Ferrocene, theoretical studies

However, more quantitative molecular orbital treatments still leave scope for improvement, and in particular a systematic treatment of the whole metallocene series, rather than of isolated members such as ferrocene, is much to be desired. Moreover, theoretical studies have generally neglected the bis-arene and mixed sandwich series, and in both cases such treatments would be of value in indicating the extent to which the mainly metal n level is or is not less anti-bonding than in the metallocenes. In this connection it is interesting to note that in the (Ch) Cr(Cp)- anion the mainly metal n dxz, dyz ) level may still lie relatively high since esr measurements 1 78) indicate the odd electron to... 

Theoretical studies by E. Ruch (173-177) proved the correctness of this concept of the bonding, with which the retention of the aromatic character of the ring is in harmony. The nature of the bonding in the dicyclopentadienyl metal compounds was discussed by him in terms of molecular and equivalent orbitals, and on the basis of calculated overlap integrals for ferrocene an energy-level diagram was suggested which... 

Against this view are comprehensive theoretical studies which put only a single covalent dr-Pr bond between the metal and the ring in all the transition metal compounds ( 3, 26, 32, 119, 131). On this basis, ferrocene, for example, should show only a closed 3d shell. Four -electrons would then remain in the rings, which could be considered as radicals, without taking part in the bonding. 

This interaction between Fc and IL ions has been theoretically studied by Yang et al. [50]. According to their MEP predictions, the possible interactions of ferrocene with 1,3-dimethylimidazolium tetrafluoroborate ([Cimim][BF4], used as an IL model system) are shown in Figs. 3.5 and 3.6. In Fig. 3.5, it is possible to observe that the IL cation binds to Fc both on the top and from the side. Meanwhile, the IL anion is only able to interact with Fc from the side (Fig. 3.6). 

Organometallic chemistry was greatly stimulated by the fortuitous discovery of ferrocene, (f/s-H5C5)2Fe (2) (/). The recognition and explanation of the remarkable structural and bond theoretical properties of ferrocene by Fischer (2), Wilkinson and Woodward (3a,b,4), and Dunitz (5) established the study of direct metal-carbon bonds as an independent disci-... 

Electron-diffraction data in the gas phase [43] suggest that ferrocene prefers to adapt an eclipsed conformation, with an internal rotational barrier of 0.9 0.3 kcal/mol. The calculated barrier derived from the vibrational frequency of the internal rotational mode is 0.72 kcal/mol [44]. Our LDA/NL calculation finds the eclipsed conformation to be the most stable, with a calculated rotational barrier of 0.69 kcal/mol, in good agreement with experiment. The structure of ferrocene has been studied by several theoretical methods. Our optimized geometrical parameters are similar to those that had been obtained previously by Fan and Ziegler [25] employing the same 1.DA/NL scheme (Table 8). The LDA/NL geometry represents a better fit to experiment than... 

Although the bonding in the proposed ferrocene isomer (Tj -CaHtlfTj -CgHelFe has been studied theoretically, synthesis of this molecule has not been reported (C. M. Brett, B. E. Bursten, Polyhedron, 2004, 23, 2993). For this molecule ... 

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