Bimetallic Metal‐Organic Frameworks Containing the ${\rm [M(2,}x-{\rm pdc)^{2-}_{2}}]$ (M = Cu, Pd, Pt; <i>x</i> = 4, 5) Building Block – Synthesis, Structure, and Magnetic Properties

Abstract

Abstract New bimetallic coordination polymers containing the ${\rm [Cu(2,}x-{\rm pdc)^{2-}_{2}}]$ (pdc = pyridine dicarboxylate, NC 5 H 3 (CO 2 ) 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 (OH 2 ) n ]· m H 2 O ( 1 , 2 ) were reacted under basic conditions with MnCl 2 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 CoCl 2 gave [Co 3 Cu 2 (2,4–pdc) 4 (μ 4 −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 (OH 2 ) 4 ] ( 6 ). A related Cu II ‐only chain compound, [Cu 2 (2,5−pdc) 2 (OH 2 ) 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 [M 3 M′ 2 (2,4−pdc) 4 (μ 4 −OH) 2 (OH 2 )] ( 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.