Manganese (III) cyclam complexes with aqua, iodo, nitrito, perchlorato and acetic acid/acetato axial ligands

Abstract

The syntheses, structures and magnetic properties of five new manganese (III) cyclam complexes, trans-[Mn(cyclam)(OH 2) 2](CF 3SO 3) 3 · H 2O, trans-[Mn(cyclam)I 2]I, trans-[Mn(cyclam)(ONO) 2]ClO 4, trans-[Mn(cyclam)(OClO 3) 2]ClO 4 and trans-[Mn(cyclam)(CH 3COO)(CH 3COOH)](ClO 4) 2, are reported. Cyclam is the tetradentate amine ligand 1,4,8,11-tetraazacyclotetradecane. The complexes all exhibit pronounced tetragonal elongation of the coordination octahedron with the four cyclam nitrogens occupying the four equatorial positions. The magnetic properties are consistent with the formulation of the complexes as high-spin d 4 systems. trans-[Mn(cyclam)(OH 2) 2](CF 3SO 3) 3 · H 2O is shown to be a convenient starting material for the syntheses of trans cyclam complexes. [Mn(cyclam)(CH 3COO)(CH 3COOH)](ClO 4) 2 exhibits extremely short intermolecular hydrogen bonds resulting in a pseudo-chain structure. The tilt of the axial ligands with respect to the equatorial plane containing the manganese and the cyclam nitrogen atoms is discussed.