Syntheses, Structures and Magnetic Properties of Heterobridged Dinuclear and Cubane-Type Tetranuclear Complexes of Nickel(II) Derived from a Schiff Base Ligand

Syntheses, structures and magnetic properties of a hetero-bridged mu-phenoxido-mu(1,1)-NCO dinickel(II) compound [Ni-2(II)-(HL)(3)(mu-NCO)]center dot 2H(2)O (1) and a heterobridged bis(mu(3)-phenoxido)bis(mu(3)-alkoxido)tetranickel(II) system, [Ni-4(II)(L)(2)(HL)(2)-(SeCN)(2)(H2O)(2)]center dot C3H7NO center dot 4H2O (2), containing a cubane-type (Ni4O4)-O-II core, derived from the tetradentate Schiff base compartmental ligand N-(2-hydroxyethyl)-3-methoxysalicylaldimine (H2L) were described. Compounds 1 and 2 crystalhze in triclinic P (1) over bar and monoclinic P2(1)/c systems, respectively. Compound 2, in which the Ni4O4 cubane core is composed of two mu(3)-phenoxido and two mu(3)-alkoxido moieties, represents the sole example of this type. The variable-temperature (2-300 K) magnetic susceptibilities and magnetizations of these two compounds were measured. The interaction between the metal centres in dinuclear compound 1 is weak ferromagnetic, resulting in an S-T = 2 ground state at 2 K. The overall interaction observed in 2 is weak ferromagnetic, leading to an unusual ST = 3 ground state. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)