Thioether, Dinitrogen, and Olefin Complexes of (PNP)Rh:  Kinetics and Thermodynamics of Exchange and Oxidative Addition Reactions

A variety of (PNP)Rh−L complexes (where L = organic sulfide or sulfoxide, dinitrogen, or tert-butylethylene) have been synthesized by trapping transient (PNP)Rh (1) in situ. Equilibrium studies established the relative affinity of the (PNP)Rh fragment (1) for various L in the following order (of dec...

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Veröffentlicht in:Organometallics 2007-12, Vol.26 (25), p.6066-6075
Hauptverfasser: Gatard, Sylvain, Guo, Chengyun, Foxman, Bruce M., Ozerov, Oleg V.
Format: Artikel
Sprache:eng
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Zusammenfassung:A variety of (PNP)Rh−L complexes (where L = organic sulfide or sulfoxide, dinitrogen, or tert-butylethylene) have been synthesized by trapping transient (PNP)Rh (1) in situ. Equilibrium studies established the relative affinity of the (PNP)Rh fragment (1) for various L in the following order (of decreasing affinity):  Ph2SO > SBu n 2 > SPhMe > dibenzothiophene > SPh2 > benzothiophene > SPr i 2 > thiophene ≈ SBu t Me > SBu s 2 ≈ H2CCHCMe3 ≫ SBu t 2. Dinitrogen reacted with 1 to yield a mixture of terminal and bridging N2 complexes and was found to bind more strongly than SPr i 2. Reaction of (PNP)Rh(SPr i 2) (10) with PhHal led to the corresponding oxidative addition products (PNP)Rh(Ph)(Hal) (Hal = Cl, 18a; Hal = Br, 18b; Hal = I, 18c). The relative rates of oxidative addition of PhHal to 10 were found to be in the order PhI > PhBr > PhCl. Kinetic studies of the reaction of 10 with PhBr were consistent with the reaction proceeding via reversible dissociation of SPr i 2, followed by irreversible addition of PhBr. Evidence for a similar dissociative mechanism for the conversion of 10 to (PNP)Rh(S(O)Ph2) in a ligand exchange reaction was also discovered. Solid-state structures of [(PNP)Rh]2(N2) (19a) and (PNP)Rh(H2CCHCMe3) (21) were determined using X-ray crystallography. Approximately square-planar geometry about Rh was registered.
ISSN:0276-7333
1520-6041
DOI:10.1021/om700563k