N<sub>2</sub> Provides Insight into the Mechanism of H−C(sp<sup>3</sup>) Bond Cleavage

Walstrom, Amy; Pink, Maren; Tsvetkov, Nikolay P.; Fan, Hongjun; Ingleson, Michael J.; Caulton, Kenneth G.

doi:10.1021/ja0547580

Cited by 36 publications

(35 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This reaction bears some similarity to that of N 2 with (PNP)Ru(OTf), OTf = O 3 SCF 3 , which triggers H-C bond heterolysis to give {[PN(H)P*]RuN 2 }OTf, where the triflate hydrogen bonds to the NH proton, instead of binding to the metal (cf. iodide on Os here in 8); [16] the difference in products here is that Ru is five coordinate, while Os is six coordinate.…”

Section: Synthesis and Reactivity Of [(Pnp)os(n 2 )I]mentioning

confidence: 99%

Redox and Lewis Acid Reactivity of Unsaturated Os^II

et al. 2010

Self Cite

View full text Add to dashboard Cite

A synthesis of [(PNP)OsI] {PNP = (tBu2PCH2SiMe2)2N} permits evaluation of its reactivity, both Lewis acidity and reducing power (i.e., ability to be oxidized). It binds two molecules of PhCN, into trans sites, but only one of ethylene, and, upon binding of one N2, there is heterolytic splitting of one tBu C–H bond to put the proton on amide N and the carbon on Os, leaving divalent metal in [{PN(H)P*}Os(N2)(I)]. Two moles of H2 add, forming [{PN(H)P}OsH(H2)I], via H–H bond heterolysis. Thermolysis of [(PNP)OsI] gives the product of adding a tBu methyl C–H bond across the Os/N bond, and also net dehydrogenation of this intermediate, forming a carbene complex; the released H2 forms [(PNP)OsH2I], and the chemistry of [(PNP)Os] hydridohalides is described. Reaction with O2 occurs with no detectable intermediate, to completely split the O=O bond, and form trans‐[(PNP)Os(O)2I], a product of four electron redox change. Attempted two electron oxidation by oxygen atom transfer with pyridine N‐oxide or Me3NO or N2O surprisingly effect transposition of N from its silyl substituents onto the metal, and replace N by O, forming a nitride complex of a bis(silyl ether, phosphane) chelate whose oxygen fails to bind to Os. The product is thus four‐coordinate, tetrahedral [(POP)Os(N)I], with an Os/N triple bond.

show abstract

Section: Synthesis and Reactivity Of [(Pnp)os(n 2 )I]mentioning

confidence: 99%

Redox and Lewis Acid Reactivity of Unsaturated Os^II

et al. 2010

Self Cite

View full text Add to dashboard Cite

show abstract

“…With ruthenium, 31 independent observation shows that the formation constant for (PNP)RuCl(N 2 ) is low so that this adduct can only be observed by NMR at low temperature and does not detectably attack the t Bu group. In contrast, for the fourcoordinate, paramagnetic (PNP)Ru(OTf) analog, N 2 causes a rapid reaction with displacement of triflate from the coordination sphere and heterolytic (Scheme 3) splitting of the H-C bond of one t Bu methyl group.…”

Section: Comparison To Rutheniummentioning

confidence: 99%

“…Coupling constants are given in Hz. 31 P NMR spectra are referenced to external standards of H 3 PO 4 . NMR spectra were recorded with a Varian Unity INOVA instrument (400 MHz 1 H; 162 MHz 31 P).…”

