New cyanide-bridged MnIII–MIII heterometallic dinuclear complexes constructed from [MIII(AA)(CN)4]− building blocks (M = Cr and Fe): synthesis, crystal structures and magnetic properties

摘要: Three MnIII–MIII (M = Cr and Fe) dinuclear complexes have been obtained by assembling [MnIII(SB)(H2O)]+ [MIII(AA)(CN)4]− ions, where SB is the dianion of Schiff-base resulting from condensation 3-methoxysalicylaldehyde with ethylenediamine (3-MeOsalen2−) or 1,2-cyclohexanediamine (3-MeOsalcyen2−): [Mn(3-MeOsalen)(H2O)(µ-NC)Cr(bipy)(CN)3]·2H2O (1), [Mn(3-MeOsalen)(H2O)(µ-NC)Cr(ampy)(CN)3][Mn(3-MeOsalen)(H2O)2]ClO4·2H2O (2) [Mn(3-MeOsalcyen)(H2O)(µ-NC)Fe(bpym)(CN)3]·3H2O (3) (bipy 2,2′-bipyridine, ampy 2-aminomethylpyridine bpym 2,2′-bipyrimidine). The [M(AA)(CN)4]− unit in 1–3 acts as a monodentate ligand towards manganese(III) ion through one its four cyanide groups. exhibits an elongated octahedral stereochemistry tetradentate building equatorial plane water molecule cyanide-nitrogen atom filling axial positions. Remarkably, neutral mononuclear complex [Mn(3-MeOsalen)(H2O)2]ClO4 co-crystallizes heterobimetallic 2. values distance across bridging are 5.228 5.505 5.265 A (3). packing units crystal governed self-complementarity [Mn(SB)(H2O)]+ moieties, which interact each other hydrogen bonds established between aqua fragment set phenolate- methoxy-oxygens adjacent one. magnetic properties three investigated temperature range 1.9–300 K. Weak antiferromagnetic interactions MnIII MIII ions cyanido bridge were found: JMnM −5.6 −0.63 −2.4 cm−1 Hamiltonian being defined H −JSMn·SM. Theoretical calculations based on density functional theory (DFT) used to substantiate both nature magnitude exchange observed also analyze dependence coupling structural parameters within MnIII–N–C–MIII motif 1–3.