MONONUCLEAR BARIUM AND DINUCLEAR COPPER(II) COMPLEXES OF A 24-MEMBERED BIBRACCHIAL TETRAIMINE SCHIFF-BASE MACROCYCLE DERIVED FROM N,N-BIS(2-AMINOETHYL)-2-METHOXYETHYLAMINE

The X-ray structure of a mononuclear barium complex of the bibracchial tetraimine Schiff-base macrocycle derived from the cyclocondensation of 2,6-diacetylpyridine and NN-bis(2-aminoethyl)-2-methoxyethylamine [monoclinic, space group P2/n (no. 13), a = 27.494(20), b = 14.120(13), c = 21.024(14) angstrom, beta = 91.68(57)-degrees, Z = 8] confirms that the macrocycle folds to present a molecular cleft within which the metal is co-ordinated. Transmetallation with Cu(II) gives a homodinuclear copper(II) complex the crystal structure of which [monoclinic, space group P2(1)/c, a = 14.807(6), b = 9.558(4), c = 17.432(8) angstrom, beta = 113.89(5)-degrees, Z = 2] shows that the copper(II) atoms are held by the 'head' units of the macrocycle, an opening of the cleft having occurred.