Structural, magnetic and related attributes of some oximate-bridged tetranuclear nickel(II) rhombs and a dinuclear congener

2CH3NO2, 1b; Solv = 2H2O·2C4H8O2, 1c), {Ni(Sdien)}2(MU3-OH)2{Ni2(Moda)4}(ClO4)2·H2O (2), {Ni(Odien)}2(MU3-OH)2{Ni2(Moda)4}(ClO4)2·0.6H2O (3), {Ni(Dien)}2(MU3-OH)2{Ni2(Inaf)4}(ClO4)2·CH3NO2(4) and {Ni(Odien)}2(MU3-OH)2{Ni2(Inaf)4}(ClO4)2·2NaClO4·2H2O (5) and the dinuclear complex (Ni{Odien})2(Moda)2(ClO4)2(6) have been prepared (Dien = 1,5-diamino-3-azapentane, Odien = 1,5-diamino-3-oxapentane, Sdien = 1,5diamino-3-thiapentane, ModaH = butane-2,3-dione monooxime, InafH = phenylglyoxaldoxime). X-ray examination revealed similar structures for 1a, 1b, 1c, 2 and 3, with a rhombic chair(out-of-phase butterfly) arrangement of the four nickel(II) atoms and two hydroxo-bridges. The complexes were examined by magnetochemistry, UV-VIS spectroscopy and voltammetry. 1-3 display antiferromagnetic coupling of the central with the terminal nickel(II) atoms and ferromagnetic spin alignment between the central nickel(II) atoms. In contrast, all the spin exchanges in 4 and 5 were found to be antiferromagnetic, as is the coupling in dinuclear 6.