Strong electron-accepting methylviologen dication confined in magnetic hosts:: synthesis, structural characterization, charge-transfer and magnetic properties of {(MV)2[Ni(SCN)5]•Cl•2H2O}n and {(MV)[M(N3)2(SCN)2]}n (M = Mn, Co)

Three hybrid host-guest compounds {(MV)(2)[Ni(SCN)(5)]center dot Cl center dot 2H(2)O}(n) (1), {(MV)[Mn(N-3)(2)(SCN)(2)]}(n) (2) and {(MV)[Co(N-3)(2)(SCN)(2)]}(n) (3) (where MV2+ = methylviologen dication) have been obtained by self-assembly methods and characterized by X-ray crystallography, spectral methods and magnetic measurements. Compound 1 shows a quasi-two-dimensional structure which is formed by novel single thiocyanate-bridged Ni(II) chains connected through S center dot center dot center dot S interactions. Compounds 2 and 3 are isostructural, containing single mu(1,3)-azide bridged Mn(II)/Co(II) square layers. MV2+, as a strong electron-acceptor and a template, is embedded between the anionic layers in all three compounds. The charge-transfer (CT) interactions between MV2+ and the anionic hosts have been revealed by structural analysis and UV-vis diffuse reflection spectroscopy. The magnetic studies of the compounds show antiferromagnetic interactions between adjacent metal ions (J = -34.52(7) cm(-1) for 1, J = -3.90(2) cm(-1) for 2 and J = -10.96(6) cm(-1) for 3).