An Unusual Equilibrium Chlorine Atom Transfer Process and Its Potential for Assessment of Steric Pressure by Bulky Aryls

Abstract

An unusually facile intermolecular chlorine atom transfer process has been discovered between the phospha-Wittig reagents ArP=PMe3 and ArPCl2 (Ar is a sterically hindered aryl group). The atom transfer process is catalyzed by added PMe3. A mechanism is forwarded that is based upon a Me3P/Me3PCl2 couple that allows shuttling of chlorine atoms between ArP groups. This unique transfer process is exploited to evaluate the steric properties of aryl groups via an equilibrium process.

2,6-Di(4-t-butylphenyl)phenyl-group 13 organometallic compounds

“…Investigation of the 2,6-di(4-t-butylphenyl)phenyl ligand was undertaken in an effort to gain further insight into the significance of substitution at the ortho position of the outer phenyl rings, or the lack thereof, when employing sterically encumbered m-terphenyl-based ligands [8]. It has been shown that this ligand has the tendency for facile intramolecular C-H bond activation of the ortho position of the outer phenyl ring, which may serve as a mechanism to form an in situ generated bidentate ligand that provides robust steric protection for the metal center [9].…”

Multiple‐Bond Metathesis Mediated by Sterically Pressured Uranium Complexes

“…Sterically tailored, highly reactive transition-metal complexes achieve a wide variety of small-molecule activation and atom-transfer chemistry very successfully. [2][3][4][5][6] The strategy of applying steric pressure, however, is not always sufficient to achieve certain desired reactivities. The most recent class of transition-metal-based nitrogen-transfer reagents (aziridination catalysts), for example, takes advantage of high-valent transition-metal nitrido complexes that readily transfer the imidoacyl entity to olefins upon activation with trifluoroacetic acid anhydride (TFAA).…”

Steric Coordination Control of Interchain Interactions in Conducting Metallopolymers

“…[62] We recently reported a small molecule model comprising a metal-binding site that fulfills these criteria (M1, Figure 2). [58] M1 enforces a 1:1 metal/bipy ratio that also has dissociation constants similar to those for 2,2 0 -bipyridine in THF, demonstrating that the presence of mesityl groups does not significantly alter the metalbinding strength.…”