Half-sandwich complexes ,/ Iridium complexes ,/ cyclo-Sulfido ligands / cyclo-Selenido ligands / Iridacycles ~~ ~~ Cp*Ir(PMe3)C12 (1) reacts with chalcogenide ligand sources such as (NH4)& (x x lo), (NEt&Se6, and H,Se to yield the half-sandwich complexes Cp*Ir(PMe,)(S,) In = 4 (2a), 6 (4a)l and Cp*Ir(PMe,)(Se,) [n = 2 (5b), 4 (2b)l. Desulfurization of 4a
by PPh3 leads to Cp*Ir(PMe,)(S,) (3a), while both 4a and 3a react with excess P(nBu), to give 2a. The geometries of the cyclo-oligochalcogenide ligands in 4a and 2b have been determined by X-ray crystallography.
Among the numerous transition metal cyclopentadienyl complexes with (unsubstituted) sulfur and selenium') ligands, iridium compounds are missing so far. We therefore report on some mononuclear Cp*Ir complexes which we have obtained starting from Cp*Ir(PMe,)Cl, (1) (abbreviations: Cp = q5-cyclopentadienyl, q5-C5H5; Cp' = q5-C5H4Me; Cp" = q5-C5Me5).
Results and Discussion
Bergman and co-workers6) have found that the two halide ligands of 1 can be replaced by mercapto and alkylthio nucleophiles to give complexes of the type c ~* l r ( P M e ~) ( s R ) ~ (R = H, Me, tBu). We have similary observed that 1 reacts with ammonium polysulfide, (NH4)2S, (x x lo), in chloroform solution to produce a mixture of two cyclo-oligosulfido complexes Cp*Ir(PMe3)(S4) (2a) and Cp*Ir(PMe3)(S6) (4a) in
Me3P
'CI