Rotational spectra of twenty-one vibrational states of [35Cl]-and [37Cl]-chlorobenzene.

[Display omitted] • Rotational spectrum (130–360 GHz) measured for chlorobenzene. • Constants determined for ground vibrational states of [35Cl]-, [37Cl]-chlorobenzene. • Constants determined for 7 fundamental states, 8 overtone/combination states of [35Cl]-chlorobenzene. • Constants determined for 4 fundamental states of [37Cl]-chlorobenzene. • Data enable detailed comparisons of spectroscopic constants with structurally related compounds. The rotational spectra of [35Cl]- and [37Cl]-chlorobenzene (C 6 H 5 Cl) have been studied from 2 to 18 GHz and 130–360 GHz, resulting in the measurement, assignment, and least-squares fitting of almost 40,000 transitions of twenty-one vibrational states. Previously measured [35Cl]- and [37Cl]-chlorobenzene ground-state transitions were combined with newly measured transitions and fit to A-reduced, partial sextic Hamiltonian models with low-error (σ total fit <0.05 MHz). Analysis of the 2–18 GHz spectrum allowed for refinement of the nuclear hyperfine coupling constants for the ground-state spectra of both isotopologues, while measurement of the 130–360 GHz spectrum provided sufficient information to determine the sextic centrifugal distortion constants of the ground states for the first time. From these millimeter-wave data collected at room temperature, the spectroscopic constants for the lowest-energy fundamentals of [35Cl]-chlorobenzene (ν 20 , ν 30 , ν 11 , ν 14 , ν 19 , ν 29 and ν 18) and [37Cl]-chlorobenzene (ν 20 , ν 30 , ν 11) were determined. As with previous studies of chloroarenes, the computed (B3LYP/6–311+G(2d,p)) spectroscopic constants show quite close agreement with the experimentally determined values. [ABSTRACT FROM AUTHOR]