3.2 Exhaustive Reaction Path Search Using the SC-AFIR Method . . . . . . . . . . . . . . . . . . . . . . . 70
4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Abstract The computational methods to find the transition states (TSs) are powerful to understand the mechanisms of organometallic reactions. Recently, automatic
and systematic search methods of reaction pathways have attracted attention. Among
them, one of the most successful methods is the artificial force-induced reaction
(AFIR) method. The advantage of the AFIR method is that the reaction pathways can
be explored without the prejudgment of the products as well as the reaction coordinates. In this chapter, the concept and algorithms of the AFIR method are described.
We also introduce the recent AFIR studies about organometallic reactions and show
how the exhaustively gathered TSs contribute to a better understanding of the
reaction mechanism and the origin of the selectivity.
Keywords Artificial force-induced reaction (AFIR) method · Asymmetric catalytic
reaction · Global reaction route mapping (GRRM) · Transition state sampling
1 Introduction
Computational chemistry has contributed to the elucidation of the reaction mechanism of organometallic reactions [1–4]. One of the great advantages of computational chemistry is the ability to calculate the stability and geometry of transition
state (TS). Many quantum chemical calculation softwares are capable of performing
geometry optimization calculations [5], which enable us to obtain the TS along the
path of presumed reaction mechanisms. To provide a reasonable initial structure for
a geometry optimization calculation, however, enough experience is needed. Thus,
computational methodologies to easily obtain TSs for presumed reaction mechanisms have been actively developed. One of the conventional methods is the relaxedscan method (or the coordinate driving method) [6], which repeats energy minimization, while changing the designated coordinate, in the coordinate space orthogonal
to that, and gives the energy maximum point along the obtained potential curve as an
approximate TS structure. Besides this method, various methods have been developed, including double-end methods, which use the structure of product to guide
deciding the search direction [7–14].
Some readers may think that double-end methods could always provide the best
reaction path connecting the start and final points of the reaction. In many organometallic reactions, however, it is not true. In general, there are multiple reaction paths
connecting the given reactant and product. Among the paths, the most kinetically
favorable one is the best reaction path. If there are multiple reaction paths with
58
M. Hatanaka et al.
4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Abstract The computational methods to find the transition states (TSs) are powerful to understand the mechanisms of organometallic reactions. Recently, automatic
and systematic search methods of reaction pathways have attracted attention. Among
them, one of the most successful methods is the artificial force-induced reaction
(AFIR) method. The advantage of the AFIR method is that the reaction pathways can
be explored without the prejudgment of the products as well as the reaction coordinates. In this chapter, the concept and algorithms of the AFIR method are described.
We also introduce the recent AFIR studies about organometallic reactions and show
how the exhaustively gathered TSs contribute to a better understanding of the
reaction mechanism and the origin of the selectivity.
Keywords Artificial force-induced reaction (AFIR) method · Asymmetric catalytic
reaction · Global reaction route mapping (GRRM) · Transition state sampling
1 Introduction
Computational chemistry has contributed to the elucidation of the reaction mechanism of organometallic reactions [1–4]. One of the great advantages of computational chemistry is the ability to calculate the stability and geometry of transition
state (TS). Many quantum chemical calculation softwares are capable of performing
geometry optimization calculations [5], which enable us to obtain the TS along the
path of presumed reaction mechanisms. To provide a reasonable initial structure for
a geometry optimization calculation, however, enough experience is needed. Thus,
computational methodologies to easily obtain TSs for presumed reaction mechanisms have been actively developed. One of the conventional methods is the relaxedscan method (or the coordinate driving method) [6], which repeats energy minimization, while changing the designated coordinate, in the coordinate space orthogonal
to that, and gives the energy maximum point along the obtained potential curve as an
approximate TS structure. Besides this method, various methods have been developed, including double-end methods, which use the structure of product to guide
deciding the search direction [7–14].
Some readers may think that double-end methods could always provide the best
reaction path connecting the start and final points of the reaction. In many organometallic reactions, however, it is not true. In general, there are multiple reaction paths
connecting the given reactant and product. Among the paths, the most kinetically
favorable one is the best reaction path. If there are multiple reaction paths with
58
M. Hatanaka et al.