Structural Aspects of Chlorine-Aluminium Alkoxides

Authors

  • Prof. Dr. Dr. Michael Veith,

    1. INM – Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbruecken, Germany
    2. Institute for Inorganic Chemistry, Saarland University, Postfach 15 11 50, 66041 Saarbruecken, Germany
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  • Hameed Ullah Wazir,

    1. INM – Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbruecken, Germany
    2. Institute for Inorganic Chemistry, Saarland University, Postfach 15 11 50, 66041 Saarbruecken, Germany
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  • Tatjana Kirs,

    1. INM – Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbruecken, Germany
    2. Institute for Inorganic Chemistry, Saarland University, Postfach 15 11 50, 66041 Saarbruecken, Germany
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  • Volker Huch,

    1. Institute for Inorganic Chemistry, Saarland University, Postfach 15 11 50, 66041 Saarbruecken, Germany
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  • Michael Zimmer

    1. Institute for Inorganic Chemistry, Saarland University, Postfach 15 11 50, 66041 Saarbruecken, Germany
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  • In Memory of Professor Hans Georg von Schnering

Abstract

LiAlH4 and AlCl3 reacted in a ratio 1:3 to obtain Cl2AlH, which is stabilised by the addition of two equivalents of N-methylpiperidine (nmp) to form dichloroalane (1) as bis adduct of nmp. Compound 1 was allowed to react with 2,6-tBu-4-MeC6H2OH and HOcHex in a 1:1 ratio to get compounds 2 and 3, respectively. Cl2Al(2,6-tBu-4-MeC6H2O)(nmp) (2) is a monomer in which the central aluminium atom is tetracoordinate. Contrary to the parent compound 1, compound 2 is stabilised by only one nmp molecule. The larger bulk of the alkoxide in 2 prevents the second nmp molecule to reach the aluminium atom. Compound 3 crystallises as unique anionic tri-nuclear aluminium entity [Al3Cl6(OR)4] [nmp2H]+ with a protonated nmp as countercation. The lesser bulk of the cyclohexanolate leads to a higher oligomerisation of ROAlCl2 (R = cyclohexyl). When a relatively bulkier alcohol, 1-methylcyclohexanol, was allowed to react with mixtures of LiAlH4 and AlCl3 prepared in 1:1 and 1:3 ratios in solution, compounds 4 and 5, respectively, were obtained. Both compounds ((HClAlOR)2 (4) and (Cl2AlOR)2 (5), R = cHexMe-1)) are dimers with oxygen as bridging atom in the Al2O2 rings. All compounds 2, 3, 4, and 5 were structurally characterised by X-ray diffraction on single crystals.

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