The Fourier transform microwave spectrum of YC2 (X˜2A1) and its 13C isotopologues: Chemical insight into metal dicarbides

► The pure rotational spectrum of YC2 measured using FTMW methods from 10 to 57 GHz. ► An accurate structure for YC2 was determined from measurements of 3 isotopologues. ► Structure shows covalent character with an activated C-C bond. ► Hyperfine terms show that the unpaired electron is in a sd-hybridized orbital on Y.