Synthese und Eigenschaften von Pentaazadienido-Komplexen des zweiwertigen Cobalts. Kristallstruktur von [Co(OCH3)(tolNNNNNtol)]6 · 2C9H12

Abstract

Abstract Co(tolNNNNNtol)2 (1) is obtained from solutions of 1,5-di-p-tolyl-1,4-pentaazadiene und CoCl2 - 6H2O in aqueous ammonia. It is a paramagnetic, explosive, red com pound which reacts with alcohols to the alcoholates Co(OR)(tolNNNNNtol). The methoxy complex is hexameric. It crystallizes from mesitylene/methanol as [Co(OCH3)(tolNNNNNtol)]6 · 2C9H12 in the triclinic space group P1̄ with the lattice constants: a = 1667.1(5), b - 1784.2(5), c = 2159.2(6) pm, α = 93.05(3)°, β = 96.10(2)°, γ = 64.63(2)°, Z = 2. In the hexameric complex six Co atoms and six methoxy groups form a central twelve membered Co - O ring with a symmetry close to D3d. The pentaazadienide ligands act as additional bridges between two Co atoms, coordinating one Co atom monodentate with N1 and the other Co atom bidentate with N3 and N5. This leads to alternating tetrahedral and octahedral coordination of the Co atoms. The average Co-O distances are 192,3 pm in the CoO2N2 tetrahedron and 198,0 pm in the CoO2N4 octahedron. The corresponding Co-N distances are 206.3 and 221.4 pm respectively. In the planar N5 zigzag chain slightly elongated double bonds N1 - N2 and N4 -N5 of 128.2 pm and partial double bonds N2 -N3 and N3 -N4 of approximately 134.6 pm are observed.