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 24-(4-methoxyphenyl)-12,22:26,32-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 CHCl3 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}·2.2CHCl3] 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.