Electronic and Steric Influences of Pendant Amine Groups on the Protonation of Molybdenum Bis(dinitrogen) Complexes
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https://figshare.com/articles/dataset/Electronic_and_Steric_Influences_of_Pendant_Amine_Groups_on_the_Protonation_of_Molybdenum_Bis_dinitrogen_Complexes/2207902
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资源简介：
The synthesis of a series of PEtPNRR′ (PEtPNRR′ = Et2PCH2CH2P(CH2NRR′)2, R = H, R′
= Ph or 2,4-difluorophenyl; R = R′ = Ph or iPr) diphosphine ligands containing mono- and disubstituted
pendant amine groups and the preparation of their corresponding molybdenum
bis(dinitrogen) complexes trans-Mo(N2)2(PMePh2)2(PEtPNRR′) is described. In situ IR and
multinuclear NMR spectroscopic studies monitoring the stepwise addition
of triflic acid (HOTf) to trans-Mo(N2)2(PMePh2)2(PEtPNRR′) complexes in tetrahydrofuran
at −40 °C show that the electronic and steric properties
of the R and R′ groups of the pendant amines influence whether
the complexes are protonated at Mo, a pendant amine, a coordinated
N2 ligand, or a combination of these sites. For example,
complexes containing monoaryl-substituted pendant amines are protonated
at Mo and the pendant amine site to generate mono- and dicationic
Mo–H species. Protonation of the complex containing less basic
diphenyl-substituted pendant amines exclusively generates a monocationic
hydrazido (Mo(NNH2)) product, indicating preferential protonation
of an N2 ligand. Addition of HOTf to the complex featuring
more basic diisopropyl amines primarily produces a monocationic product
protonated at a pendant amine site, as well as a trace amount of dicationic
Mo(NNH2) product that is additionally protonated at a pendant
amine site. In addition, trans-Mo(N2)2(PMePh2)2(depe) (depe =
Et2PCH2CH2PEt2) was synthesized
to serve as a counterpart lacking pendant amines. Treatment of this
complex with HOTf generated a monocationic Mo(NNH2) product.
Protonolysis experiments conducted on several complexes in this study
afforded trace amounts of NH4+. Computational
analysis of trans-Mo(N2)2(PMePh2)2(PEtPNRR′) complexes provides further insight into the proton affinity
values of the metal center, N2 ligand, and pendant amine
sites to rationalize differences in their reactivity profiles.
创建时间：
2016-02-15
