PUB - Publikationen an der Universität Bielefeld

The ligating properties of the 24-membered macrocyclic dinucleating hexaazadithiophenolate ligand (L-Me)(2-) towards the transition metal ions Cr-II, Mn-II, Fe-II, Co-II, Ni-II and Zn-II have been examined. It is demonstrated that this ligand forms an isostructural series of bioctahedral [(L-Me) M-II (2)(OAc)](+) complexes with Mn-II ( 2), Fe-II ( 3), Co-II ( 4), Ni-II ( 5) and Zn-II ( 6). The reaction of (L-Me)(2-) with two equivalents of CrCl2 and NaOAc followed by air-oxidation produced the complex [(L-Me) (CrH2)-H-III( OAc)](2+) ( 1), which is the first example for a mononuclear complex of (L-Me)(2-). Complexes 2 - 6 contain a central N3MII(mu-SR)(2)(mu-OAc) (MN3)-N-II core with an exogenous acetate bridge. The Cr-III ion in 1 is bonded to three N and two S atoms of (L-Me)(2-) and an O atom of a monodentate acetate coligand. In 2 - 6 there is a consistent decrease in the deviations of the bond angles from the ideal octahedral values such that the coordination polyhedra in the dinickel complex 5 are more regular than in the dimanganese compound 2. The temperature dependent magnetic susceptibility measurements reveal the magnetic exchange interactions in the [(L-Me) M-II (2)(OAc)](+) cations to be relatively weak. Intramolecular antiferromagnetic exchange interactions are present in the Mn-II (2), Fe-II (2) and Co-II (2) complexes where J =- 5.1, - 10.6 and similar to- 2.0 cm(-1) ( H=- 2JS(1)S(2)). In contrast, in the dinickel complex 5 a ferromagnetic exchange interaction is present with J =+ 6.4 cm(-1). An explanation for this difference is qualitatively discussed in terms of the bonding differences.