CN)6]2·6H2O}n (2), {[CuII(dmpn)2]3[CrIII(CN)6]2·4H2O}n (3), {[CuII(dmpn)][NiII(CN)4]·H2O}n (4), [{CuII(dmpn)2Cl}{CuII(dmpn)2(H2O)}][AgI(CN)2]Cl2 (5), [(CuII(dmpn)2(dicyanamide)2] (6) and [(NiII(dmpn)2(dicyanamide)2] (7), where dmpn=2,2-dimethyl-1,3-diaminopropane. Syntheses, characterization and crystal structures of 1–7 along with variable-temperature (2–300K) 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 CuII and CrIII in 3. In addition, spin–orbit coupling of low-spin FeIII or weak antiferromagnetic interaction along with intermolecular antiferromagnetic interactions which exist between CuII and FeIII are present in 1.