Microwave spectra of isotopic benzonitriles. Refined molecular structure of benzonitrile

1,2-Dicyanobenzene. A Precursor of Phthalocyanines

“…The mean aromatic C---C bond length of 1.377/~ is comparable to analo~gous mean distances found in the 1,4-isomer (1.388A; Driick & Littke, 1978) and in 1,2,4,5-tetracyanobenzene [1.401 (8)/~; Prout & Tickle, 1978]. The ~N bond length of 1.149 (8)/~ is typical of cyano groups and comparable to C--N distances found in various cyano derivatives (Britton, 1981a, b;Casado, Nygaard & Sorensen, 1971;Colapietro, Domenicano, Marciante & Portalone, 1981). The C---CN distance of 1.430 (7).…”

Coupled electron pair calculations for R-C  E molecules (E = N, P, As or Sb)

“…zonitrile [47]. It is plausible that the electronic structure and the geometric parameters of the C-C=E fragment (C = ipso carbon atom) are only weakly influenced by the accurate ring geometry.…”

“…It is plausible that the electronic structure and the geometric parameters of the C-C=E fragment (C = ipso carbon atom) are only weakly influenced by the accurate ring geometry. Alterations of the ring (compared with benzene) affect mainly the angle E (C2-C-C6) and the bond length a (C-C2; C-C6), and are relatively small: (i) The measured ring geometries of benzonitrile (H,C, -C=N) [47,48] and of ethynylbenzene (H,C,-CCC-H) [49] deviate from those of benzene by less than 0.01 A or 2'.…”

“…Casado et al [47] claim the r, structure to be "still the best estimate of the equilibrium structure of benzonitrile". However, the paper also determines an average structure with r, = 1.444 A for the C-C bond in question.…”

“…Some ambiguity exists about the C-C( =N) bond length in benzonitrile. Using microwave spectroscopy and isotopic substitution, Casado et al [47] (cf. ref.…”