The molecular structures of phthalocyaninatozinc (HPc-Zn) and hexadecafluorophthalocyaninatozinc (FPc-Zn) are determined using the gas electron diffraction (GED) method and high-level density functional theory (DFT) quantum chemical calculations. Calculations at the B3LYP/6-311++G** level indicate that the equilibrium structures of HPc-Zn and FPc-Zn have D-4h symmetry and yield structural parameters in good agreement with those obtained by GED at 480 and 523 degrees C respectively. The calculated force fields indicate that both molecules are flexible. Normal coordinate calculations on HPc-Zn yield five vibrational frequencies (one degenerate) in the range 22-100 cm(-1), and ten vibrational frequencies ranging from 13 to 100 cm(-1) (three degenerate) for FPc-Zn. The high-level force field calculations confirm most of the previous vibrational assignments, and some new ones are suggested. The out-of-plane vibration of the Zn atom in HPc-Zn was studied in detail optimizing models in which the distance from the Zn atom to the two symmetry equivalent diagonally opposed N atoms (h) was fixed. The calculations indicate that the vibrationally activated vertically displacement of the Zn atom is accompanied by distortion of the ligand from D-4h to C-2 nu symmetry. The average height, h, at the temperature of the GED experiment was calculated to be 14.5 pm. Small structural changes indicate that a full F substitution on the benzo-subunits do not significantly alter the geometry, however there are indications that the benzo-subunits may shrink slightly with perfluorination.