A determination of the electronegativity parameter in molecular orbital calculations on heteronuclear molecules containing nitrogen

Structure of 7-chloro-2,3-dihydro-1-methyl-5-phenyl-1H-1,4-benzodiazepine hydrochloride (medazepam hydrochloride)

“…The two measurements for this bond in medazepam base agree closely (1.493 and 1.498/k) so that this difference may well be real and related to the effect of protonation at the adjacent N atom. N(4)--C(5), 1.285 (4) /k, agrees to within the limits of experimental error with the accepted value of 1.274 /k (Lofthus, 1959) for a C-N double bond. In general, bond angles for the base and cation also agree closely.…”

Structures of the nitrosamides: (I) N-methyl-N-nitrosourea, (II) N,N'-dimethyl-N-nitrosourea, (III) 2-nitroso-2-azabicyclo[2.2.2]octan-3-one and (IV) N-methyl-N-nitroso-p-nitrobenzamide

“…There are no significant differences in dimensions between the cis and trans conformers other than those directly attributable to the constraints of the bicyclo[2.2.2]octane system. The relatively long C-N(NO) bonds in nitrosoureas and nitrosamides with conventionally determined (Lofthus, 1959) n bond orders of 0.2 and 0.3 suggest that the energy barriers between the cis and trans rotational conformers may be low. Consideration of the electrical dipolar value of the C=O and N--N(O)bonds points to the trans form as the more stable, that is the form found in (I), (II), (IV) and (VI) where there are no other constraints.…”

Structure of 4-bromo-1-(4-nitrophenyl)-3-phenylpyridazinium-5-olate, C16H10BrN3O3

“…The measured AR(CN) of 0.106 A in (IIa) [exceeding the limiting value of 0.06 ./k for azo-hydrazone forms (Kelemen et al, 1982)] is in accordance with the picture. On the basis of Lofthus's (1959) bond-order-bond-length relationships bond orders of 1.4 v.u. are derived for the NN bond and 1.6, 1.7 and 1.1 v.u.…”