Abstract
A comparative investigation of the coordination assemblies formed between Co(NCS)&sub2; and two monotopic 4,2':6',4''-terpyridine (4,2':6',4"-tpy) ligands or two related ditopic ligands is reported. Crystals were grown by layering MeOH solutions of Co(NCS)&sub2; over a CHCl&sub3; or 1,2-C₆H&sub4;Cl&sub2; solution of the respective ligand at room temperature. With 4'-(2-methylpyrimidin-5-yl)-4,2':6',4"-terpyridine (6), the 1D-coordination polymer {[Co&sub2;(NCS)&sub4;(MeOH)&sub4;(6)&sub2;]∙2MeOH∙8H&sub2;O}n assembles with 6 coordinating only through the outer N-donors of the 4,2':6',4"-tpy unit; coordination by the MeOH solvent blocks two cobalt coordination sites preventing propagation in a higher-dimensional network. A combination of Co(NCS)&sub2; and 1-(4,2':6',4"-terpyridin-4'-yl)ferrocene (7) leads to {[Co(NCS)&sub2;(7)&sub2;]∙4CHCl&sub3;}n which contains a (4,4) net; the 2D-sheets associate through π-stacking interactions between ferrocenyl and pyridyl units. A 3D-framework is achieved through use of the ditopic ligand 1,4-bis(npropoxy)-2,5-bis(4,2':6',4"-terpyridin-4'-yl)benzene (8) which acts as a 4-connecting node in {[Co(NCS)&sub2;(8)&sub2;].2C₆H&sub4;Cl&sub2;}n; the combination of metal and ligand planar 4-connecting nodes results in a {6&sup5;.8} cds net. For a comparison with the coordinating abilities of the previously reported 1,4-bis(noctoxy)-2,5-bis(4,2':6',4"-terpyridin-4'-yl)benzene (3), a more flexible analogue 9 was prepared. {[Co(NCS)&sub2;(9)]∙2CHCl&sub3;}n contains a (4,4) net defined by both metal and ligand planar 4-connecting nodes. The noctoxy tails of 9 protrude from each side of the (4,4) net and thread through adjacent sheets; the arene-attached noctoxy chains associate through a combination of van der Waals and C-H...π interactions.