Photoreaction of a mixture of Cp*(CO)3WMe (Cp* = η5-C5Me5) and HSiR2Ar [R 2Ar = Me2Ph, Me2(p-Tol), Me(p-Tol)2, and (p-Tol)2] in the presence of 4-(dimethylamino)pyridine (DMAP) gave DMAP-stabilized aryl(silylene) complexes Cp*(CO)2W(Ar)(= SiR2-DMAP) [la, R = Me, Ar = Ph; lb, R = Me, Ar = p-Tol; lc, R2 = Me(p-Tol), Ar = p-Tol; Id, R = Ar = p-Tol] via 1,2-migration of the aryl group from a silyl ligand to a tungsten center. Thermal reactions of Cp*(CO)2W(DMAP)Me (2) with HSiR2Ar at room temperature also gave la - d, and in all cases the yields were higher than those in the photoreaction. Silylene complexes la - d easily isomerized to arylsilyl complexes Cp*(CO)2- W(DMAP)(SiR2Ar) [3a, R = Me, Ar = Ph; 3b, R = Me, Ar = p-Tol; 3c, R, = Me(p-Tol), Ar = p-Tol; 3d, R = Ar = p-Tol] at 40-55 °C. On the other hand, irradiation of arylsilyl complexes 3a - d reproduced silylene complexes la - d, implying that the 1,2-aryl-migration between tungsten and silicon is reversible. The molecular structures of lc, 2, 3a, and 3d were determined by X-ray crystallography. A kinetic study on the 1,2-aryl-migration in the thermal isomerization from la - d to 3a - d suggests that the rate-determining step involves dissociation of DMAP from la - d.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry