Structural studies of peri-interactions and bond formation between electron-rich atomic centres and N-phenylcarboxamides or nitroalkenyl groups

Structural studies of peri-interactions with dimethylamino groups in naphthalene systems indicate that the N-phenylcarboxamide group has a through-space electron attracting power closer to that of a carboxylic ester than a N,N-dialkylcarboxamide, while 2-nitroalkenyl groups have a lower through-space electron attracting power. However, addition of a benzoyl group to the 2-position of the nitroethenyl group leads to cyclisation to give a zwitterion, in which the carbanion is stabilised by full conjugation with the nitro group and partial conjugation with the carbonyl group. An interesting case where a steric interaction overrides an electrophile/nucleophile attraction is also described. The limitations to the interpretation of short contact distances from crystallographic measurements are discussed

Attractive interactions between functional groups in crowded molecules: The solid state structures of diethyl 2-cyano(2 '-nitrophenyl)methyltartronate and diethyl (2 '-,6 '-dinitrophenyl)methyltartronate

The molecular structures of two substituted diethyl tartronates show a variety of interactions between functional groups. Oxygen atoms interact with the electron deficient carbon and nitrogen atoms of nitrile and nitro groups which in response show small distortions from their normal geometries. Short O . . . H contacts between benzyl hydrogen atoms and ortho nitro groups indicate some weak hydrogen bonding effects. Crystal data: C15H16N2O7, Mr = 336.3, a = 7.668(2), b = 7.961(3), c = 15.244(3) Angstrom, alpha = 86.78(1), beta = 81.56(1), gamma = 61.92(1)degrees, triclinic, P (1) over bar, Z = 2; C14H16N2O9, MY = 356.3, a = 7.786(2), b = 10.324(2), c = 11.155(4) Angstrom, alpha = 71.43(2), beta = 77.21(2), gamma = 76.40(3)degrees, triclinic, P (1) over bar and Z = 2

Excess Volumes of 1,4-Dioxane + Ethane-1,2-diol at 298.15 K

Excess molar volumes of the 1,4-dioxane + ethane-1,2-diol liquid mixture were measured at 298K using a dilution dilatometer. The observed composition dependence does not confirm the W-shaped form as suggested by some other data published in the literature