Structure of the (2-acetamidobenzoyl)formate anion as the benzamidinium salt

Abstract

The reaction of isatin with benzamidine hydrochloride in methanol yields the title compound, benzamidium (2-acetamidobenzoyl)formate (C7H 9-N~.CmHsNO4). In the benzamidinium cation the configuration about the exocyclic C atoms is planar, resulting in electron delocalization in the C--N bonds. The C--O bond distances in the carboxylate © 1994 International Union of Crystallography Printed in Great Britain -all rights reservedThe IR spectrum (KBr pellet) of the compound showed the following absorptions: 3400-3240 (broad, NH, NH2), 1700 (CO), 1450 (C--N), 1320 (C~N) cm-1. The following IH NMR parameters confirm the structure of the compound: & 2.18 (s, 3H, CH3) , 3.48 (broad, 4H, NH2), 9H, Ar), 11.88 (s, 1H, NH). The mass spectrum showed the molecular ion peak at m/z 327 (M÷).The title compound (I) is composed of two parts: the benzamidinium cation and the (2-acetamidobenzoyl)formate anion. The formation of this salt appears to occur through a ring-opening reaction in which a C--N bond of isatin is cleaved, followed by the addition of a water molecules resulting in the formation of (II) (an intermediate under these conditions), then a simple acid-base reaction of (II) with benzamidine rather than a Schiff base condensation.[~, OK_~ OH-p COCH 3" 00Acta Crystallographica Section C ISSN 0108-2701 ©1994 K. C. JOSHI, R. BOHRA, R. JAIN AND S. ARORA 1793The benzamidinium cation has the expected structure. The rr electrons are delocalized over the C(7), N(1) and N(2) atoms, which is evident from the average C--N distance of 1.309 (7)A, indicating considerable double-bond character. The sums of the bond angles about C(7), N(1) and N(2) are 359.9(14), 360.6(10) and 360(13) °, respectively. These data indicate the essentially planar hybridization about these atoms. The distance between C(1) and C(7) [1.479 (7) A,] represents a normal C~p2--Csp2 single bond.The average value of the C(15)--0(2) and C(15)--0(4) bond distances in the anion is 1.238 (6)A, indicating that the negative charge is delocalized over these atoms. The N(3)--H3n bond length is 1.13 (8) A indicating normal single-bond character. The dihedral angle between the plane defined by C(14), O(1), C(15) and C(13) and that defined by C(8), C(9), C(10), C(I1) and C(12) is 7.33_ 1.19 °, which is a measure of the non-coplanarity of the phenyl ring of the indole and the carbonyl groups. The dihedral angle between the plane defined by C(7), N(1), N(2) and H lna and H lnb and that defined by C(1), C(2), C(3), C(4), C(5) and C (6) ExperimentalA mixture of N-acetyl isatin (0.01 mol), benzamidine hydrochloride (0.01 tool) and K2CO3 (1 g) was refluxed in methanol (50 ml) for 3 h. A white product was obtained on cooling, which was then recrystallized from methanol (yield 2.25 g, 69%); m.p. 469 K. Analysis: calculated for N(1)--C (7) 1.289 (7) O(4)---42 (15) 1.222 (6) N(2)---C (7) 1.329 (7) N(3)---C(12) 1.379 (7)1.380 (7) C (9) (7) 121.4 (5) N(3)--C(12)--<2(13) 117.6 (5) C(6)--C(1)--C (7) 119.5 (5) The data were corrected for Lorentz and polarization effects. There...

Benzamidinium acetylsalicylate: crystal structure of the first salt with acetylsalicylate anion

“…15. (2) to 2.871(2) Å and leading to an infinite chain structure similar as in the structure of the known compound benzamidinium (2-acetamidobenzoylformate) [8] (Fig. 3).…”

“…We were able to isolate the acetylsalicylate anion in the presence of the benzamidinium cation. The protonated analog of benzamidine is a multiple hydrogen bonding donor and its amdidinium group exhibits ideal requirements to form dimers with carboxylate groups in the solid state via N-HÁÁÁO hydrogen bonds [6][7][8]. The parent compound benzamidine has also biological and pharmacological relevance.…”

Supramolecular association in proton-transfer adducts containing benzamidinium cations. III. Three molecular salts of 3-methoxy-, 4-methoxy- and 3,4,5-trimethoxybenzoates with benzamidine

“…In the cationic substructures, where protonation takes place at the same site of the amidine group, the benzamH + cations are not planar. The dihedral angles between the mean plane of the benzene ring and the amidinium group are in the range 30.7 (1)-42.3 (1) , larger than the values observed in benzamidinium (2-acetamidobenzoyl)formate [16 (3) ; Joshi et al, 1994], benzamidinium acetylsalicylate [15.2 (2) ; Kolev et al, 2009] or the two polymorphic forms of benzamidinium 2,6dimethoxybenzoate [20.2 (1), 14.4 (1) and 23.6 (1) ; Irrera et al, 2012]. For all compounds, this disposition is a consequence of the steric hindrance between the NH 2 group and the benzene ring, as indicated by the N-C(ortho) contacts which are in the range 2.888 (2)-2.969 (2) Å , and it prevents conjugation between the amidinium group and the benzene ring.…”

Supramolecular aggregation by means of charge-assisted hydrogen bonds in acid-base adducts containing amidinium cations

“…This pattern is reproduced in all the four cases, irrespective of the cation dimension (the R substituent of Scheme 1 varies from a methyl to a butyl group), and seems to be peculiar for the nitrate/amidinium couple. In only two structures, molecules are assembled into infinite ribbons (for example the packing of HEVSAC 18 in Fig. 7), while the remaining structures show packing patterns constituted by three dimensional H-bond networks, very difficult to predict ' a priori '.…”