ChemInform Abstract: MICROWAVE SPECTRA OF ((15)N) AND ((13)C) PYRIDINES, QUADRUPOLE COUPLING CONSTANTS, DIPOLE MOMENT AND MOLECULAR STRUCTURE OF PYRIDINE

Semi-Experimental Equilibrium Structure Determinations by Employing B3LYP/SNSD Anharmonic Force Fields: Validation and Application to Semirigid Organic Molecules

“…From Table 4, we note a significant decrease of the C3−C4 bond length when moving from furan to maleic anhydride (1.4344 Å in furan with respect to r(C1−C2) = 1.3320 Å in maleic anhydride, see Figure 1d) and a simultaneous increase of the C2−C3 bond length (1.3542 Å in furan with respect to 1.4857 Å in maleic anhydride), and of the ring C−O distance (from 1.3598 Å in furan to 1.3848 Å in maleic anhydride). Thanks to the large number of isotopologues experimentally investigated 116,117 (see Table 2 in the Supporting Information) and to the limited number of independent geometrical parameters (10), it is possible to determine a full SE equilibrium structure for pyridine (C 2v symmetry). The r e SE structure given in Table 5 has been obtained by fitting the SE I e A and I e C moments of inertia derived from the experimental rotational constants corrected by ΔB vib β contributions calculated at the B3LYP/SNSD level.…”