New crystalline frameworks formed from 1,2-bis(4-pyridyl)ethyne and Co(NO3)(2): Interpenetrating molecular ladders and an unexpected molecular parquet pattern from T-shaped building blocks

Two isomeric members of an organic/inorganic network family, both with the formula Co(NO3)(2)(C12N2H8)(1.5) . MeOH, have been obtained in a one-pot sy nthesis by the reaction of 1,2-bis(4-pyridyl)ethyne with cobalt(II) nitrate hexahydrate in a MeOH/MeCN solvent mixture. Compound 1 (shown) has an unex pected undulating molecular parquet pattern, while compound 2 has an infini te one-dimensional pattern with interpenetrating molecular ladders. Both is omers feature a heptacoordinate cobalt atom, surrounded by three 1,2-bis(4- pyridyl)ethyne ligands and two bidentate nitrate ligands. The three 1,2-bis (4-pyridyl)ethyne ligands around the cobalt atom define a slightly distorte d T-shaped building block, on which the infinite frameworks of both compoun ds are based.