Competition in Coordination Assemblies: 1D-Coordination Polymer or 2D-Nets Based on Co(NCS)(2) and 4′-(4-methoxyphenyl)-3,2′:6′,3″-terpyridine

The synthesis and characterization of 4′-(4-methoxyphenyl)-3,2′:6′,3″-terpyridine (2) (IUPAC PIN 2(4)-(4-methoxyphenyl)-1(2),2(2):2(6),3(2)-terpyridine) are described, and its coordination behaviour with cobalt(II) thiocyanate has been investigated. In a series of experiments, crystals were grown at room temperature by layering a MeOH solution of Co(NCS)(2) over a CHCl(3) solution of 2 using 1:1, 1:2 or 2:1 molar ratios of metal salt-to-ligand. Crystals harvested within 2–3 weeks proved to be the 1D-coordination polymer [Co(2)(NCS)(2)(MeOH)(2)](n) and powder X-ray diffraction (PXRD) confirmed that the crystals selected for single-crystal X-ray diffraction were representative of the bulk samples. Longer crystallization times with a Co(NCS)(2) to 2 molar ratio of 1:1 yielded crystals of [Co(2)(NCS)(2)(MeOH)(2)](n) (1D-chain) and the pseudopolymorphs [{Co(2)(2)(NCS)(2)}·3MeOH](n) and [{Co(2)(2)(NCS)(2)}·2.2CHCl(3)](n) ((4,4)-nets), each type of crystal originating from a different zone in the crystallization tube. PXRD for this last experiment confirmed that the dominant product in the bulk sample was the 1D-coordination polymer.