Coordinatively unsaturated rhodium and iridium complexes bearing a bulky thiolate ligand, [Cp*M(SDmp)](BAr ) (2a, M = Rh; 2b, M = Ir; Cp* = ? -C Me ; Dmp = 2,6-(mesityl) C H ; Ar = 3,5-(CF ) C H ) were synthesized from the reactions of [Cp*MCl] (μ-Cl) with LiSDmp and NaBAr . The metal centers in 2a and 2b weakly interact with the ipso-carbon of one of the mesityl groups in the SDmp ligand, while the ipso-carbon dissociates from the coordination sphere in the reactions with donor ligands. Treatment of 2a or 2b with 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) led to the formation of [Cp*M(SDmp)(bpy)] (BAr ) (3a, M = Rh; 3b, M = Ir) or [Cp*M(SDmp) (phen)](BAr ) (4a, M = Rh; 4b, M = Ir), respectively. The reactions of 2a and 2b with 2 equiv of tert-butylisocianide or 1 atm of CO gave rise to the bis-adducts [Cp*M(SDmp)(L) ](BAr ) (5a, M = Rh, L = CN Bu; 5b, M = Ir, L = CN Bu; 6a, M = Rh, L = CO; 6b, M = Ir, L = CO). The coupling of terminal alkynes and SDmp took place upon the addition of excess 1-pentyne or phenylacetylene to solutions of 2a or 2b, affording cationic complexes with an S-arylated thiophene group, [Cp*M(? -2, 4-R C H S-Dmp)](BAr ) (7a, M = Rh, R = Pr; 7b, M = Ir, R = Pr; 7c, M = Rh, R = Ph; 7d, M = Ir, R = Ph). © 2010 American Chemical Society. F 5 F F F F F t t 4 F n n 4 5 5 2 6 3 3 2 6 3 2 2 4 4 4 2 4 2 4 2 4