Synthesis, Crystal Structures, and Magnetic Properties of a Mono‐ and a Dinuclear Copper(II) Complex of the 2,4,6‐Tris(2‐pyridyl)‐1,3,5‐triazine Ligand

Abstract

AbstractThe reaction of 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine (tptz) with Cu(BF4)2·3H2O and N,N‐bis(3‐aminopropyl)methylamine (Medpt) yielded the monomeric complex [(tptz)CuII(Medpt)](BF4)2·2MeOH (1) whereas reaction of tptz with CuCl2·2H2O yielded the dinuclear complex [{CuIICl2}(tptz){CuIICl2(MeOH)}] (2). The molecular structures of 1 and 2 were established by single‐crystal X‐ray diffraction studies. The copper ion in complex 1 is elongated octahedral with the nitrogen atoms of Medpt and the triazine nitrogen atom of tptz in the equatorial positions, and the two pyridyl nitrogen atoms of tptz in axial positions. The two CuII ions in complex 2 are bridged by tptz, coordinating to Cu1 in a terpyridine‐like fashion and to Cu2 in a bipyridine‐like coordination mode. The triazine nitrogen atom bound to Cu1 is coordinated in an equatorial position whereas the triazine nitrogen atom bound to Cu2 is situated in the apical position. The equatorial plane of Cu1 is coplanar with the 1,3,5‐triazine plane whereas the equatorial plane of Cu2 is perpendicular to the 1,3,5‐triazine plane. Intermolecular interactions in the solid state result in both compounds in “dimeric units” due to hydrogen bonding. Both complexes were investigated by variable‐temperature magnetic susceptibility measurements. Through‐space dipolar couplings and/or weak through‐bond interactions in complex 1 result in a small intermolecular antiferromagnetic interaction (J = −0.09 cm−1). The intramolecular exchange coupling in the dinuclear complex 2 is antiferromagnetic (J = −2.5 cm−1). This antiferromagnetic interaction was analyzed in view of the molecular structure considering spin‐polarization, superexchange and orbital‐orthogonality. A spin‐polarization pathway seems to be the leading contribution which does not involve the 1,3 bridging pathway. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)