Syntheses, crystal structures and supramolecular topologies of nickel(II)–s/p/d10/NH4+ complexes derived from a compartmental ligand

Abstract

The syntheses, characterization and crystal structures of ten complexes of composition [{Ni^IILLi^I(H₂O)₂}{Ni^IIL}₂](ClO₄) (1), [Ni^IILNa^I(ClO₄)(CH₃OH)] (2), [(Ni^IIL)₂Na^I](BPh₄)·CH₃COCH₃ (3), [(Ni^IIL)₂Rb^I](BPh₄)·CH₃COCH₃ (4), [(Ni^IIL)₂Cs^I](ClO₄)·CH₃CN (5), [{Ni^IILMg^II(H₂O)₃}{Ni^IIL}₂](ClO₄)₂ (6), [Ni^IILCa^II(NO₃)₂(H₂O)]·1.5H₂O (7), [Ni^IILCd^II(NO₃)₂]·CH₃CN (8), [Ni^IILPb^II(NO₃)₂] (9) and [(Ni^IIL)₂(NH₄)](PF₆) (10) are reported, where H₂L = N,N′-ethylenebis(3-ethoxysalicylaldimine). The crystal systems and space groups are: triclinic Pī for 1, 4, 5 and 8, monoclinic P2₁/c for 2, 3, 7 and 9, monoclinic C2/c for 6 and monoclinic P2₁/n for 10. In 1–10, the salen type N₂O₂ compartment of [L]²⁻ is occupied by a Ni^II ion, while the larger and open O(phenoxo)₂O(ethoxy)₂ compartment interacts with Li^I in 1, Na^I in 2 and 3, Rb^I in 4, Cs^I in 5, Mg^II in 6, Ca^II in 7, Cd^II in 8, Pb^II in 9 and NH₄⁺ in 10. Compounds 1 and 6 are [2 × 1 + 1 × 2] tetrametallic cocrystals of one diphenoxo-bridged dinuclear Ni^IILi^I (for 1) and Ni^IIMg^II (for 6) unit and two mononuclear [Ni^IIL] moieties. Compounds 2, 7, 8 and 9 are diphenoxo-bridged dinuclear Ni^IINa^I, Ni^IICa^II and Ni^IICd^II and Ni^IIPb^II systems, respectively. On the other hand, compounds 3, 4 and 5 are trinuclear Ni^II₂Na^I, Ni^II₂Rb^I and Ni^II₂Cs^I systems, respectively, in which each of the two adjacent pairs of metal ions is diphenoxo-bridged. The rubidium(I) and cesium(I) analogues are also double-decker sandwich systems. The ammonium ion in [(Ni^IIL)₂(NH₄)](PF₆) (10) is sandwiched in between two [Ni^IIL] moieties due to hydrogen bonds between ammonium hydrogen atoms and O₄ compartments. Weak interaction assisted following self-assemblies are observed: dimeric in 1 and one-dimensional in 10 due to Ni⋯Ni weak interaction; one-dimensional in 2 due to C–H⋯π and O–H⋯O hydrogen bonds; nice cyclic topology in 5 due to Ni⋯Ni interaction and C–H⋯O hydrogen bonds; one-dimensional in 6 due to Ni⋯Ni interaction and C–H⋯O hydrogen bond; one-dimensional in 8 due to π···π stacking.