## Abstract

The rotationally resolved infrared spectrum of the B-D _{2} ion-neutral complex is recorded in the D-D stretch vibration region (2805-2875 cm ^{-1}) by detecting B photofragments. Analysis of the spectrum confirms a T-shaped equilibrium geometry for the B-D _{2} complex with a vibrationally averaged intermolecular bond length of 2.247 Å, around 0.02 Å shorter than for the previously characterised B-H _{2} complex [V. Dryza, B. L. J. Poad, and E. J. Bieske, J. Am. Chem. Soc. 130, 12986 (2008)10.1021/ja8018302]. The D-D stretch band centre occurs at 2839.76 ± 0.10 cm ^{-1}, representing a -153.8 cm ^{-1} shift from the Q _{1}(0) transition of the free D _{2} molecule. A new three dimensional ab initio potential energy surface for the BH _{2} interaction is calculated using the coupled cluster RCCSD(T) method and is used in variational calculations for the rovibrational energies of B-H _{2} and B-D _{2}. The calculations predict dissociation energies of 1254 cm ^{-1} for B-H _{2} with respect to the BH _{2} (j = 0) limit, and 1313 cm ^{-1} for B-D _{2} with respect to the BD _{2} (j = 0) limit. The theoretical approach reproduces the rotational and centrifugal constants of the B-H _{2} and B-D _{2} complexes to within 3, and the magnitude of the contraction of the intermolecular bond accompanying excitation of the H _{2} or D _{2} sub-unit, but underestimates the H-H and D-D vibrational band shifts by 7-8. Combining the theoretical and experimental results allows a new, more accurate estimation for the B-H _{2} band origin (3939.64 ± 0.10 cm ^{-1}).

Original language | English |
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Article number | 124312 |

Journal | Journal of Chemical Physics |

Volume | 137 |

Issue number | 12 |

DOIs | |

Publication status | Published - 28 Sep 2012 |

Externally published | Yes |

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