Metal atom dynamics of phthalocyanin tin complexes: SnPc and SnPc2

High purity samples of SnPc and SnPc2 (Pc = phthalocyanin, C32H16N82−) have been examined by temperature-dependent 119Sn Mössbauer effect (ME) spectroscopy in order to elucidate the metal atom dynamics over the temperature range 94 < T < 301 K. Contrary to earlier reported data, the temperature-dependence of the recoil-free fraction, f, of the Sn atom is distinctly different for the two structures, and the root-mean-square-amplitude-of-vibration has been determined for the two Sn atom sites. The metal atom motion in SnPc is essentially isotropic over the above temperature range with respect to the symmetry axis involving the Pc ligand, the metal atom, and the lone pair of electrons.