The magnetic properties of the tetrameric oxygen-bridged copper(l1) complexes [{CuX(OCH,CH,NR,)),] (1 ) (R = Me, X = NCO; R = Pr", X = NCO; and R = Bun, X = NCO or NCS) have been determined in the temperature range 3.4-300 K. The cubane-type complexes exhibit magnetic interactions between the single copper( 1 1 ) ions, which can be explained on the basis of the isotropic Heisenberg-Dirac-van Vleck model. The magnetism of (1 ; R = Me, X = NCO) can be explained on the basis of four non-interacting ' dimeric ' units with the exchange integrals J, = -65 f 3, J, = -0.6 f 2, J, = -0.3 f 2, and J, = -0.9 f 2 cm-l. A linear relationship between the exchange integral and the Cu-0-Cu bridge angle has been established for symmetric bridged complexes. The magnetic properties of (1 ; R = Pr", X = NCO; R = Bun, X = NCO or NCS) could be fitted with a theoretical equation assuming C,, symmetry. The resulting exchange integrals
Die magnetische Suszeptibilität von tetrameren Halogeno(2‐dialkylaminoäthanolato)kupfer(II)‐Komplexen (Halo en = Cl, Alkyl = Äthyl:(CuEtCl)4: Halogen = Cl, Br, Alkyl = n‐Butyl:(CuBuCl)4, γ‐(CuBuBr)4) wurde im Temperaturbereich von 2,6 t s 300 K gemessen. Die Ergebnisse zeigen, daß die chemisch nur wenig verschiedenen Kubantypcluster (Molekülsymmetrie C2 bzw. C1) unterschiedliche magnetische Eigenschaften besitzen. Während bei (CuEtCl)4 antiferromagnetische Spinkopplung mit einem S' = 0‐Grundzustand vorliegt, zeigen (CuBuCl)4 und γ‐(CuBuCI)4 ferromagnetische Spinkopplung, wobei der S' = 2‐Grundzustand unterhalb 40 K vollständig besetzt ist.—Für (CuEtCl)4 konnten die intramolekularen Kopplungskonstanten mit Hilfe des isotropen HDVV‐Modells bestimmt werden (J12 = ‐93 cm−1, J34 = ‐ 17,4cm−1, J13= +4cm−1, J14 = + 2 cm−1); für (CuBuCl)4 und γ‐(CuBuBr)4 gelang dieses nicht. Die magnetischen Momente von (CuBuCl)4 und γ‐(CuBuBr)4 sinken unterhalb 15 K unter den für einen S' = 2‐Grundzustand zu erwartenden Wert ab.
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