The first trinuclear manganese triplesalen complex: Synthesis, structural, and magnetic characterization of [(talenNO2){MnIII(DMSO)2}3](ClO4)3

Abstract

The reaction of the nitro-substituted triplesalen ligand H(6)talen(NO2) with Mn(ClO4)(2)center dot 6H(2)O in CH3CN in the presence of Et3N and DMSO results in the formation of [(talen(NO2)){Mn-III(DMSO)(2)}(3)](ClO4)(3) (1) which has been characterized by elemental analysis, FTIR, UV-vis-NIR, ESI-MS, single-crystal X-ray diffraction, and magnetic measurements. The triplesalen ligand (talen(NO2))(6-) provides three salen-like coordination environments bridged in a meta-phenylene arrangement by a phloroglucinol backbone. The coordination environment of each Mn-III ion is completed by two O-bonded DMSO molecules. The folding of the triplesaten ligand results in an overall dish-like geometry for the trication in 1. The magnetic characterization has been performed by temperature dependent magnetic susceptibility measurements and variable temperature-variable field (VTVH) magnetization data in order to determine both the exchange couplings J between the S-i = 2 ion and the local zero-field splittings D-i. Simulations to the appropriate spin-Hamiltonian using a full-matrix diagonalization approach provided a weak antiferromagnetic interaction J = -0.30 +/- 0.05 cm(-1) but a strong magnetic anisotropy expressed by D = -4.0 +/- 0.4 cm(-1). The potential applications of 1 and forthcoming members of this new family of trinuclear manganese triplesalen complexes in molecule-based magnetism and homogenous catalysis are discussed.