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Self‐assembly of cobalt(II) coordination polymers with differently halosubstituted nicotinate ligands and 4,4’‐bipyridine – the effect of the halosubstituent positions on polymer types

Two structurally different 1D cobalt(II) coordination polymers with 4, 4’‐bipyridine (4, 4’‐bpy) and 2‐chloronicotinate (2‐Cl‐nic) or 5‐ bromonicotinate (5‐Br‐nic), namely {; ; ; ; [Co(2‐ Cl‐ nic)2(4, 4’‐bpy)(H2O)2] ⋅ 4H2O}; ; ; ; n (1) and {; ; ; ; [Co(4, 4’‐bpy)(H2O)4] [Co(5‐Br‐ nic)4(H2O)2] ⋅ 4, 4’‐bpy ⋅ 2H2O}; ; ; ; n (2), were prepared under the same experimental conditions. The cobalt(II) ions in 1 are bridged by 4, 4’‐bipyridine ligands into a 1D polymeric chain, each cobalt(II) ion being coordinated with two O‐ monodentate 2‐ chloronicotinate ligands and two water molecules as well, while 2 consists of a complex cation {; ; ; ; [Co(4, 4’‐bpy)(H2O)4]2+}; ; ; ; n, in which cobalt(II) ions are bridged by 4, 4’‐ bipyridine ligands into a 1D polymeric chain, and a complex anion [Co(5‐Br‐ nic)4(H2O)2]2−, in which cobalt(II) ion is coordinated with four 5‐bromonicotinate ligands (two of them being O‐ monodentate and the other two are N‐ monodentate) and two water molecules. DFT calculations revealed a correlation between the halosubstituent (chlorine or bromine) positions in the employed nicotinate ligands and the cobalt(II) coordination environments in the obtained coordination polymers, being responsible for their different structural types.

cobalt ; halosubstituted nicotinate ; coordination polymer ; crystal structure ; DFT calculations

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