Metal-dependent stabilization of Si-S bonds to hydrolysis in iridium and rhodium silyls. Hydrolyzability as a probe for Si-H reductive elimination

Michael Aizenberg, Roman Goikhman, David Milstein

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Abstract

The iridium (triethylthio) silyl complexes cis(PPh3)2(CO)IrH2(Si(SEt)3) (5), fac-(PMe3)3Ir(CH3(H)-(Si(SEt)3) (6), and mer-(PMe3)3Ir(C6F5)(H)(Si(SEt) 3) (7) were synthesized by oxidative addition of HSi(SEt)3 (1) to HIr(CO)(PPh3)3 (2), CH3Ir(PMe3)4 (3), and C6F5-Ir(PMe3)3 (4), respectively. 4 was synthesized by the reaction between Ir(PMe3)4Cl and C6F5MgBr. The rhodium analog of 7, mer-(PMe3)3Rh(C6F5)(H)(Si(SEt) 3) (9), was obtained similarly from C6F5Rh(PMe3)3, (8) and 1. Unlike the extremely easily hydrolyzable parent silane 1, compounds 5-7 are stable in H2O/THF and even in NaOH/H2O/THF solutions. This stabilization is attributed to the electron-donating capacity of the Ir centers, which efficiently reduces electrophilicity of the silicon. Reactivity of the rhodium complex 9 is strikingly different, cleanly producing in the presence of 5 equiv of H2O the ethylthio-complex mer-(PMe3)3Rh(C6F5)(H)(SEt) (10). Compound 10 was identified spectroscopically and was synthesized independently from 8 and HSEt. A plausible scheme accounting for the generation of 10 under the hydrolysis conditions is presented. The observed difference in the reactivities of 5-7 and 9 is explained in terms of their different tendencies to reductively eliminate H-Si(SEt)3.

Original languageEnglish
Pages (from-to)1075-1078
Number of pages4
JournalOrganometallics
Volume15
Issue number3
Publication statusPublished - Feb 6 1996

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ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry

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