Two Binuclear Cyanide-bridged Cr(III)-Mn(III) Complexes Based-on [Cr(2,2′-bipy)(CN)4]-Building Block: Synthesis, Crystal Structures and Magnetic Properties

Tetracyanide building block [Cr(2,2'-bipy)(CN)(4)](-) and two bicompartimental Schiff-base based manganese(III) compounds have been employed to assemble cyanide-bridged heterometallic complexes, resulting in two cyanide-bridged Cr-III-Mn-III complexes: [Mn(L-1)(H2O)][Cr(2,2'-bipy)(CN)(4)]center dot CH3OH center dot 2.5H(2)O (1) and [Mn(L-2)(H2O)][Cr((2,2'-bipy)(CN)(4)]center dot CH3OH center dot 3H(2)O (2) (L-1 equivalent to N,N'-(1,3-propylene)-bis(3-methoxysalicylideneiminate), L-2 equivalent to N, N'-ethylene-bis(3-ethoxysalicylideneiminate)). Single-crystal X-ray diffraction analysis shows their similar cyanide-bridged binuclear structures, in which the cyanide precursor acts as monodentate ligand connecting the manganese(III) ion. The binuclear complexes are self-complementary through coordinated aqua ligand and the free O-4 compartment from the neighboring complex, giving H-bond linking dimer structure. Investigations on magnetic properties reveal the antiferromagnetic coupling between the cyanide-bridged Cr(III) and Mn(III) ions. By using a Fortran program through numerical matrix diagonalization techniques, a best-fit to the magnetic susceptibilities of these two complexes leads to the magnetic coupling constants J equivalent to -5.95 cm(-1), j equivalent to -0.61 cm(-1) (1) and J equivalent to -4.15 cm(-1), j equivalent to -0.57 cm(-1) (2), respectively.