## Abstract

A total of 60 a- and b-dipole rotational transitions were measured in the 4-18 GHz range for the NNO-HCN, ^{15}NNO-HCN, and NNO-DCN bimolecular complexes using a pulsed-beam, Fourier transform microwave spectrometer. Spectroscopic constants (A - D_{K}), B, C, D_{J}, D _{JK}, eQq_{aa} (N of HCN), and eQq_{bb} (N of HCN) were obtained by fitting the observed transition frequencies with a first-order quadrupole coupling interaction Hamiltonian. The structure of the complex appears to be planar with NNO and NCH nearly parallel. It can be described with the distance R_{cm} between the center-of-masses of the monomer subunits, the angle θ between HCN and R_{cm}, and the angle φ between N_{2}O and R_{cm}. A least-squares fit to the nine rotational constants to obtain the structure parameters R_{cm}, θ, and φ, produced three local minimia for bent structures with standard deviations of < 25 MHz. A Kraitchman analysis was used to determine magnitudes of principal axes coordinates for the N of HCN, and the terminal N of NNO. The best nonlinear least-squares fit result (structure I, lowest standard deviation of the fit = 7.2 MHz) produced the best match to the coordinates from the Kraitchman analysis. The spectroscopic constants B, C, and eQq_{aa} were used in a second structural analysis to determine values for R _{cm}, θ, and φ. These results were compared with the above coordinates. The best least-squares fit structure parameters for the vibrationally averaged structure are R_{cm} = 3.253(4) Å, θ = 89.1 (5.4)°, and φ = 76.4(0.4)°. Comparisons are made with other similar weakly bound complexes.

Original language | English (US) |
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Pages (from-to) | 3881-3886 |

Number of pages | 6 |

Journal | The Journal of Chemical Physics |

Volume | 93 |

Issue number | 6 |

DOIs | |

State | Published - Jan 1 1990 |

## ASJC Scopus subject areas

- Physics and Astronomy(all)
- Physical and Theoretical Chemistry