Inorganic Chemistry

Transition-Metal-Stabilised Heavy Tetraphospholide Anions

Authors

  • John A. Kelly University of Regensburg, Institute of Inorganic Chemistry, 93040 Regensburg, Germany ,
  • Verena Streitferdt University of Regensburg, Institute of Organic Chemistry, 93040 Regensburg, Germany ,
  • Maria Dimitrova University of Helsinki, Department of Chemistry, Faculty of Science, FI-00014 University of Helsinki, Finland ,
  • Ruth M. Gschwind University of Regensburg, Institute of Organic Chemistry, 93040 Regensburg, Germany ,
  • Raphael Berger Paris-Lodron University Salzburg, Department for Chemistry and Physics of Materials, 5020 Salzburg, Austria ,
  • Robert Wolf University of Regensburg, Institute of Inorganic Chemistry, 93040 Regensburg, Germany

Abstract

Phosphorus analogues of the ubiquitous cyclopentadienyl (Cp) are a rich and diverse family of compounds, which have found widespread use as ligands in organometallic complexes. By contrast, phospholes incorporating heaviear group 14 elements (Si, Ge, Sn, and Pb) are hardly known. Here, we demonstrate the isolation of the first metal complexes featuring heavy cyclopen-tadienyl anions (SnP4)2─ and (PbP4)2─. The complexes [(η4-tBu2C2P2)2Co2(μ,η5:η5-P4Tt)] [Tt = Sn (6), Pb (7)] are formed by reaction of white phosphorus (P4) with cyclooctadiene cobalt complexes [Ar′TtCo(η4-P2C2tBu2)(η4-COD)] [Sn (2), Pb (3), Ar′ = C6H3-2,6{C6H3¬-2,6-iPr2}2, COD = cycloocta-1,5-diene] and Tt{Co(η4-P2C2tBu2)(COD)}2 [Tt = Sn (4), Pb (5)]. While the (SnP4)2− complex 6 was isolated as a pure and stable compound, compound 7 eliminates Pb(0) below room temper-ature to afford [(η4-tBu2C2P2)2Co2(μ,η4:η4-P4) (8), which is a rare example of a tripledecker complex with a (P4)2─ middle deck. The electronic structures of 6-8 are analysed using theoretical methods, including an analysis of intrinsic bond orbitals and magnetic response theory. Thereby the aromatic nature of (P5)− and (SnP4)2− was confirmed, while for (P4)2− a specific type of symmetry-induced weak paramagnetism was found which is distinct from conventional antiaromatic species.

Content

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Supplementary material

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Supporting Information
Details on the synthesis and characterization of compounds 1-8, X-ray crystallographic data, NMR and UV-vis spectroscopic data, and results of quantum chemical calculations