Experimental and Theoretical Study of the Encapsulation of a Linear Oligo(ferrocenylsilane) Trimer with b-cyclodextrin.

Abstract

An inclusion compound comprising β-cyclodextrin (β-CD) and the trimetallic oligo(ferrocenylsilane) FcSiMe2[(η5-C5H4)Fe(η5-C5H4SiMe2)]Fc [Fc = (η5-C5H5)Fe(η5-C5H4)] has been prepared and characterised in the solid state by elemental analysis, powder X-ray diffraction, thermogravimetric analysis and magic angle spinning NMR spectroscopy (13C, 29Si). The results are consistent with the formation of a 2:1 (host-to-guest) inclusion complex. Ab initio calculations were carried out in order to investigate the possible inclusion geometries. The best host–guest fit was obtained for a tilted geometry of the ferrocene fragment relative to the β-CD axis ( = 29°) with a 140-pm inclusion of the corresponding Fe centre below the plane of the rim. The structure of the organometallic trimer allows its inclusion interaction with a second β-CD host, leading to the 2:1 stoichiometry.

J.A. Fernandes, S. Lima, S.S. Braga,M. Pillinger, J.E. Rodríguez-Borges, Paulo Ribeiro-Claro, J.J.C. Teixeira-Dias, I.S. Gonçalves