Fabrication of metal–organic hybrid architectures using bridging diphenyl phosphate: Syntheses, characterization, magnetic properties and the effect of weak interactions on their crystal packing

Abstract

Ten different metal-organic hybrids of divalent metal ions have been synthesized using the diphenyl phosphate ligand and three different N,N donor spacers. All the complexes have been characterized by single crystal X-ray crystallography and other physico-chemical methods. For six complexes, the diphenyl phosphate (dpp) ligand acts as a bridge between the metal ions, whereas in four complexes dpp acts as a monodentate ligand. All nine complexes (1-9) show two dimensional coordination structures created by the N,N donor spacers, and, the remaining one (10) has a one dimensional ribbon-like structure. Here the aromatic rings present in the compounds viz. phenyl rings of dpp and the pyridyl rings of N,N donor spacers, have a key role to extend the dimensionality in their solid-state structures. In each instance, the aromatic rings of dpp and N,N donor spacers are nicely involved in the supramolecular structure generation by the help of π-π interactions. In all the cases, the role of weak interactions on the crystal packing and their effect in the generation of different supramolecular architectures has been thoroughly investigated. Variable temperature magnetic measurements of three relevant complexes have been carried out. Compounds 1 and 3 clearly indicate the existence of a weak antiferromagnetic interaction between the metal ions through the bridging dpp ligand. In 5, where dpp acts as a monodentate ligand; the metal ion may be considered as an isolated monomer.