A theoretical study on (η⁵-C₅H₅)Fe(CO)(PPh₃(C(O) CHMe) anion structure and stereoselectivity

Organometallic systems provide an exceptional tool in the stereoselective synthesis. The source of this selectivity, however, frequently remains a challenging question. In recent years, theoretical studies of mechanisms of organometallic and metalloprotein catalysis have received considerable attention. The density functional theory (DFT) methods have been shown to be very successful in these studies. Their application, however, is still limited by the performance of the present computers. As the result, a new class of methods, which employ quantum mechanical calculations combined with either semiempirical and/or molecular mechanics levels (QM/MM), has been developed. This stimulated development of a number of new semiempirical methods, which can handle metals. We present a comparison of a few of these new methods with the DFT level on the example of the acetyliron. In addition, the DFT calculations are used to shed some light on the mechanism of the stereospecific catalysis by acetyliron.