Structure of tris(cyclohexylammonium) phosphoenolpyruvate monohydrate and crystal chemistry of phosphoenolpyruvates

The crystal structure of (C₆H₁₁NH₃⁺)₃.Pep³⁻.H₂O, where Pep³⁻ = (O⁻)₂P(O)—O—C(CH₂)—CO⁻₂, is reported and the systematic structural variations among 19 crystallographic occurrences of H₃Pep, H₂Pep⁻, HPep²⁻ and Pep³⁻ species, which are important phosphate donors in the ATP cycle of bioenergetics, are reviewed. Tris(cyclohexylammonium) phosphoenolpyruvate monohydrate, (C₆H₁₁NH₃⁺)₃.[O₃POC(CH₂)CO₂]³⁻.H₂O, M_r = 483.6, m.p. 418–420 K; T = 296 (1) K; orthorhombic, P2₁2₁2₁; a = 16.7042 (5), b = 24.4881 (6), c = 6.38910 (10) Å; V = 2613.49 (11) ų, Z = 4, D_x = 1.23, D_m = 1.22 mg mm⁻³, μ = 0.14 mm⁻¹ for λ(MoKα) = 0.7107 Å; F = 1056 e; R(|F|) = 0.0608 for 6056 hkl and hk data with (sin θ)/λ ≤ 0.65 Å⁻¹.