Physicochemical Characterization of New Octamethylferrocenylmethylenemalononitrile by Complementary Methods:UV-Visible Solvatochromism,Moessbauer Spectroscopy,Differential Scanning Calorimetry,and X-ray Structure Determination

摘要

(Octamethylferrocenylmethylene)malononitrile (dicyanoethenyl-octamethylferrocene)was synthesized by condensation of octamethylferrocene carbaldehyde with malononitrile.The visible positive solvatochromism of the new compound was studied in 33 solvents and discussed in terms of Kamlet-Taft's pi and a scales.Temperature-dependent Moessbauer Spectroscopy using a ~(57)Fe-enriched sample suggests that the onset of ring rotation of the tetramethyl Cp ring was not accompanied by a significant librational motion of the ring.The quadrupole splitting parameter went through a maximum at approx220 K suggesting a phase change in the solid.Differential scanning calorimetry showed two endotherms at 228 and 236 K.Single crystal X-ray structure determinations at different temperatures showed two kinds of disorder at 243 K,only one of which remained at 183 K.A reversible change of disorder was observed at 213 K.