Deprotonation of [(CO) 2 RReNH(CH 3 )CH 2 CH 2 (η 5 -C 5 H 4 )] + X - (R = CO 2 Me, CO 2 Et; X = Br) followed by heating under a CO atmosphere yields the corresponding CO insertion compound (CO) 2 RReC( O)N(CH 3 )CH 2 CH 2 (η 5 -C 5 H 4 ). An anologous insertion reaction proceeds more rapidly for the complexes [(CO) 2 XReNH(CH 3 )CH 2 CH 2 (η 5 -C 5 H 4 )] + Y - (X = Br, I, PhS, and PhSe) in which X is a strong electron-withdrawing group. Without ...