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Two new terephthalato-bridged tetranuclear polymeric NiII complexes, namely [Ni4L41(μ-tp-κ4-O)(H2O)2(μ-tp-κ2-O)]·2C2H5OH·CH3OH·3H2O (1) and [Ni4L42(μ-tp-κ4-O)(H2O)2(μ-tp-κ2-O)]·3H2O (2) [L1 = N-(3-aminopropyl)-5-bromosalicylaldimine and L2 = N-(3-aminopropyl)salicylaldimine], are reported along with the syntheses and structures of the dicyanoargentate-bridged polymeric complexes [Ni(L1)(H2O){Ag(CN)2}]α (3) and [Ni(L3)(MeOH){Ag(CN)2}]α (4) [L3 = N-(3-amino-2,2-dimethylpropyl)-5-bromosalicylaldimine]. All four complexes are found to be effective heterogeneous catalysts for the epoxidation of alkenes such as styrene, α-methylstyrene and cyclohexene in the presence of tert-butyl hydroperoxide. The variable-temperature magnetic susceptibility measurements (300–2 K) of complex 1 show a fair degree of antiferromagnetic coupling between the NiII centers.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)