摘要:
A series of four monomeric and four polymeric ferrocenyl- and octamethylferrocenyl-substituted 1-alkynes, ethynylferrocene (1) [1271-47-2], 2-ethynylphenylferrocene (2) [1292-14-4], [2-[ethynylphen-2-yl]ethen-1-yl]-1',2,2',3,3',4,4',5-octamethylferrocene (3), novel [2-[ethynylphen-2-yl]ethen-1-yl]-1',2,2',3,3',4,4',5-octamethylferricinium hexafluorophosphate (4) and poly(ethynylferrocene) (5) [33410-56-9], poly(2-ethynylphenylferrocene) (6) [205865-61-8], poly([2-[ethynylphen-2-yl]ethen-1-yl]-1',2,2',3,3',4,4',5-octamethylferrocene) (7), and novel poly([2-[ethynylphen-2-yl]ethen-1-yl]-1',2,2',3,3:4,4',5-octamethylferricinium hexafluorophosphate) (8), have been studied by temperature-dependent Fe-57-Mossbauer spectroscopy. The relevant Mossbauer parameters have been determined and are compared with the data obtained for the model compound octamethylferrocene (OMF). The data obtained by Fe-57-Mossbauer spectroscopy reflect a small decrease of s-electron density from the ferrocene moiety to the conjugated backbone, as is demonstrated by the smaller IS of the monomers 1-3 in comparison with the corresponding polymers 5-7. As may be deduced from the temperature dependence of the recoil-free fraction and the calculated Lattice temperatures, the polymers are much 'softer' (within the definitions of Mossbauer spectroscopy) than the corresponding monomers. Finally, an unusual phase transition has been observed in OMF some 80 degreesC below the melting point, which appears to lead to a large, sudden, and unexpected increase in the mean-square-amplitude of vibration of the metal atom in methyl substituted ring systems. This anomalous T-dependence of the recoil-free fraction, which is associated with the presence of the ring methyl groups, is not observed when one (or more) of the ring protons is replaced by a sterically bulky side chain, as in 1-3. (C) 2000 Elsevier Science B.V. All rights reserved.