A series of novel organic–inorganic hybrids based on α-[AlW12O40]5− polyoxoanions and transition-metal organoamine complexes

Abstract

A series of novel organic–inorganic assemblies, {Ag₃(2,2′-bipy)₂(4,4′-bipy)₂}{Ag(2,2′-bipy)₂}{Ag(2,2′-bipy)}[AlW₁₂O₄₀]·H₂O (1), [Ag(phen)₂]₃[Ag(phen)₃][AlW₁₂O₄₀]·H₅O₂ (2) and {Co(2,2′-bipy)₃}₃{Co(H₂O)(2,2′-bipy)₂[AlW₁₂O₄₀]}₂·H₂O (3) (2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine, phen = 1,10-phenanthroline) constructed from Keggin-type [AlW₁₂O₄₀]⁵⁻ polyoxoanion and transition-metal organoamine subunits, have been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis (TGA), electrochemical properties and single-crystal X-ray diffraction. A remarkable aspect of compound 1 is that there exists four types of coordination configurations for the five crystallographically independent Ag centers, and this phenomenon has never been observed in polyoxometalate (POM) chemistry. The trimeric {[Ag(phen)₂]₃}³⁺ cluster in compound 2 is firstly extended into an interesting one-dimensional wave-like array and then is further extended into a three-dimensional supramolecular network with the [AlW₁₂O₄₀]⁵⁻clusters residing in the interstices of this three-dimensional framework. The most striking structure feature of compound 3 is that three water molecules linearly arrange between the adjacent monosupporting {Co(H₂O)(2,2′-bipy)₂[AlW₁₂O₄₀]}³⁻ anions, leading to the formation of the three-dimensional supramolecular network by weak interactions.