New heterometallic coordination polymers self-assembled from copper(II) nitrate and (diamine)Pt-II(pyridinecarboxylates)(2)

Abstract

One-dimensional (1-D), two-dimensional (2-D), and three-dimensional (3-D) coordination polymers were prepared by self-assembly of binary metal complex systems, copper(II) nitrate and (en)Pt-II(nic)(2) or (dmpda)Pt-II(isonic)(2) (en = ethylenediamine, dmpda = 2,2'-dimethyl-1,3-propanediamine, nic = nicotinate, and isonic = isonicotinate), in aqueous solutions. Equimolar reactions of copper(II) nitrate with (dmpda)Pt-II(isonic)(2) and (en)Pt-II(nic)(2) resulted in 1-D {[(dmpda)Pt(isonic)(2)Cu(OH2)(3)](NO3)(2)}(n) (1) and 2-D {[(en)Pt(nic)(2)Cu(OH2)](NO3)(2)}(n) (2), respectively, but the reaction of (en)Pt-II(nic)(2) with excess copper(II) nitrate gave 3-D {[((en)Pt(nic)(2))(3)Cu-5(OH)(2)(OH2)(6)](NO3)(8)}(n) (3). The local structure of crystal 1 has a mononuclear copper unit, 2 has a dinuclear copper unit with a Cu-Cu distance of 2.659(5) Angstrom, and 3 has a pentanuclear copper unit. The methyl groups of the dmpda ligand are located in the space between two isonicotinate ligands of 1, which is presumed to be an important factor to determine the final structure of the crystal formed by self-assembly. Magnetic behaviors of crystals 1-3 examined in the temperature range of 4-300 K appear to be governed by the local structures around the copper(II) ions and do not indicate any significant long-range magnetic exchange interactions along the polymeric chain.