Molecular mechanics force fields for linear metallocenes

A Simple New Structural Force Field for the Computation of Linear Metallocenes

“…Here, the structural plots help to visualize the con- computed using an alternative approach (δ ϭ 23.7°). [12] Thus, structural features, including those of the ring rotation, are well reproduced by our new force field, while Supporting Information dynamic properties are not. The approach used here allows…”

“…[22] Parameters not previously published [23] are given in Table 3 (the atom-type labels are defined in Figure 2; starting values for the parameters were taken from vibrational spectroscopic data and/or from other force fields [6] [12] and refined by fitting to the set of test structures). The conformational space was searched with a cartesian stochastic search routine ("random kick" Monte Carlo method), which has recently been implemented in MOMEC and validated for a series of (amine)cobalt(III) com- Figure 2.…”

“…In addition, it should be on the Cp rings. [12] This model allowed accurate computation of the structures and vibrational spectra of linear meeasy to extend the model to other classes of organometallic compounds, such as cyclopentadienylϪmetal compounds tallocene compounds. [12] The only obvious disadvantage is that this method needs a specific algorithm, which is not with various other donors, transition-metal compounds generally available in commercial programs.…”

“…[12] This model allowed accurate computation of the structures and vibrational spectra of linear meeasy to extend the model to other classes of organometallic compounds, such as cyclopentadienylϪmetal compounds tallocene compounds. [12] The only obvious disadvantage is that this method needs a specific algorithm, which is not with various other donors, transition-metal compounds generally available in commercial programs. As yet, it has only been used for linear metallocenes and has not been [a] Anorganisch-Chemisches Institut, Universität Heidelberg, extended to other similar problems such as the computation [28] model has been widely used for transition-metal coordi-(MeCp) 2 ENTRY'NOYSEZ [30] (Me 4 Cp) 2 JAROUB [31] nation compounds [6,8,22,23] and is implemented in most (Me 5 Cp) 2 FODWEZH [32] commercially available programs.…”

Geometry optimization of metal complexes using natural internal coordinates: Representation of skeletal degrees of freedom

“…The introduction of such a reference point that does not increase the number of degrees of freedom was first addressed by Doman et al in connection with molecular mechanics type optimization of metallocenes. 11 These authors suggested the elimination of the forces on the dummy atom by distributing them to real atoms. Kaupp and Schleyer also used the centroid approach to determine the energy profile of bent metallocenes as a function of the skeletal bending angle.…”