Organometallic Selenolates. IX. (18-Crown-6)-potassium (η⁵-cyclopentadienyl)bis(1,4-tetraselenido-Se¹,Se⁴)tungstate(IV)

The title compound, [(18-crown-6) K]⁺[W(η⁵-C₅H₅)(η²-Se₄)₂]⁻ or [K(C₁₂H₂₄O₆)][W(C₅H₅)(Se₄)₂], consists of the anion [CpW(Se₄)₂]⁻ (where Cp is cyclopentadienyl), which is linked to the [(18-crown-6)K]⁺ cation via two potassium–selenium contacts of 3.457 (5) and 3.527 (5) Å. One of the WSe₄ rings adopts an envelope conformation, whereas the other WSe₄ ring lies between the standard envelope and half-chair conformations. The corresponding W—Se bond lengths lie in the range 2.441 (2)–2.570 (2) Å, indicating asymmetry in the chelation of both Se₄ ligands, which can also be seen from the Se—Se bond-length range of 2.300 (4)–2.447 (3) Å.

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