Synthesis and Characterization of Coordinately Unsaturated Phosphine Complexes of Divalent V, Cr, Mn, Fe, and Co. Crystal Structures of [CrCl2(dippe)]2 and FeCl2(dippe)

Ann R. Hermes, Gregory S. Girolami

Research output: Contribution to journalArticle

Abstract

The reaction of divalent transition-metal halides with the bulky chelating phosphine 1,2-bis(diisopropylphosphino)ethane, dippe, gives a series of coordinately unsaturated complexes of stoichiometry MX2(dippe) for = V, Cr, Mn, Fe, or Co. Both the vanadium(II) and chromium(II) complexes readily form adducts with tetrahydrofuran or acetonitrile. The base-free chromium species exists as a dimer in the solid state, [CrCl2(dippe)]2, that consists of two square-planar chromium centers arranged in pairs via asymmetric chloride bridges. Averaged distances for the two independent molecules are as follows: Cr…Cr = 3.605 (2) Å Cr-P = 2.481 (2), 2.511 (2) Å; Cr-Cl(t) = 2.333 (2) Å; Cr-Cl(b) = 2.380 (2), 2.606 (2) Å. Crystal data for Cr2Cl4P4C28H64: space group PI, a = 13.225 (2) Å, b = 14.834 (3) Å, c = 11.101 (2) Å, α = 97.35 (1)°, β = 114.21 (1)°, γ = 84.26 (1)°, V = 1967.3 (6) Å3, Z = 2, RF = 4.2%, RwF = 4.7% on 3435 reflections and 344 variables. The manganese, iron, and cobalt complexes are all tetrahedral monomers, as confirmed by the X-ray crystal structure of FeCl2(dippe): Fe-P = 2.46 (1) Å, Fe-Cl = 2.21 (1) Å P-Fe-P = 83.8 (3)°, Cl-Fe-Cl = 117.1 (4)°. Crystal data for FeCl2P2C14H32: space group Pica, a = 24.66 (1) Å, b = 22.67 (1) Å, c = 14.995 (6) Å, V = 8385 (8) Å3, Z = 16, RF = 12.0%,RWF = 12.6% on 1547 reflections and 201 variables. NMR and EPR studies show that all of the four-coordinate species exist in high-spin electronic configurations. The MX2(dippe) complexes provide an excellent opportunity to examine the behavior of coordinately unsaturated first-row transition-metal species and serve as excellent starting materials for the preparation of low-electron-count organometallic derivatives of these elements.

Original languageEnglish (US)
Pages (from-to)1775-1781
Number of pages7
JournalInorganic Chemistry
Volume27
Issue number10
DOIs
StatePublished - Jan 1 1988

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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