Modeling the proposed intermediate in alkane carbon-hydrogen bond activation by Cp{sup *}(PMe{sub 3})Ir(Me)OTf: Synthesis and stability of novel organometallic iridium(V) complexes
- Univ. of California, Berkeley, CA (United States). Dept. of Chemistry
Addition of HX to CH{sub 2}Cl{sub 2} solutions of Cp{sup *}IrMe{sub 4} (Cp{sup *} = {eta}{sup 5}-C{sub 5}Me{sub 5}) at low temperature provided Cp{sup *}Ir(Me){sub 3}X (X = Cl, 5; X = OSO{sub 2}CF{sub 3} = OTf, 6). Both complexes are very thermally sensitive yet proved to be useful precursors for novel cationic iridium(V) complexes. Treatment of 6 with a variety of trisubstituted phosphines, arsines, and stibines (L) afforded compounds 7--12, [Cp{sup *}(L)IrMe{sub 3}][OTf] (L = PMe{sub 3}, 7; L = PEt{sub 3}, 8; L = PPh{sub 3}, 9; L = AsEt{sub 3}, 10; L = AsPh{sub 3}, 11; L = SbPh{sub 3}, 12). Metathesis of the triflate anion of antimony complex 12 for the tetraphenylborate anion afforded [Cp{sup *}(SbPh{sub 3})IrMe{sub 3}][BPh{sub 4}] (13). The molecular structure of 13 was determined by single-crystal X-ray diffraction analysis. Complex 7 is a potential model for the proposed intermediate on the methane carbon-hydrogen bond activation reaction pathway by Cp{sup *}(PMe{sub 3})Ir(Me)OTf, and its relevance to this reaction is discussed. Complex 7 decomposed by reductive elimination of MeCp{sup *}. The remaining iridium fragment was trapped by added phosphine to form [cis-{l_brace}PMe{sub 3}{r_brace}{sub 4}IrMe{sub 2}][OTf] (14) as an impure mixture. Reaction of 6 with excess dppm (dppm = Ph{sub 2}PCH{sub 2}PPh{sub 2}) afforded [cis-{l_brace}{eta}{sup 2}-Ph{sub 2}PCH{sub 2}PPh{sub 2}{r_brace}{sub 2}IrMe{sub 2}][OTf] (15). The molecular structure of 15 was determined by single-crystal X-ray structure analysis.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 682120
- Journal Information:
- Organometallics, Journal Name: Organometallics Journal Issue: 14 Vol. 18; ISSN ORGND7; ISSN 0276-7333
- Country of Publication:
- United States
- Language:
- English
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