This work was supported by the National Science Foundation (grant No. DMR 88-03382). MRP and ROW thank the Boeing Company and the National Science Foundation (grant No. CHE-8408407) for establishment of the crystal structure laboratory at Wa hington State University. GLG acknowledges gratefully the support of the donors of the Petroleum Research Fund, administered by the American Chemical Society.
Acta Crystallographica Section C
Crystals -- Structure, Chemical bonds, Crystallography
2C₄H₅N₂O⁺.Cr₂O²₇⁻, Mᵣ=410∙2, monoclinic, P2₁, a=8∙(2), b=6∙132 (2), c=14∙493 (4) Å, β=94∙50 (2)°, V=708∙8 (3) Å³, Z=2, Dₓ=1∙92 g cm⁻³, Mο Κα, λ=0∙71069 Å, μ=15∙5 cm⁻¹, F(000)=412, T=293 K, R=0∙0602 for 1980 unique observed reflections with F≥3σ(F). The structure consists of discrete dinegative dichromate anions hydrogen bonded to monopositive pyrazinium N-oxide cations (N―H∙∙∙O=2∙724, 2∙644 Å). A strong hydrogen bond to the bridging O atom in the Cr₂O²₇⁻ anion leads to significant lengthening of the bridging Cr―O bonds. A short C―H∙∙∙O interaction (3∙180 Å) is also observed.
Gard, Gary, Pressprich, M. R., Willett, R. D., Paudler, W. W., Sheets, R. M. (1990) Bis(1H+-Pyrazinium N4-Oxide) Dichromate. Acta Crystallographica Section C: Crystal Structure Communications. 46, 1635.