The pure rotational spectrum of CuCCH in its ground electronic state (X̃ 1∑+) has been measured in the frequency range of 7-305 GHz using Fourier transform microwave (FTMW) and direct absorption millimeter/submillimeter methods. This work is the first spectroscopic study of CuCCH, a model system for copper acetylides. The molecule was synthesized using a new technique, discharge assisted laser ablation spectroscopy (DALAS). Four to five rotational transitions were measured for this species in six isotopologues (63CuCCH, 65CuCCH, 63Cu 13CCH, 63Cu 13CH, 63Cu 13CCH, and 63CuCCD); hyperfine interactions arising from the copper nucleus were resolved, as well as smaller splittings in CuCCD due to deuterium quadrupole coupling. Five rotational transitions were also recorded in the millimeter region for 63CuCCH and 65CuCCH, using a Broida oven source. The combined FTMW and millimeter spectra were analyzed with an effective Hamiltonian, and rotational, electric quadrupole (Cu and D) and copper nuclear spin-rotation constants were determined. From the rotational constants, an rm2 structure for CuCCH was established, with r Cu-C =1.8177 (6) Å, rC-C =1.2174 (6) Å, and rC-H =1.046 (2) Å. The geometry suggests that CuCCH is primarily a covalent species with the copper atom singly bonded to the CCH moiety. The copper quadrupole constant indicates that the bonding orbital of this atom may be sp hybridized. The DALAS technique promises to be fruitful in the study of other small, metal-containing molecules of chemical interest.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry