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Issue 1, 1979
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Alkyl-bridged complexes of the d- and f-block elements. Part 1. Di-µ-alkyl-bis(η-cyclopentadienyl)metal(III)dialkylaluminium(III) complexes and the crystal and molecular structure of the ytterbium methyl species

Abstract

Reaction of [{M(η-C5H5)2Cl}2] with Li[AlR4], or in some cases Mg[AlR4]2, affords the novel crystalline complexes [(η-C5H5)2M(µ-R)2AlR2](M = Sc, Y, Gd, Dy, Ho, Er, Tm, or Yb, R = Me; or M = Sc, Y, or Ho, R = Et). The yttrium, unlike the scandium, complexes are fluxional at 40 °C, but at –40 °C bridging and terminal alkyl groups give distinct n.m.r. signals; ΔG for site exchange in [(η-C5H5)2Y(µ-Me)2AlMe2] is 15.9 kcal mol–1 at 392 K. A di-µ-alkyl-bridged structure is confirmed by i.r. (bridging CH3 band at 1 250 and 1 235 cm–1), variable-temperature 1H and 13C n.m.r. (M = Sc or Y), and X-ray studies (M = Yb). Additional data are given on the less stable [(η-C5H5)2Ti(µ-Me)2AlMe2], [Ti(η-C5H5)2(AlMe3Cl)], and [(η-C5H5)2Ti(µ-H)2AlMe2](structure deduced in part from e.s.r. spectra). A single-crystal X-ray analysis of [(η-C5H5)2Yb(µ-Me)2AlMe2] has been carried out to R 0.036 and R′ 0.042; the complex has an approximately tetrahedral Yb and Al environment (space group Pna21) with the YbMe2Al unit strikingly similar to AlMe2Al in [Al2Me6]. Important bond lengths (t = terminal, b = bridge) and angles are: Yb–C (cyclopentadienyl, average) 2.61(3), Yb–Cb 2.59(3), Al–Cb 2.18(5), and Al–Ct 2.00(1)Å; Yb–C–Al 79.9(1.6) and C–Al–C 113.3(8)°.

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Article type: Paper
DOI: 10.1039/DT9790000045
J. Chem. Soc., Dalton Trans., 1979, 45-53

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    Alkyl-bridged complexes of the d- and f-block elements. Part 1. Di-µ-alkyl-bis(η-cyclopentadienyl)metal(III)dialkylaluminium(III) complexes and the crystal and molecular structure of the ytterbium methyl species

    J. Holton, M. F. Lappert, D. G. H. Ballard, R. Pearce, J. L. Atwood and W. E. Hunter, J. Chem. Soc., Dalton Trans., 1979, 45
    DOI: 10.1039/DT9790000045

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