The Solid-State Structures of Cyclic NH Carboximides

Abstract

The patterns adopted in the solid state structures of over 300 cyclic NH carboximides as determined by X-ray diffraction are reviewed. While the analysis shows that the majority of these fit into just a few common patterns, a significant number exhibit more complex and interesting patterns involving the other functional groups present in addition to the cyclic imide.

2,6-exo-8,10-exo-4-Butyl-9-oxa-4-azatetracyclo[5.3.1.02,6.08,10]undecane-3,5-dione

“…Molbank 2022, 2017, x FOR PEER REVIEW Although cyclic NH imides show a wide variety of intermolecular hydrogen bon patterns in the crystalline state [21], this relies on having a free NH present and, as m be expected, there are no strong intermolecular interactions between molecules of 3 in crystal. A view of the unit cell does however show the molecules arranged with hy phobic butyl groups in a layer between the more polar epoxy imide moieties (Figure In summary, the epoxy imide 3 is readily formed by spontaneous air oxidation o corresponding unsaturated imide 2 and preparation of the related epoxy anhydride lowed unambiguous assignment of 1 H and 13 C-NMR spectra for all three compounds.…”

“…The starting exo-anhydride 1 was prepare thermal isomerisation of the endo-isomer as described in the literature [9], with the tinction that acetone [2] rather than benzene was used for the recrystallisation. Although cyclic NH imides show a wide variety of intermolecular hydrogen bonding patterns in the crystalline state [21], this relies on having a free NH present and, as might be expected, there are no strong intermolecular interactions between molecules of 3 in the crystal. A view of the unit cell does however show the molecules arranged with hydrophobic butyl groups in a layer between the more polar epoxy imide moieties (Figure 4).…”

Solid State Structure and Hydrogen Bonding of Some Cyclic NH Carboximides

“…The Diels-Alder reaction of maleimide has been well investigated and at least 50 previous bicyclo[2.2.1] and [2.2.2] adducts derived in this way have been crystallographically characterised [1]. However, it is notable that these do not include many of the very simplest examples, such as the endo cyclopentadiene adduct 2 first reported as early as 1944 [20].…”

“…In our review [1], fifty Diels-Alder derived tricyclic succinimides were covered and fifteen of these show the centrosymmetric R 2 2 (8) dimer structure A while twenty show the linear C(4) ribbon structure B. The factors that favour one of these as opposed to the other are subtle and there seems to be a fine balance.…”

“…In a recent review in this journal [1] we surveyed the published crystal structures of over 300 cyclic NH carboximides containing the CO-NH-CO functional group and this revealed some important trends. In particular, two hydrogen bonded structures, namely, a centrosymmetric dimer A and a linear ribbon structure B involving two parallel rows of molecules exemplified for a simple monosubstituted succinimide (Figure 1) were by far the most common, accounting respectively for 119 and 74 examples among the total of 311 analysed.…”