The known, green, five-coordinate species trans-RuCl2(P-N)(PPh3) react with R'SH thiols to give yellow cis-RuCl2(P-N)(PPh3)(R'SH) products (P-N = o-diphenylphosphino-N,N'-dimethylaniline; R' = alkyl). The MeSH and EtSH compounds are structurally characterized, with the former being the first reported for a transition metal MeSH complex, while the thiol complexes with R' = Pr-n, Pr-i, (n)Pn (pentyl), (n)Hx (hexyl), and Bn (benzyl) are synthesized in situ. Other trans-RuX2(P-N) (PR3) complexes (X = Br, I; R = Ph, p-tolyl) are synthesized, and their H2S adducts, of a type reported earlier by our group, are also prepared. Thermodynamic data are presented for the reversible formation of the MeSH and EtSH complexes and the H2S analogues. The (RuCl2)-Cl-II(P-N)(PPh3) complex in solution decomposes under O-2 to form [(RuCl)-Cl-III(P-N)](2)(mu-O)(mu-Cl)(2).