New Cu(ii) complexes based on the hydroxo-bridged dinuclear [Cu(OH) _2Cu] units: Step-like di- and trimerizations of [Cu(OH) _2Cu] units

摘要

Four new Cu(ii) complexes {[Cu_4(bpy)_4(OH) _4(H_2O)_2]}(NO_3)_2(C _7H_5O_2)_2·_6H_2O 1, {[Cu_4(bpy)_4(OH)_4(H_2O) _2]}(NO_3)_2(C_5H_6O _4)·8H_2O 2, {[Cu_4(bpy) _4(OH)_4(H_2O)_2]}(C_5H _6O_4)_2·16H_2O _3 and {[Cu _6(bpy)_6(OH)_6(H_2O) _2]}(C_8H_7O_2)6· 12H_2O 4 were synthesized (bpy = 2, 2′-bipyridine, H 2(C5H6O4) = glutaric acid, H(C 7H5O2) = benzoic acid, H(C8H 7O2) = phenyl acetic acid). The building units in 1-3 are the tetranuclear [Cu_4(bpy)_4(H_2O) _2(μ_2-OH)_2(μ3-OH) 2]4+ complex cations, and in 4 the hexanuclear [Cu 6(bpy)6(H2O)2(μ2-OH) 2(μ3-OH)4]6+ complex cations, respectively. The tetra- and hexanuclear cluster cores [Cu4(μ 2-OH)2(μ3-OH)2] and [Cu 6(μ2-OH)2(μ3-OH)4] in the complex cations could be viewed as from step-like di- and trimerization of the well-known hydroxo-bridged dinuclear [Cu2(μ2-OH) 2] entities via the out-of-plane Cu-O(H) bonds. The complex cations are supramolecularly assembled into (4, 4) topological networks via intercationic π?π stacking interactions. The counteranions and lattice H 2O molecules are sandwiched between the 2D cationic networks to form hydrogen-bonded networks in 1-3, while the phenyl acetate anions and the lattice H2O molecules generate 3D hydrogen-bonded anionic framework to interpenetrate with the (4, 4) topological cationic networks with the hexanuclear complex cations in the channels. The ferromagnetic coupling between Cu(ii) ions in the [Cu4(μ2-OH)2(μ3-OH) 2] cores of 1-3 is significantly stronger via equatorial-equatorial OH- bridges than via equatorial-apical ones. The outer and the central [Cu2(OH)2] unit within the [Cu6(μ 2-OH)2(μ3-OH)4] cluster cores in 4 exhibit weak ferromagnetic and antiferromagnetic interactions, respectively. Results about i.r. spectra, thermal and elemental analyses are presented.