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

New bimetallic coordination polymers containing the [Cu(2,x-pdc)(2)(2-)] (pdc = pyridine dicarboxylate, NC5H3(CO2)(2); x = 4,5) 'metalloligand' unit, linked by Mn-II or Co-II cations, have been obtained by hydrothermal synthesis. The metalloligand species K-2[Cu(2,x-pdc)(2)(OH2)(n)].mH(2)O (1, 2) were reacted under basic conditions with MnCl2 at 200 degrees 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 [Co3Cu2(2,4-pdc)(4)(mu(4)-OH)(2)(OH2)](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 Cu-11-only chain compound, [Cu-2(2,5-pdc)(2)(OH2)(2)].4H(2)O (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)(mu(4)-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.