Dilatation thermique du cyclopentadienyl thallium TlC₅H₅ entre 78 et 295 K

The thermal expansion of cyclopentadienylthallium, TlC₅H₅, was determined in the range 78 to 295 K, using X-ray powder diffractometry. Expansion is very anisotropic: α₁ = 125 ± 12, α₂ = 97 ± 5, α₃ = 0 ± 4 (all 10⁻⁶ K⁻¹). Directions and ratio of the two greatest expansion coefficients: α₁ and α₂, are explained by considering the shortest distances Tl⁺–Tl|⁺ in this ionic structure.