Darstellung von trans-[Mo6Cl8]Cl4Br22−ausgehend von kristallisierten [Mo6Cl8]Cl4(H2O)2 und die Kristallstruktur von [(C6H5)4As]2[Mo6Cl8]Cl4Br2 |
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Authors: | Harald Schufer Claus Brendel Gerald Henkel Bernt Krebs |
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Institution: | Harald Scháufer,Claus Brendel,Gerald Henkel,Bernt Krebs |
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Abstract: | Preparation of trans-Mo6Cl8]Cl4Br22? Starting from Crystalline Mo6Cl8]Cl4(H2O)2 and Crystal Structure of (C6H5)4As]2Mo6Cl8]Cl4Br2 The synthesis of the title compound is successful if the crystallized (Mo6Cl8)Cl4(H2O)2] containing the H2O molecules in trans-position reacts with HBr + (C6H5)4As]Br in ethanol in a heterogeneous reaction. The X-ray structure investigation confirms the existence of discrete trans-Br-substituted cluster anions of composition (Mo6Cl8)Cl4Br2]2? in the crystal. The reaction in homogeneous solutions proceeds to Br-enriched compounds. (C6H5)4As]2(Mo6Cl8)Cl4Br2] crystallizes in the triclinic space group P¯1 with a = 11.071(2), b = 11.418(2), c = 12.813(2) Å, α = 116.10(2), β = 95.27(2) and γ = 94.41(2)° (?133°C). The crystal structure at ?133°C was determined from single crystal X-ray diffraction data (R1 = 0.026). The (Mo6Cl8)Cl4Br2]2?-anions are not completely ordered but distributed statistically among the three positions which are possible within the limits of the ordered Mo6Cl8]-cores (ratio 11:5:4). The frameworks of the anions consist of Mo6 cluster units with (slightly distorted) octahedral arrangement of the metal atoms (d(Mo? Mo): 2.600(1) up to 2.614(1) Å), which are coordinated by the halogeno ligands in a square-pyramidal manner. The details of the structure will be discussed and compared with similar (Mo6X8)Y4] cluster units (X, Y ? Cl, Br). |
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