6533b7d7fe1ef96bd12682d2

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Study of the mutual influence of ligands in cobalt(II) complexes containing thiocyanate and imidazole derivatives

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Abstract The cobalt(II) complexes of formula [Co(NCS)2L2] and [Co(NCS)2L′4] (L = imidazole (iz) derivatives, I-Meiz (1), Z-Meiz (2), 2-Etiz (3), 2-Isopropiz (4), 2-Pheniz (5), 1,2-Me2iz (6), Biz (7), 2-Mebiz (8), 2-Etbiz (9); L′ = iz (10), 1-Meiz (11)) have been synthesized and characterized by spectroscopic methods and magnetic measurements. The crystal and molecular structures of complexes 6 and 11 have been determined by X-ray diffraction methods. Complex 6 crystallizes inthe orthorhombic space group Pnma with cell constants a=9.209 (3), b = 12.462 (5), c = 14.851(3) A ; V = 1704.3(9) A 3 , D ( calc ., Z = 4) = 1.43 g cm −3 , M r =367.35, F(000)=640 , λ( Mo K α)=0.71079 A , μ=11.2 cm−1 and T=293 K. Complex 11 crystalizes in the monoclinic space group P21/nwith cell constants a=7.689(2), b=11.095(1), c=14.156(2) A , β=93.46(2)°; V=1205.4(3) A 3 , D ( calc ., Z=2)=1.39 g cm −3 , M r =503.51, F(000)=534, λ( Mo K α)=0.71079 A , μ=8.56 cm−1 and T=293 K. 2553 (6) and 2485 (12)reflections were collected over the range 1≤θ≤25; from these, 1571 (6) and 1977 (11) (independent with I≥3σ(I)) were used in the structural analysis. The final value of the Rw residual was 0.077 and 0.042 for (6) and 11, respectively. The structure of 6 is built up by [Co(NCS)2(1,2-Me2iz)2] mononuclear units where the metal atom exhibits an approximately tetrahedral configuration: the CoN bond distances and NCoN bond angles vary in the range 1.958(8)−1.922(8) A and 114.7(3)−108.3(3)°, respectively. The structure of 11 consists of [Co(NCS)2(1-Meiz)4] monomeric units where two N-coordinated thiocyanate groups in trans position and four 1-methylimidazole ligands build a slightly distorted CoN6 octahedral environment. The CoN bond lengths lie i the range 2.158(2)–2.135(3) A being significantly longer than the related ones observed in 6.