title: The microwave and millimeter spectrum of ZnCCH (X̃2Σ+): a new zinc-containing free radical.
abstract: The pure rotational spectrum of the ZnCCH (X̃(2)Σ(+)) radical has been measured using Fourier transform microwave (FTMW) and millimeter direct-absorption methods in the frequency range of 7-260 GHz. This work is the first study of ZnCCH by any type of spectroscopic technique. In the FTMW system, the radical was synthesized in a mixture of zinc vapor and 0.05% acetylene in argon, using a discharge assisted laser ablation source. In the millimeter-wave spectrometer, the molecule was created from the reaction of zinc vapor, produced in a Broida-type oven, with pure acetylene in a dc discharge. Thirteen rotational transitions were recorded for the main species, (64)ZnCCH, and between 4 and 10 for the (66)ZnCCH, (68)ZnCCH, (64)ZnCCD, and (64)Zn(13)C(13)CH isotopologues. The fine structure doublets were observed in all the data, and in the FTMW spectra, hydrogen, deuterium, and carbon-13 hyperfine splittings were resolved. The data have been analyzed with a (2)Σ Hamiltonian, and rotational, spin-rotation, and H, D, and (13)C hyperfine parameters have been established for this radical. From the rotational constants, an r(m) ((1)) structure was determined with r(Zn-C) = 1.9083 Å, r(C-C) = 1.2313 Å, and r(C-H) = 1.0508 Å. The geometry suggests that ZnCCH is primarily a covalent species with the zinc atom singly bonded to the C≡C-H moiety. This result is consistent with the hyperfine parameters, which suggest that the unpaired electron is localized on the zinc nucleus. The spin-rotation constant indicates that an excited (2)Π state may exist ∼19,000 cm(-1) in energy above the ground state.
authors: Department of Chemistry and Biochemistry, 933 North Cherry Avenue, University of Arizona, Tucson, Arizona 85721, USA.
authors: J
authors: J
authors: Min
authors: D T
authors: DT
authors: Halfen
authors: M
authors: M
authors: Sun
authors: B
authors: B
authors: Harris
authors: L M
authors: LM
authors: Ziurys
mesh_terms: D005609:Free Radicals / Q000737:chemistry*; D008872:Microwaves; D013057:Spectrum Analysis / Q000379:methods*; D015032:Zinc / Q000737:chemistry*
chemical_list: D005609:Free Radicals; D015032:Zinc