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

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posted on 03.04.2001, 00:00 by Dagmara A. Ortmann, Olaf Gevert, Matthias Laubender, Helmut Werner
In contrast to trans-[IrCl(C2H4)(SbiPr3)2] (2), which has been obtained from [IrCl(C2H4)2(SbiPr3)2] (1) by abstraction of ethene together with some byproducts, the corresponding cycloocteneiridium(I) complex trans-[IrCl(C8H14)(SbiPr3)2] (4) can be prepared from [IrCl(C8H14)2]2 (3) and 4 equiv of SbiPr3 in excellent yield. Compound 4 rearranges in hexane at room temperature to anti,exo-[IrHCl(η3-C8H13)(SbiPr3)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(η3-C3H5)(SbiPr3)2] (6a) and anti,exo-[IrHCl(η3-C6H11)(SbiPr3)2] (7), respectively. Similarly to 5a, also 6a isomerizes to endo-[IrHCl(η3-C3H5)(SbiPr3)2] (6b). The reaction of 6a with HCl leads to the formation of [IrHCl2(SbiPr3)2] (8), which forms the 1:1 adduct 9 with C2H4. The preparation of other bis(triisopropylstibine)iridium complexes 1012 has been achieved by using 4 as the starting material. Compounds 5a and 6a have been characterized crystallographically.