SYNTHESIS AND CHARACTERIZATION OF COBALT(II), NICKEL(II) AND ZINC(II) COMPLEXES OF A 14-MEMBERED CIS-N2S2 DIBENZO MACROCYCLE WITH 2 PENDANT PYRIDYLMETHYL GROUPS

The complexes [ML(1)](2+) with M=cobalt(II), nickel(II) and zinc(II) and L(1)=8,11-bis(2-pyridylmethyl)5,6,7,8,9,10,16,17 -octahydro-dibenzo[e,m][1,4]dithia[8,11]diazacyclotetradecine have been prepared as perchlorate salts. [CoL(1)](2+) and [NiL(1)](2+) were characterized by UV-Vis spectroscopy and cyclic voltammetry. [CoL(1)](2+) is stable in air. The crystal structure of [NiL(1)](ClO4)(2) . H2O shows a distorted octahedral geometry with cis-orientation of chemically identical donor atoms. Intraligand strain prevents short Ni-S bonds. In solution [ZnL(1)](2+) takes up atmospheric carbon dioxide and transforms to the dinuclear complex [(mu-CO3)(ZnL(1))(2)](ClO4)(2), the crystal structure of which has been elucidated as well. The zinc atoms, which are situated outside the macrocyclic ring, are unsymmetrically bridged by the mu-carbonato group.