Catalytic and stoichiometric reactions of tertiary silanes with [Ir(Me)2Cp*L] (Cp*=η5-C5Me5; L=PMe3, PMe2Ph, PMePh2, PPh3) in the presence of one-electron oxidants. A unique case of SiH, SiC, IrC and PF bonds one-step activation: crystal structure of [Ir(Ph)(SiPh2F)Cp*(PMe3)]

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Abstract

The iridium(III) dimethyl derivatives [Ir(Me)2Cp*L] (Cp*=η5-C5Me5; L=PMe3 1a, PPh3 1d) catalyze the dehydrogenative coupling of dimethylphenylsilane in the presence of one-electron oxidants to yield Me2PhSiSiPhMe2. Compounds 1a–d react with triphenylsilane in the presence of [FeCp2]PF6 to give methane and [Ir(Ph)(SiFPh2)Cp*L] (L=PMe3 (2a), PMe2Ph (2b), PMePh2 (2c), PPh3 (2d)). 2a was structurally characterized by single-crystal X-ray diffraction experiments. The ‘three-legged piano stool’ coordination polyhedron is slightly deformed.

Introduction

We have described in previous papers [1] the reactions of the Ir(III) dimethyl complexes [Ir(Me)2Cp*L] (L=PMe3 (1a), PMe2Ph (1b), PMePh2 (1c), PPh3 (1d)) with arenes under oxidative conditions to give methane and the corresponding methylaryl derivatives [Ir(Me)(Ar)Cp*L] via a ‘σ-bond metathesis’ reaction of IrC and CH bonds. With the aim to extend the applicability of this reaction we have moved our attention to the activation of SiH bonds, which are known to undergo a variety of catalytic [2] and stoichiometric [3] reactions in the presence of transition metals. Here we report that the above iridium derivatives in the presence of one-electron oxidants are able to catalyze the deydrogenative coupling of PhMe2SiH to the disilane and react with Ph3SiH to give new iridium complexes resulting from a novel one-step rearrangement of SiH, SiC, IrC, and PF bonds.

Section snippets

Results and discussion

The reaction of PhMe2SiH in the presence of catalytic amounts of 1a or 1d and one-electron oxidants ([FeCp2]PF6, AgBF4) in CH2Cl2 showed formation of the product of dehydrogenative coupling PhMe2SiSiMe2Ph (Table 1):2PhMe2SiH→PhMe2SiSiMe2Ph+H2Compound 1a proved to be a better catalyst precursor than 1d. The yields depend significantly on the temperature and on silane/catalyst ratio, being quite low (2%) at room temperature (r.t.) and at a silane/iridium ratio of 1000, but increasing remarkably

Experimental

The reactions and manipulation of organometallics were carried out under dinitrogen or argon, using standard techniques. The solvents were dried and distilled prior to use. The compounds [Ir(Me)2Cp*(L)] (L=PMe3 (1a) [1b], PMe2Ph (1b) [1c], PMePh2 (1c) [1c], PPh3 (1d) [1b]), were prepared according to literature procedures. Commercial reagents, AgBF4, [FeCp2]PF6, Ph3SiH, PhMe2SiH and Ph2MeSiH were used as supplied. 1H, 13C, 31P, 19F, 2H-NMR spectra were recorded on Varian Gemini 200 and VXR 300

Supplementary material

Crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic Data Center, CCDC No. 124099 for compound 2a. A full list of observed and calculated structure factors has been deposited with the editor as supplementary material and is available upon request. Geometric calculations have been made by means of the parst-97 program [17].

Acknowledgements

This work was supported by the CNR (Rome).

References (17)

  • (a) P. Diversi, S. Iacoponi, G. Ingrosso, F. Laschi, A. Lucherini, P. Zanello, J. Chem. Soc. Dalton Commun. (1993) 351....
  • (a) K.A. Brown-Wensley, Organometallics 6 (1987) 1590. (b) L.S. Chang, J.T. Corey, Organometallics 8 (1989) 1885. (c)...
  • J.Y. Corey et al.

    Chem. Rev.

    (1999)
  • (a) M.D. Curtis, P.S. Epstein, Adv. Organomet. Chem. 19 (1981) 213. (b) S.K. Grumbine, T.D. Tilley, J. Am. Chem. Soc....
  • (a) M. Tanaka, T. Kobayashi, T. Hayashi, T. Sakakura, Appl. Organomet. Chem. 2 (1988) 91. (b) H. Yamashita, M. Tanaka,...
  • J.E. Veltheer et al.

    J. Am. Chem. Soc.

    (1995)
  • S.E. Johnson et al.

    Inorg. Chem.

    (1989)
  • (a) L. Andreucci, P. Diversi, G. Ingrosso, A. Lucherini, F. Marchetti, V. Adovasio, M. Nardelli, J. Chem. Soc. Dalton...
There are more references available in the full text version of this article.

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