Synthesis and Characterization of Binuclear Schiff Base Complexes of Nickel, Copper, and Manganese.

Binuclear complexes of Ni, Cu and Mn have been synthesized and characterized. The reaction of bissalicylaldehyde complexes of nickelII and copperII with m-xylylenebis-2-1,3-propanediamine 3 result in the formation of 5 and 7 respectively, while the reaction of managaneseII acetate with salicylaldehyde and 3 results in the formation of 6a. The nickel complex, 5, undergoes a quasireversible two-electron transfer at -1.47 V vs SCE attributable to the nickelII-nickelI couple. The binuclear nickelI complex can be generated from 5 both electrochemically and chemically, and has been shown by infrared analysis to form adducts of CO and MeNC. Magnetic susceptibility measurements by the Faraday method show the manganese and copper complexes 6a and 7 have solid state room temperature moments of 5.47 and 1.92 B.M. per metal center, respectively, while the solution magnetic moment of the binuclear copper complex 7 is found by the Evans method to be 1.49 B.M. per copper center. This reduced magnetic moment relative to the moment for mononuclear Cusalprn1.79 B.M suggests a weak magnetic interaction between the two copper centers in the binuclear copper complex 7.