Supramolecular structural influences from remote functionality in coordination complexes of 4-picolylamine ligands

Abstract

A series of nine cobalt(II), copper(II) and silver(I) coordination complexes of structurally similar picolylamine ligands, N-(4-picolyl)piperidine (L1) and N-(4-picolyl)morpholine (L2), have been prepared and analyzed. These consist of a dinuclear copper(II) complex [Cu2(OAc)4(L1)2] (1), tetranuclear copper(II) complexes [Cu4OCl6(L1)4]·MeCN·H2O (2) and [Cu4OCl7(L2)2 (L2H)]·2MeCN·9H2O (3), trichlorocobaltate complexes [CoCl3 (L1H)]·MeCN (4) and [CoCl3(L2H)] (5), silver coordination polymers poly-[AgL1]SbF6·0.5THF) (6), poly-[Ag(L2)]SbF6·0.5THF (7) and poly-[Ag(L1)(CO2CF3)] (9) and discrete dinuclear silver complex [Ag2(L2)2(THF)4](SbF6)2 (8). While the coordination and classical N–H···X hydrogen bonding in these species is related and largely independent of backbone functionality, differences in ligand composition dictate the d weak interactions and the supramolecular structure. In 1, 2, 4, 6 and 9 piperidine acts as a weak hydrogen bond donor, with C–H···Cl/O/F contacts mostly observed from the methylene groups adjacent to the amine. In the morpholine species 3, 5, 7 and 8 the tendency for morpholine to associate via reciprocated C–H···O interactions overrides the other crystal packing tendencies, changing both the local and extended structures. By studying both strong and weak packing interactions, this study presents a test case for the design of discrete and polymeric coordination compounds with finely tuned modes of intermolecular interaction.