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 synthesis 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 unexpected undulating molecular parquet pattern, while compound 2 has an infinite one-dimensional pattern with interpenetrating molecular ladders. Both isomers 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 distorted T-shaped building block, on which the infinite frameworks of both compounds are based.