Synthesis, structure, spectroscopy and reactivity of silaallyl- and silapentadienyl-iridium-phosphine complexes.

摘要

A series of eta1-silaallyl- and eta1-silapentadienyl-iridium complexes have been synthesized by reacting (eta2-cyclooctene)(X)Ir(PMe 3)3 or (eta2-cyclooctene)(X)Ir(PEt 3)3 (X = Cl or Me) with vinyldimethylsilanes and butadienyldimethylsilanes, respectively, and the reactivity of these species has been investigated.;Treatment of (eta2-cyclooctene)(Cl)Ir(PMe3) 3 with (dimethylvinyl)-dimethylsilane or vinyldimethylsilane produces Si-H bond activation products, (eta1-1,1,3,3-tetramethylsilaallyl)(H)(Cl)Ir(PMe 3)3 (mer-3.1) and (eta 1-3,3-dimethylsilaallyl)(H)(Cl)Ir(PMe3)3 ( mer-3.2), respectively. Similarly, treatment of (eta2-cyclooctene)(Me)Ir(PMe3)3 with the same silane reagents yields (eta1-1,1,3,3-tetramethylsilaallyl)(H)(Me)Ir(PMe 3)3 (fac-3.3) and (eta 1-3,3-dimethylsilaallyl)-(H)(Me)Ir(PMe3)3 ( fac-3.4). Upon heating to reflux in toluene, fac-3.4 decomposes, while fac- 3.3 undergoes methane loss, followed by C-H bond activation of the terminal methyl group to form iridasilacyclopentene complex 3.5. Treatment of (eta2-cyclooctene)(Cl)Ir(PEt3) 3 with (dimethylvinyl)dimethylsilane generates (eta1-1,1,3,3-tetramethylsilaallyl)(H)(Cl)Ir(PEt 3)3 (mer-3.6), which undergoes phosphine loss to form (eta1-1,1,3,3-tetramethylsilaallyl)(H)(Cl)Ir(PEt 3)2 (3.7). The reaction between (eta 2-cyclooctene)(Me)Ir(PEt3)3 and (dimethylvinyl)dimethylsilane at -77°C produces (eta1-1,1,3,3-tetramethylsilaallyl)(H)(Me)Ir(PEt 3)3 (fac-3.8), which slowly loses (dimethylvinyl)trimethylsilane and then undergoes a second oxidative addition with another silane molecule to form a di-hydride complex fac-3.9 upon warming to room temperature. The reaction of (eta1-cyclooctene)(Me)Ir(PEt3)3 with vinyldimethylsilane forms a transient (eta1-3,3-dimethylsilaallyl)(H)(Me)Ir(PEt 3)3 (fac-3.10), which also undergoes double oxidative addition to form di-hydride complex fac-3.11.;Treatment of (eta2-cyclooctene)(Cl)Ir(PMe3) 3 with E- or (Z-butadienyl)-dimethylsilane produces, also via Si-H bond activation, (eta1-E -dimethylsilapentadienyl)(H)(Cl)Ir(PMe3)3, mer-4.1E. Similarly, treatment of (eta 2-cyclooctene)(Me)Ir(PMe3)3 with E- or (Z-butadienyl)dimethylsilane produces (eta 1-E-dimethylsilapentadienyl)(H)(Me)Ir(PMe3) 3 or (eta1-Z-dimethylsilapentadienyl)-(H)(Me)Ir(PMe 3)3, fac-4.2E or fac-4.2Z. Upon heating to 100°C (under pressure) in benzene, fac-4.2E decomposes, but fac-4.2Z loses methane and coordinates the terminal double bond of the silapentadienyl ligand, producing (eta1, eta 2-dimethylsilapentadienyl)Ir(PMe3)3, 4.3. Treatment of (eta2-cyclooctene)(Cl)-Ir(PMe 3)3 with (E-2,3-dimethylbutadienyl)dimethylsilane produces (eta1-E-2,3,5,5-tetramethylsilapentadienyl)(H)(Cl)Ir(PMe 3)3, mer-4.4E. In acetone, this species isomerizes via 2,3-dimethylbutadienyl migration from silicon to iridium, leading ultimately to production of (eta1- E-2,3-dimethylbutadienyl)(H)(SiMe2Cl)Ir(PMe3) 3, fac-4.5. Treatment of (eta 2-cyclooctene)(Cl)Ir(PMe3)3 with the Z isomer of (2,3-dimethylbutadienyl)dimethylsilane produces transient (eta1-Z-2,3,5,5-tetramethylsilapentadienyl)(H)(Cl)Ir(PMe 3)3, mer-4.4Z, which also rearranges to form an iridacyclopentene product, fac- 4.6. The reactions of (eta2-cyclooctene)-(Me)Ir(PMe 3)3 with E- or (Z-2,3-dimethylbutadienyl)dimethylsilane generate eta1-E- or (eta 1-Z-2,3,5,5-tetramethylsilapentadienyl)(H)(Me)Ir(PMe 3)3, fac-4.7E or fac-4.7Z. Heating these compounds in toluene or benzene (under pressure) leads to methane loss, followed by C-H bond activation. In the case of fac-4.7E, a silapentadienyl methyl group is activated, producing an iridasilacyclopentene product, fac-4.9. In the case of fac- 4.7Z, a C-H bond on the end of the silapentadienyl chain is activated, producing the first example of an iridasilacyclohexadiene, fac- 4.10. X-ray crystal structures of (eta 2-cyclooctene)-(Me)Ir(PMe3)3, mer- 3.1, fac-3.3, fac-3.5, fac-3.11 , mer-4.1E, 4.3, fac-4.5, fac-4.6 , fac-4.7E, and fac-4.8 are reported.