870854-21-0Relevant articles and documents
Alkene Insertions into a Ru-PR2 Bond
Burton, Krista M. E.,Pantazis, Dimitrios A.,Belli, Roman G.,McDonald, Robert,Rosenberg, Lisa
, p. 3970 - 3980 (2016/12/22)
An unusually broad series of discrete alkene insertion reactions has provided the opportunity to examine the mechanism(s) of this fundamental carbon-heteroatom bond-forming process. Ethylene, electron-rich and electron-poor (activated) alkenes all react with the Ru-P double bond in Ru(η5-indenyl)(PCy2)(PPh3) to form κ2-ruthenaphosphacyclobutanes. Thermal decomposition of these metallacycles in solution, via alkene deinsertion and β-hydride elimination, is particularly favored for electron-rich alkenes, and hydride-containing decomposition products are implicit intermediates in the observed isomerization of 1-hexene. Kinetic studies, including a Hammett analysis of the insertion reactions of para-substituted styrenes, suggest that two distinct inner-sphere pathways operate for the insertion of electron-rich versus activated alkenes. DFT analyses have identified one pathway involving simple cycloaddition via a four-centered transition state and another that proceeds through an η2-alkene intermediate. Such an intermediate was observed spectroscopically during formation of the ethylene metallacycle, but not for substituted alkenes. We propose that “pre-polarized”, activated alkenes participate in direct cycloaddition, while rate-determining η2-adduct formation is necessary for the activation of electron-rich alkenes toward migratory insertion into the Ru-P bond.
A highly reactive ruthenium phosphide complex exhibiting Ru-P π-bonding
Derrah, Eric J.,Pantazis, Dimitrios A.,McDonald, Robert,Rosenberg, Lisa
, p. 1473 - 1482 (2008/10/09)
Multiple bonding in the terminal phosphido complex [Ru(PCy 2)(η5-indenyl)(PPh3)J (2a) is clearly demonstrated by solution, solid-state, and computational studies. Reactions of this dark blue, half-sandwich complex with CO, MeI, HNEt3Cl, HCl, NH4PF6, H2, and Et3SiH demonstrate an unusual range of behavior resulting from combined coordinative unsaturation at Ru, high nucleophilicity/basicity of the phosphido P, and π-character of the Ru-P interaction. The terminal, π-bound phosphido structure is general for a range of PR2 species (R = Pri (2b), Ph (2c), Tolp (2d)). The very reactive diarylphosphido analogues 2c,d have been observed spectroscopically at low temperatures and can be trapped quantitatively as their CO adducts, [Ru(PAr2)(η5- indenyl)(CO)(PPh3)] (3c,d), in which the Ru-P bond order is reduced to 1. Complex 2a and its analogue [Ru(PPri2) (η5-indenyl)(PPh3)] (2b) are consistently isolated with ～15% of their structural isomers, the ruthenium hydrido phosphaalkenes 9a,b, resulting from an apparent 1,2-H shift.
Electronic control of conformation in mixed-phosphine complexes of the ruthenium η5-indenyl fragment
Derrah, Eric J.,Marlinga, Jazmin C.,Mitra, Debbie,Friesen, Dawn M.,Hall, Shaun A.,McDonald, Robert,Rosenberg, Lisa
, p. 5817 - 5827 (2008/10/09)
The solid-state conformations of a series of new, mixed secondary and tertiary phosphine complexes of the general formula [Ru(η5- indenyl)Cl(PPh3)(HPR2)] have been shown to persist in solution, largely because of the electronic requirements of the ancillary η5-indenyl ligand in these complexes. The crystallographically observed conformations, with the indenyl benzo ring lying anti to the secondary phosphine across the Ru-η5-indenyl bond, were diagnosed in solution from chemical shift differences for PPh3 signals in the low-temperature-limiting 1H and 13C NMR spectra. These conformations were tuned by varying the relative trans influences of the different piano-stool legs, in particular through preparation of the analogous hydrido complexes [Ru(η5-indenyl)H(PPh3)(HPR 2)], which resulted in structures with the indenyl benzo ring anti to the hydride ligand. These studies provide evidence for the reasonably strong trans influence of coordinated secondary phosphines relative to PPh3. Implications for the ancillary ligand behavior of secondary phosphines are discussed.
