Diverse layered topology and magnetic subunits in cobalt cyclohexyldicarboxylate coordination polymers with 3-pyridylnicotinamide coligands

Abstract Three new divalent cobalt coordination polymers containing anionic cyclohexyldicarboxylate and neutral 3-pyridylnicotinamide (3-pna) tethering ligands have been prepared and structurally characterized via single-crystal X-ray diffraction. These phases show a diversity of layered topologies and differences in cobalt atom aggregation. [Co( cis -12chedc)(3-pna)(H 2 O)] n ( 1 , cis -12chedc = 4-cyclohexene- cis -1,2-dicarboxylate) shows a standard (4,4) grid topology with magnetically isolated cobalt atoms. [Co( cis -13cdc)(3-pna)] n ( 2 , cis -13cdc =  cis -cyclohexane-1,3-dicarboxylate) shows a 2D 3,5-connected net with a previously unreported (3.5 2 )(3 2 5 3 6 4 7) topology featuring “infinite” anti – syn bridged {Co(OCO)} n chain motifs pillared by 3-pna ligands. [Co( cis -14cdc)(3-pna)] n ( 3 , cis -14cdc =  cis -cyclohexane-1,4-dicarboxylate) shows a 2D 6-connected triangular net with (3,6) topology built from {Co 2 (OCO) 2 } dimeric units linked by cis -14cdc and 3-pna tethers. Magnetic susceptibility studies of compound 2 revealed a decrease in χ m T product upon cooling, ascribed to antiferromagnetic coupling along the {Co(OCO)} n chain motifs concomitant with Kramers doublet formation ( g  = 2.24(3), D  = 12.8(8) cm −1 , J  = –0.46(6) cm −1 ). For compound 3 , Kramers doublet formation was also observed, but with ferromagnetic superexchange within its {Co 2 (OCO) 2 } dimeric units ( g  = 2.27(1), D  = 24(1) cm −1 , J  = 0.35(2) cm −1 ). Thermal decomposition behavior of the three new phases is also discussed.