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Heterometallic complexes; Metal-metal interactions; Extended metal atom chains; Magnetic properties; Multiple bonds
Abstract:
The new heterometallic chain compound CrCrNi(dpa)(4)Cl(2)center dot Et(2)O (dpa = di-2,2'-pyridylamido and Et = ethyl) was synthesized by the reaction of Cr(2)(dpa)(4) and NiCl(2) in dry tetrahydrofurane. Recrystallization from CH(2)Cl(2)/ethyl ether yielded dark red, block-shaped crystals suitable for X-ray structure determination (P2(1)/c (no. 14), a = 159.29(1), b = 157.35(1), c = 169.76(1) pm, beta = 98.228(2)degrees, V = 4211.0(6) pm(3), Z = 4). The crystal structure of the title compound exhibits an orientational disorder of the CrCrNi chains, which has been elucidated by applying a well-defined split model. The Cr-Cr distance of 203.7(2) pm within the chain indicates the presence of quadruply bonded, diamagnetic (Cr(2))(4+) dimers and paramagnetic, pseudo-octahedrally coordinated Ni(2+) ions. This is in good agreement with the paramagnetic behavior found between 2 and 300 K, which can be described using the Curie-Weiss law. The obtained effective magnetic moment mu(eff) of 3.45 mu(B) clearly shows the existence of pseudo-octahedrally coordinated Ni(2+) (S = 1).
