New pyridine-2,3,5,6-tetracarboxylato (H4pdtc) complexes: Synthesis, crystal structures and magnetic properties of K2[Mn(H2O)(pdtc)]·3H2O 1, Na2[M3(H2O)6(pdtc)2]·6H2O (M=Mn 2, Co 3)

Three new pyridine-2,3,5,6-tetracarboxylato (H₄pdtc) complexes K₂[Mn(H₂O)(pdtc)]·3H₂O 1, Na₂[M₃(H₂O)₆(pdtc)₂]·6H₂O (M=Mn 2, Co 3) were obtained and characterized by single-crystal X-ray diffraction methods and magnetic measurements. The characteristic building blocks of 1–3 are the pdtc bridged stair-like chains ∞¹([M(H₂O)](pdtc){sub 3/3})²⁻, which results from the six-coordinated transition metal atoms bridged by pdtc⁴⁻ ligands. The infinite chains in 1 are assembled by hydrogen bonds into 2D supramolecular networks, which are held together by (4·8²) topological K⁺–H₂O networks to complete 3D architecture. While the stair-like chains in 2 and 3 are interconnected by trans-[M(H₂O)₄]²⁺ moieties to 2D polymeric layers, which are bridged by dimeric [Na₂(μ-H₂O)₂(H₂O)₂]²⁺ moieties to build up 3D framework. The magnetic properties of 1–3 were analyzed on the basis of (i) linear trinuclear M₃ models and (ii) the free Mn²⁺ and Co²⁺ ions with the zero-field splitting effect and spin–orbit coupling effect, respectively. - Graphic abstract: Synopsis. The characteristic building blocks and magnetic model of K₂[Mn(H₂O)(pdtc)]·3H₂O 1 and Na₂[M₃(H₂O)₆(pdtc)₂]·6H₂O (M=Mn 2, Co 3). Highlights: • The characteristic building blocks of 1–3 are the pdtc bridged stair-like chains. • The compound 2 and 3 are interlinked by trans-[M(H₂O)₄]²⁺ moieties to 2D layers. • The magnetic behavior of 1 was analyzed with zero-field splitting effects.more » • The magnetic behaviors were modulated with linear trinuclear model for 2 and 3.« less