Synthesis and Reactions of Coordinatively Unsaturated Half-Sandwich Rhodium and Iridium Complexes Having a 2,6-Dimesitylbenzenethiolate Ligand

Coordinatively unsaturated rhodium and iridium complexes bearing a bulky thiolate ligand, [Cp*M(SDmp)J(BAr4F) (2a, M = Rh; 2b, M = Ir; Cp* = eta(5)-C5Me5; Dmp = 2,6-(mesityl)(2)C6H3; Ar-F = 3,5-(CF3)(2)C6H3) were synthesized from the reactions of [Cp*MCl](2)(mu-Cl)(2) with LiSDmp and NaBAr4F. 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)](BAr4F) (3a, M = Rh; 3h, M = Ir) or [Cp*M(SDmp)(phen)](BAr4F) (4a, M = Rh; 4h, 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)(2)](BAr4F) (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(eta(4)-2, 4-R2C4H2S-Dmp)](BAr4F) (7a, M = Rh, R = Pr-n; 7b, M = Ir, R = Pr-n; 7c, M = Rh, R = Ph; 7d, M = Ir, R = Ph).