Experimental and Molecular Dynamics Simulation Study of the Sublimation and Vaporization Energetics of Iron Metalocenes. Crystal Structures of Fe(η5-C5H4CH3)2and Fe[(η5-(C5H5)(η5-C5H4CHO)]

Abstract

The standard molar enthalpies of sublimation of ferrocene, 1,1‘-dimethylferrocene, decamethylferrocene, ferrocenecarboxaldehyde and α-methylferrocenemethanol, and the enthalpy of vaporization of N,N-dimethyl(aminomethyl)ferrocene, at 298.15 K, were determined by Calvet-drop microcalorimetry and/or the Knudsen effusion method. The obtained values were used to assess and refine our previously developed force field for metallocenes. The modified force field was able to reproduce theandvalues of the test-set with an accuracy better than 5 kJ·mol^-1, except for decamethylferrocene, in which case the deviation between the calculated and experimentalvalues was 16.1 kJ·mol^-1. The origin of the larger error found in the prediction of the sublimation energetics of decamethylferrocene, and which was also observed in the estimation of structural properties (e.g., density and unit cell dimensions), is discussed. Finally, the crystal structures of Fe(η⁵-C₅H₄CH₃)₂ and Fe[(η⁵-(C₅H₅)(η⁵-C₅H₄CHO)] at 293 and 150 K, respectively, are reported.