The structure of silyl cyclopentadienes

Calculations have been made in the MNDO approximation of the structures and energies of three isomeric forms of (η¹-C₅H₅)SiR₃ (R = H, Me) and of (η⁵-C₅H₅)SiR₃, together with potential energy curves for the folding of the C₅ ring in 5-R₃SiC₅H₅; all the η¹ species have planar C₅rings at equilibrium. In addition (1,2) and (1,3) shift mechanisms have been investigated for migration of both SiH₃ and hydrogen in (η¹-C₅H₅)SiH₃: the lowest energy pathway in each case is the (1,2) shift mechanism; structures and energies of the transition states are reported.