Coordination polymers with divergent 4′-tert-butyl-4,2′:6′,4′′-terpyridine linkers: from aryl-aryl to ball-and-socket packing

Abstract

The synthesis and structural characterization of 4′-tert-butyl-4,2′:6′,4′′-terpyridine (1) are presented, along with the first coordination polymers containing a 4,2′:6′,4′′-tpy ligand in which a non-aryl substituent is attached directly to the 4′-position. In [{ZnI₂(1)·1,2-Cl₂C₆H₄}_n], face-to-face π-stacking between 1,2-Cl₂C₆H₄ solvent molecules and 4,2′:6′,4′′-tpy domains controls the assembly of the {ZnI₂(1)}_n chains and this outweighs the steric effects of the ^tBu groups. The one-dimensional chains observed in [{Zn₂(μ-OAc)₄(1)}_n] and their packing in the solid state are closely related to those in [{Zn₂(μ-OAc)₄L}_n] where L is 4′-phenyl-, 4′-(4-bromophenyl)- or 4′-(4-methylthiophenyl)-4,2′:6′,4′′-terpyridine; the ^tBu group is accommodated in a similar sized cavity as each of the aryl substituents and in each polymer, the most important packing interactions are those between the 4,2′:6′,4′′-tpy units. Reaction between 1 and Co(SCN)₂ results in the assembly of two-dimensional sheets containing octahedral trans-CoS₂N₄ nodes; tert-butyl groups protrude from both surfaces of the sheets, and a ‘ball-and-socket’ assembly supported by CH_butyl⋯N_pyridine hydrogen bonds locks the sheets together.