Synthesis and Magnetic Study of μ1,1‐Azido‐Bridged Dinuclear Manganese(II) Complexes Based on Tripyridyl Ligands

Abstract

AbstractThree azido‐bridged MnII complexes of formulas [Mn2(N3)4(ttp)2] (1), [Mn2(N3)4(ttp‐N3)2] (2) and [Mn2(N3)4(ttp‐N3)2]3[MnIII(ttp‐N3)(N3)3]2 (3), where ttp and ttp‐N3 represent 4′‐p‐tolyl‐2,2′:6′,2″‐terpyridine and 4′‐p‐azidomethylphenyl‐2,2′:6′,2″‐terpyridine, were synthesized and characterized by single‐crystal X‐ray diffraction analysis and magnetic studies. The Mn ions in complexes 1 and 2 are coordinated by three N atoms of the ttp or ttp‐N3 ligands, and they are connected by double end‐on (EO) azide ligands; this forms a dinuclear MnII system with Mn–N–Mn bridging angles of 103.5 and 103.1°. The Br atoms of the –CH2Br ligands were replaced by azido groups during the formation of complexes 2 and 3. The structure of complex 3 comprises two structurally similar MnII dimers with double end‐on bridging azide groups and one mononuclear MnIII structure. The bridging Mn–N–Mn angles in 3 are 104.2, 105.1, and 106.73°. Magnetic studies indicate the presence of intramolecular ferromagnetic superexchange. The strength of ferromagnetic coupling within the Mn2 cores in 1–3 is dependent on the Mn–N–Mn bridging angles. The magnetic coupling constants for intermolecular exchange are 2.46(4), 2.25(2), and 1.92(4) cm–1 for 1, 2, and 3, respectively, on the basis ofHamiltonian Ĥ = –2JŜ1Ŝ2.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)