Square-Planar Bis(triisopropylstibine)(olefin)iridium(I) Complexes and Their Rearrangement to (η3-Allyl)hydridoiridium(III) Isomers

In contrast to trans -[IrCl(C 2 H 4 )(Sb i Pr 3 ) 2 ] ( 2 ), which has been obtained from [IrCl(C 2 H 4 ) 2 (Sb i Pr 3 ) 2 ] ( 1 ) by abstraction of ethene together with some byproducts, the corresponding cycloocteneiridium(I) complex trans -[IrCl(C 8 H 14 )(Sb i Pr 3 ) 2 ] ( 4 ) can be prepared from [IrCl(C 8 H 14 ) 2 ] 2 ( 3 ) and 4 equiv of Sb i Pr 3 in excellent yield. Compound 4 rearranges in hexane at room temperature to anti,exo -[IrHCl(η 3 -C 8 H 13 )(Sb i Pr 3 ) 2 ] ( 5a ), which in benzene is in equilibrium with the anti,endo isomer 5b . Compound 5a is generated from 4 even in the solid state. Treatment of 4 with propene and 1-hexene results in the displacement of cyclooctene and affords exo- [IrHCl(η 3 -C 3 H 5 )(Sb i Pr 3 ) 2 ] ( 6a ) and anti,exo -[IrHCl(η 3 -C 6 H 11 )(Sb i Pr 3 ) 2 ] ( 7 ), respectively. Similarly to 5a, also 6a isomerizes to endo- [IrHCl(η 3 -C 3 H 5 )(Sb i Pr 3 ) 2 ] ( 6b ). The reaction of 6a with HCl leads to the formation of [IrHCl 2 (Sb i Pr 3 ) 2 ] ( 8 ), which forms the 1:1 adduct 9 with C 2 H 4 . The preparation of other bis(triisopropylstibine)iridium complexes 10 − 12 has been achieved by using 4 as the starting material. Compounds 5a and 6a have been characterized crystallographically.