Die Temperaturabhängigkeit der magnetischen Suszeptibilität einiger Elementdipyridyle

Abstract

Mit 9 Abbildungen I n h a l t s u b e r s i c h t : Es wurde die Temperaturabhiingigkeit der magnetischen Suszeptibiliet und die paramagnetische Elektronenresonanz von 12 Elbmentdipyridylen untersucht.Bei den Hauptgruppenverbindungen und ScDipy, ist der Magnetismua infolge Spinwechselwirkung von Radikalanionen stark temperaturabhgngig. In den ubrigen Ubergangsmetallverbindungen ist die Temperaturabhangigkeit weniger ausgepragt. Es wird versucht, sie auf Grund qualitativer Betrachtungen nach der LCAO-&TO-Theorie zu erklaren.A b s t r a c t : The temperature dependence of the magnetic susceptibility and the EPR were investigated on 12 element dipyridyls. The magnetism of the main group compounds and of ScDipy, depends strongly on the temperature, owing to spin interaction of radical anions. l'he temperature dependence is less marked in other transition metal compounds. It is attempted to explain the dependence by means of the LCAO-NO theory.

Electronic Structures of the Electron Transfer Series [M(bpy)3]n, [M(tpy)2]n, and [Fe(tbpy)3]n (M = Fe, Ru; n = 3+, 2+, 1+, 0, 1–): A Mössbauer Spectroscopic and DFT Study

“…[11a] We note that the present DFT calculations yield optimized structures in which the supporting ligands are fully equivalent (i.e. [29,30] Using these data, Inoue, Horiba, and Hara obtained metal-mediated antiferromagnetic radical-radical coupling constants of J Al = -79 cm -1 and J Sc = -139 cm -1 for the exchange coupling interaction between two (bpy · ) 1radicals, thereby yielding an S = 1/2 ground state. Unfortunately, these monocationic complexes have yet to be characterized by X-ray crystallography, which could resolve the matter.…”

“…This has prevented examination of the temperature dependence of its molar magnetic susceptibility 10a. In contrast, the neutral complexes [Al III (bpy · ) 3 ] 0 and [Sc III (bpy · ) 3 ] 0 , each containing three (bpy · ) 1– radical anions ( S = 1/2) and a d 0 metal center, do not contain such contaminants and the magnetic susceptibility of [Al III (bpy · ) 3 ] · 1/2THF and [Sc III (bpy · ) 3 ] 0 have been studied in the temperature ranges 4–300 and 80–350 K, respectively 29,30. Using these data, Inoue, Horiba, and Hara obtained metal‐mediated antiferromagnetic radical–radical coupling constants of J Al = –79 cm –1 and J Sc = –139 cm –1 for the exchange coupling interaction between two (bpy · ) 1– radicals, thereby yielding an S = 1/2 ground state 32.…”

“…[Al III (bpy · ) 3 ] 0 1/2 -79 -51 [29] [Sc III (bpy · ) 3 ] 0 1/2 -139 -162 [30] [Zn II (tpy · ) 2 ] 0 1 n.m. +11 [33] [Fe II (bpy · ) 2 (bpy 0 )] 0 1 n.m. +26 this work [Fe II (bpy · ) 3 ] 1-3/2 n.m. +49 this work [Ru II (bpy · ) 2 (bpy 0 )] 0 0 -160 -46 (-161, -231) [25] [Ru II (bpy · [27] [Cr III (bpy · ) 2 (bpy 0 )] 1+ 1/2 a.f.Ͼ|300| [27] [Cr III (bpy · )(bpy 0 ) 2 ] 2+ 1 a.f.Ͼ|300| [27] [a] Spin ground state. [b] Magnetic coupling constant, J in cm -1 using the spin-Hamiltonian Ĥ = -2J Σ S M ·S i (S i = 1/2; i = 1,2,3); a.f.…”

Recent advances in hexacoordinate silicon with pyridine-containing ligands: Chemistry and emerging applications

“…The calculated coupling constant for singlet diradical state of Si(bpy)3 0 is close to the experimentally reported value of Jexp = -374 cm -1 . [50] The redox activity of polypyridylsilicon(IV) complexes were explored using cyclic voltammetry. [45] [Si(bpy)3](PF6)4 can be reduced electrochemically with up to 6 electrons ( Table 5).…”

Synthesis, Structure, and Properties of Al(Rbpy)3 Complexes (R = t-Bu, Me): Homoleptic Main-Group Tris-bipyridyl Compounds

“…Both complexes contain Ga 3+ metal ions, where the latter complex contains two neutral bpy ligands and one radical bpy anion as discussed below. Group 3 [Sc­(bpy) 3 ] 0 and group 14 [Si­(bpy) 3 ] n (where n = 4+ to 1+) have been described but not structurally characterized. − One heptacoordinate tris-bpy complex of thallium (Tl­(bpy) 3 dmso, dmso = dimethylsulfoxane) has been prepared and crystallographically characterized, but it contains an additional dmso ligand in the Tl coordination sphere . Although there is a lack of main-group homoleptic tris bpy complexes, other redox-active bidentate N-donor ligands have been structurally characterized containing aluminum centers .…”