Co(II), Ni(II) and Cu(II) mononuclear and polynuclear complexes influencedby the aliphatic spacer length of their O2N2O2 Schiff bases

M(H2Ln)(H2O)(x) and [M-2(L-n)(H2O)(x)](n) have been obtained by the electro chemical reaction of Co, Ni and Cu anodes with the O2N2O2 symmetrical ligan ds: N,N'-bis(3-hydroxysalicylidene)-1,2-diaminopropane H4L1, N,N ' -bis(3-h ydroxysalicylidene)-1,3-diaminopropane, H4L2, and N,N ' -bis(3-hydroxysalic ylidene)-1,4-diaminobutane H4L3. The preferential attainment of mono- or po lynuclear compounds seems to be conditioned by the aliphatic spacer length, among other factors. Spectroscopic and magnetic data suggest a distorted tetrahedral array in mo no- and polynuclear nickel complexes with H4L2 and H4L3. However, when the aliphatic spacer is shorter, as occurs in Ni(H2L1), physicochemical data ar e consistent with a square planar geometry. The EPR data for polynuclear co pper complexes display the characteristics of quasi-axial symmetry and show spin-spin interactions. Magnetic and electronic data point to high-spin di storted octahedral environments for Co(II) ions in [Co-2(L-3)(H2O)(4)](n). (C) 2001 Elsevier Science B.V. All rights reserved.