E−H Bond Activation Reactions (E = H, C, Si, Ge) at Ruthenium: Terminal Phosphides, Silylenes, and Germylenes
Abstract
The placement of a strongly trans-influencing ligand on a ruthenium center opposite an anchoring silyl group of the tetradentate tripodal tris(phosphino)silyl ligand, [SiP^(Ph)_3]^− ([SiP^(Ph)_3]^− = tris(2-(diphenylphosphino)phenyl)silyl), has been explored. Installation of alkyl or terminal phosphide ligands trans to the anchoring silyl group affords the complexes [SiPPh3]RuR (R = Me (2), CH_2Ph (4), PPh_2 (5), P^iPr_2 (6)). Complexes 2, 4, and 5 are thermally unstable. Complexes 2 and 4 decay to the cyclometalated complex [SiP^(Ph)_2P′^(Ph)]Ru (3), whereas complex 5 decays to the cyclometalated phosphine adduct [SiP^(Ph)_2P′^(Ph)]Ru(PHPh_2) (7). Complex 3 is found to effect E−H (E = H, C, Si, Ge) bond activation of substrates such as secondary silanes and germanes to yield the structurally unusual silylene complexes [SiP^(Ph)_3]Ru(H)(SiRR′) (R = R′ = Ph (10a), R = Ph R′ = Me (10b)) and the germylene complex [SiP^(Ph)_3]Ru(H)(GeR_2) (R = Ph) (11) via double E−H activation transformations. Both theory and experiments suggest electrophilic character at the silylene moiety. Reaction of 3 with catecholborane, in contrast to silanes and germanes, results in insertion of the B−H unit into the M−C bond of the cyclometalated species to yield the borate complex [SiP^(Ph)_2P^(Ph)-B(cat)]Ru(μ-H) (14). Complex 3 also reacts with bis(catecholato)diboron to yield a similar complex, [SiP^(Ph)_2P^(C6H3B(cat))-B(cat)]Ru(μ-H) (15), with selective borylation of an ortho C−H bond.
Additional Information
Copyright © 2009 American Chemical Society. Received March 20, 2009. Publication Date (Web): June 16, 2009. This work was supported by the NSF (CHE-0750234). Dr. Jeffrey H. Simpson is acknowledged for assistance with NMR studies. Dr. Peter Müller, Neal Mankad, and Samantha MacMillan are acknowledged for crystallographic assistance, and Paul Oblad is acknowledged for a preliminary reaction study. The NSF is acknowledged for its support of the DCIF at MIT (CHE-9808061 and DBI-9729592). We also acknowledge a reviewer for a helpful suggestion regarding the η3 formulation for complex 4. Supporting Information: X-ray crystallographic data, kinetic data, and NMR spectra for 4, 5, 8, 9, 10b, 12, and 13. This material is available free of charge via the Internet at http://pubs.acs.org.Attached Files
Supplemental Material - Takaokaom900216u_si_001.pdf
Supplemental Material - Takaokaom900216u_si_002.cif
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Additional details
- Eprint ID
- 15525
- Resolver ID
- CaltechAUTHORS:20090901-115356130
- NSF
- CHE-0750234
- NSF
- CHE-9808061
- NSF
- DBI-9729592
- Created
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2009-09-14Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field