Assembly: Molecular Recognition Between a Trinuclear Mn Triplesalen Complex and a fac-Triscyano Cr Complex
نویسندگان
چکیده
The reaction of the tris(tetradentate) triplesalen ligand H6talen 2, which provides three salen-like coordination environments bridged in a meta-phenylene arrangement by a phloroglucinol backbone, with Mn salts under aerobic conditions, affords, in situ, the trinuclear Mn triplesalen complex [(talen){Mn(solv)n}3] . This species then reacts with [(Me3tacn)Cr(CN)3] to form the tetranuclear complex [{(talen )Mn3}{(Me3tacn)Cr(CN)3}] 3+ ([Mn3Cr ]). The regular ligand folding observed in the trinuclear triplesalen complex preorganizes the three metal ions for the reaction with three facially coordinated nitrogen atoms of [(Me3tacn)Cr(CN)3]. [{(talen 2)(Mn(MeOH))3}{(Me3tacn)Cr(CN)3}](ClO4)3 (1) was characterized by infrared spectroscopy, elemental analysis, mass spectrometry, electron absorption spectroscopy, and magnetic measurements. The molecular structure was established for the acetate-substituted derivative [{(talen)(Mn(MeOH))2(Mn (OAc))}{(Me3tacn)Cr(CN)3}](ClO4)2 (2) by single-crystal X-ray diffraction. Variable-temperature-variable-field and μeff versus T magnetic data have been analyzed in detail by full-matrix diagonalization of the appropriate spin-Hamiltonian, consisting of isotropic exchange, zero-field splitting, and Zeeman interaction components. Satisfactory reproduction of the experimental data has been obtained for the parameters JMn-Cr =-0.12( 0.04 cm, JMn-Mn =-0.70( 0.03 cm, and DMn =-3.0 ( 0.4 cm. These generate a triply degenerate pseudo St = 7/2 spin manifold, which cannot be appropriately described by a giant spin model and which exhibits a weak easy-axis magnetic anisotropy. This is corroborated by the onset of a frequency-dependent χ00 signal at low temperatures, demonstrating a slow relaxation of the magnetization indicative of 1 being a single-molecule magnet. Comparing the properties to those of the heptanuclear analogue [{(talen)Mn3}2{Cr (CN)6}] 3+ ([Mn6Cr ]) formed by the reaction of 2 equiv of [(talen){Mn(solv)n}3] 3+
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Spin resolved photoelectron spectroscopy of [Mn6(III)Cr(III)]3+ single-molecule magnets and of manganese compounds as reference layers.
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