Avogadro 1.2 has interfaces to a wide range of QM programs, including MOPAC, Gaussian, Orca, etc. (e.g., Extensions ⇒… pick your QM program of interest).
Avogadro 1.98 and later also have the same input generators to run calculations, but also have a new framework to enable calculations and optimizations with other programs (e.g., ML potentials like ANI-1x or GFN-FF / GFN-2, etc.)
My suggestion is to run a calculation. Orca, for example, is free for academic / personal use and B97-3c is a fast DFT method. (Actually, many methods will be fast on molecules this small.)
Another good package would be xtb which offers GFN-FF / GFN2 and is very fast.
Of course if you want heats of formation or \Delta G values, you’ll need to do a bit more work, but the results will be significantly more accurate than a force field.