Preparation of half-sandwich ethylene complexes of Osmium(II)

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Abstract

Ethylene complexes [OsCl(η6-p-cymene)(η2-CH2double bondCH2)L]BPh4 (1, 2) [L = P(OMe)3, P(OEt)3, PPh(OEt)2, tBuNC) were prepared by allowing the dichloro compounds OsCl26-p-cymene)L to react with CH2double bondCH2 in mild conditions (1 atm). Treatment of 1 with amine or hydrazine yielded [OsCl(p-tolyl-NH2)(η6-p-cymene){PPh(OEt)2}]BPh4 (3) or [OsCl(η6-p-cymene)(CH3NHNH2){PPh(OEt)2}]BPh4 (4) derivatives. The vinylidene cation [OsCl{double bondCdouble bondC(H)Ph}(η6-p-cymene){PPh(OEt)2}]+ (5+) was also prepared from 1 and PhCtriple bondCH. The complexes were characterized spectroscopically and by X-ray crystal structure determination of [OsCl(η6-p-cymene)(η2-CH2double bondCH2){P(OMe)3}]BPh4 (1a). The nature of the Os–ethylene bond was investigated from a computational point of view.

Graphical abstract

Preparation and X-ray crystal structure determination of ethylene complexes of osmium(II) are described.

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Highlights

► Synthesis of half-sandwich ethylene complexes of osmium under mild conditions. ► Spectroscopic and crystallographic characterization of η2-ethylene derivatives. ► DFT calculations.

Introduction

The coordination of an alkene to a transition metal fragment occupies an important place in organometallic chemistry [1], [2], not only due to the significant changes in structure and chemical reactivity that the alkene coordination to a central metal may induce [3], [4], but also due to the influence that the metal fragment may have in its catalytic transformations [5]. A number of alkene complexes have been prepared [1], [3], [4], [6] for different central metals with various types of ligands, in order to probe the most important factors which influence the stability of the coordinated alkene and its reactivity in stoichiometric and catalytic organic reactions.

However, the number of reported alkene complexes for the metals of the iron triad is still limited, compared with other metal triads [7] such as those of cobalt and nickel, and the known ethylene complexes for osmium are still few [8].

We have a long-standing interest in the chemistry of arene complexes [9] of the iron triad and, during our studies on the reactivity of p-cymene complexes of osmium, we found that ethylene may coordinate to the metal fragment [OsCl(η6-p-cymene)L]+ (L = phosphite) in very mild conditions.

We report here the results of these studies, including the synthesis and characterization of ethylene complexes of osmium stabilized by the p-cymene ligand.

Section snippets

General comments

All synthetic work was carried out in an appropriate atmosphere (Ar, N2) using standard Schlenk techniques or an inert atmosphere dry-box. Once isolated, the complexes were found to be relatively stable in air, allowing their characterization; nonetheless they were stored under nitrogen at −25 °C. All solvents were dried over appropriate drying agents, degassed on a vacuum line, and distilled into vacuum-tight storage flasks. OsO4 was a Pressure Chemical Co. (USA) product, used as received.

Results and discussion

Ethylene reacts in mild conditions (1 atm, room temperature) with dichloro complexes OsCl26-p-cymene)L in the presence of NaBPh4 to give η2-ethylene derivatives [OsCl(η6-p-cymene)(η2-CH2double bondCH2)L]BPh4 (1), which were isolated as yellow solids and characterized (Scheme 1).

Important for successful synthesis was the presence of the salt NaBPh4, which probably favors substitution of the chloride ligand in the starting complexes, thus allowing derivatives 1 to be obtained in good yields.

Studies of the

Conclusions

In this paper we report the preparation of ethylene complexes of osmium stabilised by the p-cymene ligand. The facile substitution of the η2-CH2double bondCH2 ligand allowed new half-sandwich derivatives to be obtained. The structural parameters and the nature of the Os–ethylene bond in the ethylene complexes are also discussed.

Acknowledgments

The authors wish to thank MIUR (PRIN2009) for financial support and CINECA Award N. HP10CI3CHF (2010) for making available high-performance computing resources and support. Thanks also go to Mrs. Daniela Baldan, from the Università Ca’ Foscari Venezia (Italy), for technical assistance.

References (30)

  • D.M.P. Mingos
  • J.P. Collman et al.

    Principles and Applications of Organotransition Metal Chemistry

    (1987)
    R.H. Crabtree

    The Organometallic Chemistry of Transition Metals

    (1986)
    A. Yamamoto

    Organotransition Metal Chemistry

    (1986)
    Ch. Elschenbroich et al.

    Organometallics – A Concise Introduction

    (1992)
  • M. Bochmann

    Organometallics 2-Complexes with Transition Metal-Carbon π-Bonds

    (2004)
  • S.G. Kukolich

    J. Am. Chem. Soc.

    (1995)
    A.J. Pearson

    Metallo-Organic Chemistry

    (1985)
  • G.W. Parshal et al.

    Homogeneous Catalysis

    (1992)
    P.W.N.M. Van Leeuwen

    Homogeneous Catalysis: Understanding the Art

    (2004)
  • Y. Borguet et al.

    Organometallics

    (2010)
    J. Wolf et al.

    Organometallics

    (2008)
    C. Karunatilaka et al.

    Chem. Soc.

    (2007)
    B.J. Drouin et al.

    J. Am. Chem. Soc.

    (1999)
    I. De los Rios et al.

    Organometallics

    (1996)
    J. Li et al.

    Inorg. Chem.

    (1995)
    B.E. Cavit et al.

    J. Chem. Soc. Chem. Commun.

    (1972)
  • S. Stahl et al.

    Organometallics

    (1990)
    B.R. Bender et al.

    Organometallics

    (1992)
    T.J. Johnson et al.

    Inorg. Chem.

    (1994)
    L. Pu et al.

    J. Am. Chem. Soc.

    (1993)
    W.K. Leong et al.

    J. Cluster Sci.

    (1996)
    M.A. Esteruelas et al.

    Organometallics

    (2000)
    D.V. Yandulov et al.

    Organometallics

    (2001)
    T. Shima et al.

    Organometallics

    (2005)
    R. Castro-Rodrigo et al.

    J. Am. Chem. Soc.

    (2010)
    R. Castro-Rodrigo et al.

    Organometallics

    (2010)
    S. Bajo et al.

    Organometallics

    (2011)
  • G. Albertin et al.

    Organometallics

    (2011)
    G. Albertin et al.

    Organometallics

    (2011)
    G. Albertin et al.

    Eur. J. Inorg. Chem.

    (2011)
    G. Albertin et al.

    J. Organomet. Chem.

    (2010)
    G. Albertin et al.

    J. Organomet. Chem.

    (2010)
    G. Albertin et al.

    Eur. J. Inorg. Chem.

    (2009)
    G. Albertin et al.

    Organometallics

    (2009)
  • R. Rabinowitz et al.

    J. Org. Chem.

    (1961)
  • R. Appel et al.

    Angew. Chem. Int. Ed.Engl.

    (1971)
  • ...
  • J.A. Cabeza et al.

    J. Chem. Soc. Dalton Trans.

    (1985)
  • BrukerAXS et al.

    Bruker Analytical X-ray Systems

    (1995)
  • G.M. Sheldrick

    SADABS, Program for Absorption Correction

    (1996)
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