Bimetallic metal-organic frameworks containing the [M(2,x-pdc) 22-] (M = Cu, Pd, Pt; x = 4, 5) building block - Synthesis, structure, and magnetic properties

Abstract

New bimetallic coordination polymers containing the [Cu(2,x-pdc) 22-] (pdc = pyridine dicarboxylate, NC5H 3(CO2)2; x = 4,5) 'metalloligand' unit, linked by Mn11 or Co11 cations, have been obtained by hydrothermal synthesis. The metalloligand species K2[Cu(2,x-pdc) 2(OH2)n].mH2O (1, 2) were reacted under basic conditions with MnCl2 at 200 °C to form the compounds [CuMn(2,x-pdc)2] (3, x = 4; 4, x = 5), which are unexpectedly isostructural. Similar reaction with CoCl2 gave [Co 3Cu2(2,4-pdc)4(μ4-OH)2(OH 2)]2 (5), which has a ladder-like framework based on Co-hydroxide chains, and the 2-dimensional sheet polymer [CoCu(2,4-pdc) 2(OH2)4] (6). A related CuII-only chain compound, [Cu2(2,5-pdc)2(OH2) 2]-4H2O (7) is also reported. The Compounds 1-7 have been structurally characterized by single crystal X-ray diffraction. The DC magnetic susceptibilites of 3 - 6 and [M3M′2(2,4-pdc) 4(μ4-OH)2(OH2)] (8: M = Co, M′ = Pd; 9: M = Co, M' = Pt; 10: M = Ni, M′ = Pd; 11: M = Ni, M′ = Pt) have been studied by SQUID magnetometry; 3 and 4 undergo antiferromagnetic ordering at low temperature, 5, 8 and 9 are metamagnets, 6 exhibits weak ferromagnetic exchange, while 10 and 11 show canted antiferromagnetism. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA,.