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

Abstract

Abstract Two new terephthalato‐bridged tetranuclear polymeric Ni II complexes, namely [Ni 4 L 4 1 (μ‐tp‐κ 4 ‐O)(H 2 O) 2 (μ‐tp‐κ 2 ‐O)] · 2C 2 H 5 OH · CH 3 OH · 3H 2 O ( 1 ) and [Ni 4 L 4 2 (μ‐tp‐κ 4 ‐O)(H 2 O) 2 (μ‐tp‐κ 2 ‐O)] · 3H 2 O ( 2 ) [L 1 = N ‐(3‐aminopropyl)‐5‐bromosalicylaldimine and L 2 = N ‐(3‐aminopropyl)salicylaldimine], are reported along with the syntheses and structures of the dicyanoargentate‐bridged polymeric complexes [Ni(L 1 )(H 2 O){Ag(CN) 2 }] α ( 3 ) and [Ni(L 3 )(MeOH){Ag(CN) 2 }] α ( 4 ) [L 3 = 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 Ni II centers.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)