Investigation of the Regioselectivity of Alkene Hydrosilylation Catalyzed by Organolanthanide and Group 3 Metallocene Complexes

Abstract

The regioselectivity of monosubstituted alkene hydrosilylation catalyzed by organolanthanide and group 3 organometallic complexes has been studied as a function of catalyst structure. A wide variety of catalyst variations were shown to be compatible with the hydrosilylation process. Several novel complexes were synthesized to widen the scope of this investigation. The results show complexes containing larger lanthanide metal ions and reduced substitution on the cyclopentadienyl ligands produce increased yields of the secondary silane product. Several complexes were identified that are highly selective for primary silane generation.Supporting Information Available: NMR spectra for compounds without reported elemental analyses as well as details of the X-ray stucture determination of 6 and 7 (27 pages). Ordering information is given on any current masthead page.

“Constrained geometry” catalysts of the rare-earth metals for the hydrosilylation of olefins

“…This observation is in accordance with the results obtained by Molander et al in their study of the influence of parameters such as metal radius and ligand sterics on the regioselectivity of 1-decene hydrosilylation by rare-earth metallocenes [7]. They showed that a major condition for the increase in 2,1-regioisomer vs. 1,2-regioisomer was the accessible space at the active site of the catalyst and that the combination of a small metal with a sterically hindered ligand gave complete 1,2-regioselectivity.…”

“…Length of the link. According to the previous studies performed on rare-earth metallocenes in comparison with rare-earth ansa-metallocenes, the presence of a link between the two cyclopentadienyl-moieties has been shown to influence the reactivity and the regioselectivity of the corresponding catalysts significantly by creating a well defined space around the active site [7]. In the case of ''constrained geometry'' catalysts, the length of the link …”

Differences in the cyclometalation reactivity of bisphosphinimine-supported organo-rare earth complexes

“…The organometallic chemistry of trivalent rare earth complexes has found many important applications in the field of catalysis, including the metal-catalyzed hydrophosphonylation of carbonyls, 1 hydrogenation, [2][3][4][5][6][7] the catalytic addition of H-X to unsaturated moieties (e.g. hydroamination, 8-16 hydrosilylation, 10,[16][17][18][19][20] hydrophosphination, [21][22][23][24] hydroboration, 25,26 and hydroalkoxylation [27][28][29][30] ), and especially polymerization chemistry. [31][32][33][34][35][36][37][38][39][40][41][42][43][44] However, compared to research on organotransition-metal species, the study of rare earth complexes remains much less explored.…”

Asymmetric Hydrosilylation of Carbon–Carbon Double Bonds and Related Reactions

“…Asymmetric hydrosilylation of α -substituted styrenes ( 31 ) with phenylsilane by a chiral organolanthanide catalyst ( 32 ) gave the corresponding benzylic tert -alkylsilanes ( 33 ) in high enantiomeric excess (Scheme 9.7 ) [22] . …”