Nickel Complexes with N2O Donor Ligands: Syntheses, Structures, Catalysis and Magnetic Studies

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)