Template synthesis and characterisation of a copper(II) complex of a half-cyclised tetraaza ligand derived from 1,8-diaminonaphthalene, nitroethane and formaldehyde

991-996Reaction of Cu(BF4)2.xH2O with 1,8-diaminonaphthalene, nitroethane and formaldehyde in ethanol in the presence of triethylamine yields an air sensitive copper(II) complex of 1,3-bis (8-aminonaphthyl-1-amino)- 2-methyl-2-nitropropane (L) as Cu(L)-(BF4)2.C2H5OH, 1. Molecular mechanics calculations coupled with the solution conductivity data indicate a distorted square pyramidal N4F coordination sphere for the copper atom in 1 with the fluorine atom occupying the apical position and the metal atom lifted a bit from the N4 plane. This is supported by the rhombic EPR spectra of <b style="mso-bidi-font-weight: normal">1(g3= 2.389, g2 = 2.069 and g1 = 2.023 ; A3 = 137.9 × 10-4 cm-1 , A2 = 18.1 x 10-4 cm-1 and A1 = 17.7 x 10.4 cm-1). The complex <b style="mso-bidi-font-weight: normal">1 undergoes a somewhat irreversible two-electron ligand oxidation at 0.36 V vs SCE in dimethylformanide. The cyclic counterpart of 1 is not at all formed in the synthetic scheme adopted here.