
%0 Journal Article
%A Appleton, TG 
%A Gahan, LR 
%A Oliver, PJ 
%T Isolation, X-Ray Crystal Structure and <sup>59</sup>Co Nuclear Magnetic Resonance Spectral Investigation of the Partially Nitrated Cobalt(III) Acetylacetonato Complex [Co(acac)<sub>2</sub>(NO<sub>2</sub>acac)]
%J Australian Journal of Chemistry
%D 1992/05/01
%V 45
%N 5
%P 797-805
%K 
%R https://doi.org/10.1071/CH9920797
%U https://www.publish.csiro.au/paper/CH9920797 
%X The complex [Co( acac )2(NO2acac)] has been isolated after fractional crystallization from a reaction mixture of [Co( acac )3] and nitrating agent. The complex crystallizes in the triclinic space group P1, with c 14.557(2) Å , &#945; 78.98(1), &#946; 83.71(2), &#947;75.32(1)&#176; and Z 2. The structure refined to a final R value of 0.074 for 2287 'observed' [I > 3 &#963;(I)] reflections. The structure consists of discrete complex molecules with the cobalt atom surrounded by six oxygen atoms at the corners of a distorted octahedron. The NO2 group is twisted at 50.7º to the chelate ring on which it is situated and has little influence on the geometry, with intrachelate and interchelate oxygen-oxygen separations essentially the same as those found in [Co( acac )3]. The 59Co n.m.r. spectra of the [Co( acac )2(NO2acac)] complex, as well as [Co( acac )3], [Co(NO2acac)3] and [Co( acac )(NO2acac)2], have been recorded, this resonance being particularly sensitive to substitution on they &#947;carbon atom of the acetylacetonato chelate ring. The 59CO relaxation rates for the [Co( acac )2(NO2acac)] and [Co( acac )(NO2acac)2] complexes are faster than that displayed by the symmetric [Co(NO2acac)3] complex, (1948 ± 20, 2765 ± 30 and 1696 ± 20 s-1, respectively). The results obtained for the relaxation rates for these complexes are compared with those obtained for similar halide-substituted complexes [Co( acac )3-n( Xacac )n]   (X = Cl , Br, I; n = 0-3). 
