Structural studies of linear molecules by microwave spectroscopy

Abstract

Rotational constants have been measured for three isotopic forms of fluorine cyanide, six isotopic forms of fluoroacetylene, and for the species 35ClC15N, 37ClC15N, IClsN, 35C113CCH and 35ClC13CH. Accurate bond-distances have been computed for all the halogen cyanides and for fluoro-and chloroacetylene, by the method of isotopic substitution at all atoms (except I; and I). The CF bonds in these compounds are the shortest yet found. The CN distance is virtually constant at 1.159 A.The nuclear quadrupole coupling constant for nitrogen-14 in fluorine cyanide, -2.67 Mc/sec, is the lowest yet measured for a cyanide grouping. The dipole moments of fluorine cyanide and fluoroacetylene, from Stark effects, are 217 D and 0.73 D respectively. Rotation spectra of molecules in excited bending vibrational states are analyzed for fluorine cyanide, fluoroacetylene and cyanoacetylene.

Ab Initio Calculation of Molecular Properties of Cyanopolyynes, H—(C≡C)n—CN

“…For example, the calculated dipole moments of 3.042, 3.874, 4.474 Debye for HCN, HC3N and HC5N, respectively agree fairly well with experimental values of 2.99 [3], 3.6 [5] and 4.33 [3]. The calculated dipole moments from the 6-31G** basis set for HCN and HC3N are shown to overestimate the corresponding experimental values.…”

“…Previously, lower members of cyanopolyynes also have been detected partly from the chemical preparation of these compounds in the laboratory or partly from the interstellar space; HC3N [2][3][4], HC5N [5][6][7], HC7N [8,9] and HC9N [10,11].…”

A theoretical study of adiabatic proton transfer to simple substituted acetylenes In Their Ground And Excited States

“…The 3-21G predicted structural parameters for the ground states of Y-C=C-H (Y = F, C1, CH3, CF3) are given in Table 1 and can be seen to agree quite well with their experimentally determined counterparts (12)(13)(14)(15), with the exception of r(C1-C), as expected (16).…”

Ab initio determination of the electric multipole moments and static (hyper)polarizability of HCCX, X = F, Cl, Br, and I

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] As a result, experimental values of the dipole moment have been reported for all monohaloethynes. 2,7,8,10,11,12,14 The quadrupole moment has been measured for HCCF, 4 HCCCI, 5 and HCCBr. 6 Experimental data are also available for the anisotropy of the dipole polarizability of HCCCl 10 and HCCI.…”