Section: Experimental General Considerationsmentioning

confidence: 99%

An evaluation of monovalent osmium supported by the PNP ligand environment

2011

Self Cite

View full text Add to dashboard Cite

Nitrogen is essential to reaction of (PNP)OsI (PNP is N(SiMe(2)CH(2)P(t)Bu(2))(2)) and Mg powder in THF, to give equimolar (PNP)OsH(N(2)) and hydrido carbene [((t)Bu(2)PCH(2)SiMe(2))N(SiMe(2)CH(2)P(t)Bu(CMe(2)CH)]OsH. This reaction is attributed to H(2) evolution from solid magnesium, rather than high energy H atom transfer between molecules, but relies also on the strong π-basicity of Os in favoring α-H migration from the metallated (t)Bu group on Os to form the second product, the hydrido carbene species. The path to two different products begins because the simple N(2) adduct of (PNP)OsI undergoes spontaneous heterolytic H-C splitting of the (t)Bu methyl group, to produce a secondary amine intermediate [((t)Bu(2)PCH(2)SiMe(2))N(H)(SiMe(2)CH(2)P(t)Bu(CMe(2)CH(2))]OsI(N(2)) which can then be dehydrohalogenated by Mg. The analogous reaction for (PNP)RuCl shows production of only (PNP)RuH(N(2)), with none of the hydride carbene dehydrogenation product. Comparative (Ru vs. Os) DFT calculations reveal the reaction steps where the Os analog is much more exothermic, accounting for certain reaction selectivities.

show abstract

“…Since spin density on oxo leaves that ligand oxidized (i.e., less than an octet), this oxyl character helps to define how low a value of q in an MO q+ moiety will still support such oxidation of an "oxo" ligand above its typical charge of 2−. Recent work with the PNP −1 ligand on other metals has suggested the reactivity of (PNP)RhO might not be localized at the unusual oxo ligand, 6,7 but may involve the Rh/O bond and may also include both spin delocalization and even new bond formation to the PNP nitrogen. We report here on the reaction of (PNP)RhO with seemingly the simplest of reagents, H 2 , as well as with simple Lewis bases and with CO or CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Reactivity of the terminal oxo species ((tBu2PCH2SiMe2)2N)RhO

et al. 2013

Self Cite

View full text Add to dashboard Cite

Reactivity of the 4-coordinate molecule (PNP)RhO (PNP is ((t)Bu2PCH2SiMe2)2N) towards CO proceeds stepwise, first forming an η(2)-CO2 complex, by a mechanism which involves a preliminary adduct of CO on Rh, then a second CO displaces CO2. Reaction of the oxo complex with CO2 occurs in time of mixing even at low temperature to form (PNP)Rh(η(2)-CO3), with no intermediate detectable. DFT calculations indicate an initial bond formation between the oxo center and the CO2 carbon. Reaction of (PNP)RhO with H2 occurs only at a 1 : 2 molar stoichiometry, to ultimately form (PNP)Rh(H)2 and free H2O. No intermediate reaches detectable population even at -60 °C, but DFT mapping of various possible mechanisms on the singlet energy surface shows that the nearly equi-energetic (PNP)Rh(H2O) and (PNP)RhH(OH) are formed, but only the latter readily adds the second molecule of H2 to proceed to the observed products; these reactions thus both involve heterolytic splitting of H2.

show abstract

N₂ Provides Insight into the Mechanism of H−C(sp³) Bond Cleavage

Cited by 36 publications

References 20 publications

Redox and Lewis Acid Reactivity of Unsaturated Os^II

Redox and Lewis Acid Reactivity of Unsaturated Os^II

An evaluation of monovalent osmium supported by the PNP ligand environment

Reactivity of the terminal oxo species ((tBu2PCH2SiMe2)2N)RhO

Contact Info

Product

Resources

About

N2 Provides Insight into the Mechanism of H−C(sp3) Bond Cleavage

Cited by 36 publications

References 20 publications

Redox and Lewis Acid Reactivity of Unsaturated OsII

Redox and Lewis Acid Reactivity of Unsaturated OsII

An evaluation of monovalent osmium supported by the PNP ligand environment

Reactivity of the terminal oxo species ((tBu2PCH2SiMe2)2N)RhO

Contact Info

Product

Resources

About

N₂ Provides Insight into the Mechanism of H−C(sp³) Bond Cleavage

Redox and Lewis Acid Reactivity of Unsaturated Os^II

Redox and Lewis Acid Reactivity of Unsaturated Os^II