Dinickel(II), dizinc(II) and dilead(II) complexes of a pyridazine-containing Schiff-base macrocycle

Abstract

The study of the mid-late first row transition metal co-ordination chemistry of the pyridazine-containing Schiff-base macrocycle L1 [derived from the (2+2) condensation of 3,6-diformylpyridazine and 1,3-diaminopropane] has been completed. Transmetallation reactions of Pb2(4+4)4 (1) under appropriate conditions have led to the formation of the following complexes, [Ni2L1(NCS)2(SCN)2] (3), {Pb2L1}2(l3-OH)26 (4), and Zn2L1(CH3CN)44 (5Æ4CH3CN), all of which have been structurally characterised. The analogous triflate salt of 5, Zn2L14 (6), can only be obtained by template reaction, as transmetallation of 1 with Zn(CF3SO3)2 Æ6H2O gave 5, albeit in reduced yield. Attempts to synthesise pure Fe2L1(CH3CN)44 (7) using the transmetallation procedure, from either Pb2(4+4)4 or Zn2L1(CH3CN)44, were unsuccessful. The electrochemical studies carried out on Zn2L14 (5) revealed multiple reduction processes and associated oxidations, but no processes corresponding to oxidation of 5.
2004 Elsevier B.V. All rights reserved.