Isolation, X-Ray Crystal Structure and 59Co Nuclear Magnetic Resonance Spectral Investigation of the Partially Nitrated Cobalt(III) Acetylacetonato Complex [Co(acac)2(NO2acac)]

Abstract

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) � , α 78.98(1), β 83.71(2), γ75.32(1)° and Z 2. The structure refined to a final R value of 0.074 for 2287 'observed' [I > 3 σ(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 50.7� 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 γcarbon 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).

Tris(3-nitropentane-2,4-dionato-κ2O,O′)cobalt(III)

“…1), forming angles of 49.3 (1), 59.3 (2), and 50.3 (2) degrees for the major components and 67.2 (2) and 51.6 (8) degrees for the minor disorder components. These are similar to the angle of 50.7 degrees observed for the mono-nitro cobalt complex (Appleton et al, 1992). The disorder in the positioning of one chelate ring has been observed previously (as large thermal parameters) for analogous complexes of cobalt and manganese (Appleton et al, 1992).…”

“…These are similar to the angle of 50.7 degrees observed for the mono-nitro cobalt complex (Appleton et al, 1992). The disorder in the positioning of one chelate ring has been observed previously (as large thermal parameters) for analogous complexes of cobalt and manganese (Appleton et al, 1992). Chrzanowski et al, 2007).…”

“…For spectroscopic properties of the title compound, see: Singh & Sahai (1967, 1968; Larsson & Eskilsson (1969); Fleming & Thorton (1973, 1975; Tsiamis et al (1987). For crystallographic studies of related compounds, see: Appleton et al (1992); Abrahams et al (1998); Tsiamis et al (1998); von Chrzanowski et al (2007). For a review of graph-set analysis of hydrogen-bonding patterns, see: Bernstein et al (1995).…”

Crystal structures of chloro-, bromo-, and nitro-substituted chromium(III) acetylacetonates

“…There are data reported in literature about structures of substituted bisacetylacetonates, e.g. Cu(acacCl) 2 [13], Cu(acacNO 2 ) 2 [14], not fully substituted chelates ((Hacac) 2 Ru(acacS)) 2 [15], Co(acac) 2 (acacNO 2 ) [16], and complexes, containing not only diketonate ligands ((MeO)Cr(acacBr) 2 ) 2 [17].…”