Potassium thiapentadienide (K'CfldsS") reacts cleanly with ClIr(PMe3)3 in tetrahydrofuran at room temperature to generate ((l,2,5-?;)-5-thiapentadienyl)Ir(PMe3)3 (1). Treatment of 1 with H+BF4~OEt2 leads to protonation at Cl and production of [((2,3,4,5-^)-5-thiapentadiene)-Ir(PMe3)s]+BF4_ (2), while treatment with CH3O3SCF3 results in methylation at sulfur and production of [((l,2,5-77)-5-methyl-5-thiapentadienyl)Ir( PMe3)3]+03SCF3_ (3). Compound 3 isomerizes to [((l,2,3,4-^)-5-methyl-5-thiapentadiene)Ir(PMe3)3]+03SCF3_ (4) at room temperature. Upon heating in toluene at reflux, compound 1 slowly converts to the iridathia-1-1 cyclopentene complex mer-CH2=C-CH-CH-S-Ir(PMe3)3(H) (5), via intramolecular activation of the C-H2 bond. Like compound 1, 5 undergoes protonation at Cl when treated with H~BF4-,OEt2, producing the "iridathiophene" complex, [7ner-CH3-C-CH-CH-S-Ir-(PMe3)3(H)]+BF4" (6), but undergoes methylation at sulfur when treated with CH3O3SCF3, generating [mer-CH2=C-CH=CH-S(CH3)-ir(PMe3)3(H)]+03SCF3- (7). ((l,2,5-?7)-5-Thiapentadienyl)Ir( PEt3)3 ( 8), the tris(PEt3) analogue of 1, is produced upon reacting potassium thiapentadienide with ClIr(PEt3)3. Unlike 1, it undergoes intramolecular C-H bond activation upon stirring in tetrahydrofuran at room temperature. Initially, a mixture of the C-Hl bond activation product, mer-CH=CH-CH=CH-S-Ir(PEt3)3(H) (9), and the C-H2 1 1 bond activation product, mer-CH2=C-CH=CH-S-Ir(PEt3)3(H) (10), are produced. However, the six-membered ring compound (9) gradually converts to the thermodynamically-preferred five-membered ring compound (10). Like its tris(PMe3) analogue ( 5), compound 10 reacts
