[M(II)(H(2)dapsc)]-[Cr(CN)(6)] (M = Mn, Co) Chain and Trimer Complexes: Synthesis, Crystal Structure, Non-Covalent Interactions and Magnetic Properties

Four new heterometallic complexes combining [M(II)(H(2)dapsc)](2+) cations with the chelating H(2)dapsc {2,6-diacetylpyridine-bis(semicarbazone)} Schiff base ligand and [Cr(CN)(6)](3−) anion were synthesized: {[M(II)(H(2)dapsc)]Cr(III)(CN)(6)K(H(2)O)(2.5)(EtOH)(0.5)}(n)·1.2n(H(2)O), M = Mn (1) and Co (2), {[Mn(H(2)dapsc)](2)Cr(CN)(6)(H(2)O)(2)}Cl·H(2)O (3) and {[Co(H(2)dapsc)](2)Cr(CN)(6)(H(2)O)(2)}Cl·2EtOH·3H(2)O (4). In all the compounds, M(II) centers are seven-coordinated by N(3)O(2) atoms of H(2)dapsc in the equatorial plane and N or O atoms of two apical –CN/water ligands. Crystals 1 and 2 are isostructural and contain infinite negatively charged chains of alternating [M(II)(H(2)dapsc)](2+) and [Cr(III)(CN)(6)](3−) units linked by CN-bridges. Compounds 3 and 4 consist of centrosymmetric positively charged trimers in which two [M(II)(H(2)dapsc)](2+) cations are bound through one [Cr(III)(CN)(6)](3−) anion. All structures are regulated by π-stacking of coplanar H(2)dapsc moieties as well as by an extensive net of hydrogen bonding. Adjacent chains in 1 and 2 interact also by coordination bonds via a pair of K(+) ions. The compounds containing Mn(II) (1, 3) and Co(II) (2, 4) show a significant difference in magnetic properties. The ac magnetic measurements revealed that complexes 1 and 3 behave as a spin glass and a field-induced single-molecule magnet, respectively, while 2 and 4 do not exhibit slow magnetic relaxation in zero and non-zero dc fields. The relationship between magnetic properties and non-covalent interactions in the structures 1–4 was traced.