Structure of 4-carboxy-2-nitrobenzeneboronic acid

Abstract

4-(Dihydroxyboryl)-3-nitrobenzoic acid, C7H6BNO6, M(r) = 210.94, monoclinic, P2(1)/n, a = 10.542 (2), b = 6.411 (1), c = 13.105 (4) A, beta = 106.47 (2) degrees, V = 849.3 (4) A3, Z = 4, Dm = 1.65 (flotation in CCl4/1,2-dibromoethane), Dx = 1.649 Mg m-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.135 mm-1, F(000) = 432, T = 293 K, R = 0.0530 for 1328 observed reflections with F > 2 sigma(F). The molecule is flat [the carboxy and nitro groups are rotated 5.8 (4) and 1.9 (4) degrees, respectively, out of the plane] with the boronic acid group almost normal to the plane of the benzene ring, 92.4 (3) degrees. The B atom and one O atom of the nitro group are separated by only 2.457 (4) A implying an interaction that is consistent with observed chemical behavior.

Monosubstituted Phenylboronic Acids, R–B(OH)2 (R = C6H5, C6H4CH3, C6H4NH2, C6H4OH, and C6H4F): A Computational Investigation

“…Similar twists have also been observed in the crystal structures of several substituted PBA dimers [28, 53, 70], suggesting a relatively flat rotational potential energy curve around the C–B bond. Indeed, the calculated the values of ΔH † for internal rotation about the C–B bond for the endo-exo , anti , and syn conformers of the PBA monomer in the gas phase are only 3.0 kcal/mol, 1.3 kcal/mol, and 4.8 kcal/mol respectively at the MP2/aug-cc-pVDZ level.…”

4-(Acetylamino)-3-hydroxy-5-nitrobenzoic Acid

“…CO2H, NO2, OH and C2HnNO, are also listed in Table 2. The crystal structure of the title compound is similar to other phenyl-ring-based structures (Bryan, Hartley, Peckler, Fujita, Nagao & Seno, 1980;Bums & Hagaman, 1993;Carpy, Goursolle & Leger, 1980;Gozlan & Riche, 1976;Kageyama, Iwamoto, Haisa & Kashino, 1993;Metzger, Laidlaw, Torres & Panetta, 1989;Metzger, Atwood, Lee, Rao, Lal & Loo, 1993;Nielsen & Larsen, 1993;Okabe, 1993;Okabe, Nakamura & Fukuda, 1993;Soundararajan, Duesler & Hageman, 1993). …”

A Computational Investigation of the Geometrical Structure and Protodeboronation of Boroglycine, H2N−CH2−B(OH)2

“…The calculated B-C distance in 1a, ∼1.59 Å, is in good agreement with the observed B-C distance of 1.588 Å in the crystal structure of 2-nitro-4-carboxyphenyl boronic acid; the -B(OH) 2 moiety in this crystal structure was nearly perpendicular to the phenyl ring, which minimized the bond-shortening effects of conjugation. 1,96 Geometrical structures of several additional local minima on the H 2 N-CH 2 -B(OH) 2 PES are also shown in Figure 1A; they are all higher in energy (see Table 1A). For comparison, we note that the anti form, 2a, is less than 3 kcal/mol higher in energy than 1a, whereas the syn form, 3a, is greater than 6 kcal/ mol higher in energy.…”