The Fourier transform microwave spectrum of YC2 ((X) over tilde (2)A(1)) and its C-13 isotopologues has been measured in the 10-57 GHz range, the first FTMW study of a metal dicarbide species. The molecule was created from yttrium vapor and CH4 in argon in a supersonic jet with a discharge-assisted laser ablation source (DALAS). Rotational, fine structure, and Y and C-13 hyperfine constants were determined for each isotopologue. The calculated r(m)((1)) structure is r(Y-C) = 2.187(4) angstrom, r(C-C) = 1.270(4) angstrom, and theta(C-Y-C) = 33.74(7)degrees. The hyperfine parameters indicate that the unpaired electron resides principally in an sd hybridized orbital on the yttrium nucleus. (C) 2012 Elsevier B. V. All rights reserved.