Self-assembled 3D heterometallic Cu(II)/Fe(II) coordination polymers with octahedral net skeletons: structural features, molecular magnetism, thermal and oxidation catalytic properties.

The new three-dimensional (3D) heterometallic Cu(II)/Fe(II) coordination polymers [Cu(6)(H(2)tea)(6)Fe(CN)(6)](n)(NO(3))(2n)·6nH(2)O (1) and [Cu(6)(Hmdea)(6)Fe(CN)(6)](n)(NO(3))(2n)·7nH(2)O (2) have been easily generated by aqueous-medium self-assembly reactions of copper(II) nitrate with triethanolamine or N-methyldiethanolamine (H(3)tea or H(2)mdea, respectively), in the presence of potassium ferricyanide and sodium hydroxide. They have been isolated as air-stable crystalline solids and fully characterized including by single-crystal X-ray diffraction analyses. The latter reveal the formation of 3D metal-organic frameworks that are constructed from the [Cu(2)(µ-H(2)tea)(2)](2+) or [Cu(2)(µ-Hmdea)(2)](2+) nodes and the octahedral [Fe(CN)(6)](4-) linkers, featuring regular (1) or distorted (2) octahedral net skeletons. Upon dehydration, both compounds show reversible escape and binding processes toward water or methanol molecules. Magnetic susceptibility measurements of 1 and 2 reveal strong antiferromagnetic [J = -199(1) cm(-1)] or strong ferromagnetic [J = +153(1) cm(-1)] couplings between the copper(II) ions through the µ-O-alkoxo atoms in 1 or 2, respectively. The differences in magnetic behavior are explained in terms of the dependence of the magnetic coupling constant on the Cu-O-Cu bridging angle. Compounds 1 and 2 also act as efficient catalyst precursors for the mild oxidation of cyclohexane by aqueous hydrogen peroxide to cyclohexanol and cyclohexanone (homogeneous catalytic system), leading to maximum total yields (based on cyclohexane) and turnover numbers (TONs) up to about 22% and 470, respectively.

Copper(II) coordination polymers derived from triethanolamine and pyromellitic acid for bioinspired mild peroxidative oxidation of cyclohexane.

The new inorganic 1D coordination polymer [Cu2(H3tea)2(mu4-pma)]n has been prepared, via self-assembly in aqueous medium, from copper(II) nitrate, triethanolamine (H3tea), pyromellitic acid (H4pma) and lithium hydroxide, and characterized by IR spectroscopy, elemental and single-crystal X-ray diffraction analyses. This compound and the related 2D polymer [Cu2(mu-H2tea)(2){mu3-Na2(H2O)4}(mu6-pma)]n.10nH2O are shown to mimic the alkane partial oxidation activity of the multicopper particulate methane monooxygenase, acting as catalysts precursors for the peroxidative oxidation of cyclohexane into cyclohexanol and cyclohexanone, by hydrogen peroxide (as green oxidant) and at room temperature in acidic MeCN/H2O medium. An overall yield (based on cyclohexane) of 29% has been achieved.

New diamondoid-like [Cu3B(µ-O)6] core self-assembled from Bis-Tris biobuffer for mild hydrocarboxylation of alkanes to carboxylic acids.

The new tricopper(II) complex [Cu(3)(µ(3)-BO)(H(3)L)(3)][BF(4)]·2H(2)O (1) with an unprecedented diamondoid-like [Cu(3)B(µ-O)(6)] core has been easily generated by self-assembly in an aqueous medium from Cu(NO(3))(2), NaBF(4), NaOH and Bis-Tris (H(5)L) biobuffer, (HOCH(2))(3)CN(CH(2)CH(2)OH)(2). Compound 1 efficiently promotes the mild single-pot hydrocarboxylation, by CO and H(2)O, of various linear and cyclic C(n) (n = 2-8) alkanes into the corresponding C(n+1) carboxylic acids.

Self-assembled copper(II) coordination polymers derived from aminopolyalcohols and benzenepolycarboxylates: structural and magnetic properties.

The new copper(II) or copper(II)/sodium(I) 1D coordination polymers [Cu2(Hmdea)2(mu-H2O)(mu2-tpa)]n.2nH2O (1), [Cu2(H2tipa)2(mu2-ipa)]n.4nH2O (2), [Cu2(H2tea)2Na(H2O)2(mu2-tma)]n.6nH2O (3), [Cu2(H2tea)2(mu2-ipa)]n.nH2O (4a), and [Cu2(H2tea)2{mu3-Na(H2O)3}(mu3-ipa)]n(NO3)n.0.5nH2O (4b) have been prepared in aqueous medium by self-assembly from copper(II) nitrate, aminopolyalcohols [methyldiethanolamine (H2mdea), triisopropanolamine (H3tipa), and triethanolamine (H3tea)] as main chelating ligands and benzenepolycarboxylic acids [terephthalic (H2tpa), isophthalic (H2ipa), and trimesic (H3tma) acid] as spacers. They have been characterized by IR spectroscopy, elemental and single-crystal X-ray diffraction analyses, the latter indicating the formation of unusual multinuclear metal cores interconnected by various benzenepolycarboxylate spacers, leading to distinct wavelike, zigzag, or linear 1D polymeric metal-organic chains. These are further extended to 2D or 3D hydrogen-bonded supramolecular networks via extensive interactions with the intercalated crystallization water molecules. The latter are associated, also with aqua ligands, by hydrogen bonds resulting in acyclic (H2O)3 clusters in 1, (H2O)8 clusters in 2, infinite 1D water chains in 3, and disordered water-nitrate associates in 4b, all playing a key role in the structure stabilization and its extension to further dimensions. Variable-temperature magnetic susceptibility measurements have shown that 1-4 exhibit a moderately strong ferromagnetic coupling through the alkoxo bridge. The small Cu-O-Cu bridging angle and the large out-of-plane displacement of the carbon atom of the alkoxo group accounts for this behavior. The magnetic data have been analyzed by means of a dinuclear and a 1D chain model, and the magnetic parameters have been determined. The magnetic exchange coupling in 3, to our knowledge, is the highest found in alkoxo-bridged copper(II) complexes.