The crystal and molecular structures of the title compounds are described. Both contain a triangular Ru3 core [average Ru-Ru 2·853 (n = 1), 2·837 Å (n = 2)], with the PMe3 ligands occupying equatorial positions. For n = 2, substantial twisting about the Ru-Ru bonds results in one CO group adopting a semibridging position across the Ru-Ru vector joining a substituted Ru with the Ru(CO)4 fragment. Comparisons are also made with the previously determined n = 3 complex.