The ground-state rotational spectrum and molecular geometry of ethynylstannane

Abstract

The ground-state rotational spectra of 24 isotopomers of ethynylstannane have been observed by pulsed-jet, Fourier-transform microwave spectroscopy. The spectroscopic constants, B_0,D_J and D_JK are reported for symmetric-top isotopomers H₃ⁿSn¹²C¹²CH, where n = 116, 117, 118, 119, 120, 122 and 124, D₃ⁿSn¹²C¹²CH, where n = 116, 118, 120, 122 and 124, H₃ⁿSn¹³C¹² CH and H₃ⁿSn¹²C¹³CH , where n = 116,118 and 120, and H₃ⁿSn¹²C¹²CD, where n = 116, 118 and 120. In addition, the values of A₀, B₀, C₀, Δ_J and Δ_JK were obtained for the three asymmetric-top isotopomers DH₂ⁿSn¹²C¹²CH, where n = 116, 118 and 120. Hyperfine structure was resolved and assigned in the transitions of the isotopomers H₃ⁿSnCCD, where n = 116, 118 and 120, and in the isotopomers H₃¹¹⁷SnCCH and H₃¹¹⁹SnCCH. In the former group, the hyperfine structure arises from D nuclear quadrupole coupling while in the latter group its origin lies in the spin-rotation coupling of the I = 1/2 Sn nuclear spin to the rotational motion. For these isotopomers, D nuclear quadrupole and spin-rotation coupling constants are determined where appropriate. The rotational constants obtained for the 24 isotopomers of H₃SnCCH were used to obtain the following types of molecular geometry for ethynylstannane: r₀, r_s, and r_m.