COPPER(II) COMPLEXES OF OPTICALLY-ACTIVE BINUCLEATING LIGANDS, N,N'-BIS[2-PYRIDYLMETHYL AND 2-(2-PYRIDYL)ETHYL]-(S)-MALAMIDE AND RELATED AMIDES

N,N'-Bis(2-pyridylmethyl)-3-hydroxyglutaramide [abbreviated as H-3(pmg )], optically active N,N'-bis{2-pyridylmethyl and 2-(2-pyridyl)ethyl}- (S)-malamide [H-3(lpm) and H-3(lpe), respectively], and the optically inactive analogues [H-3(ppm) and H-3(pem)] gave dimeric copper(II) com plexes [Cu2XL]. nH(2)O (L = lpm, lpe, pmm, pem, and pmg; X = an anioni c, exo-bridging ligand such as chloride, hydroxide, acetate (OAc), pyr azolate (pz), and nitrite ions). These complexes were characterized by magnetic susceptibilities, and electronic, circular dichroism, and in frared spectra. The amides act as a trivalent anionic ligand coordinat ing through the pyridine-and deprotonated amido-nitrogen atoms and thr ough the deprotonated, pendant alkoxo-oxygen atom bridging two copper ions. Many of the complexes were magnetically subnormal at room temper ature, the magnetic interaction between the two copper ions depending upon both L and the exo-bridges, X. The antiferromagnetic interaction increased in the order of X, Cl < OAc < OH < NO2 < pz. Temperature dep endence of the magnetic susceptibilities of some of the Ipm complexes ensured the order. A diamagnetic nickel(II) complex, Ni-2(pz)(lpm). 2H (2)O and a heterometallic CuNi(pz)(lpm). 2H(2)O were also obtained. Th e binuclear structure of Cu-2(pz)(ppm). 3H(2)O was confirmed by X-ray analysis. (C) 1997 Elsevier Science Ltd.