Theoretical studies on the proton affinities of four different series of nano-size diamines and designing strong superbases based on fullerene(C60) molecule

Bayat, Mehdi; Salehzadeh, Sadegh

doi:10.1016/j.theochem.2010.07.015

Cited by 6 publications

(6 citation statements)

References 41 publications

(51 reference statements)

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“…Typical “Proton Sponge” compounds are reluctant to add a second proton. The difference between the first and second proton affinities which we calculated for np(NMe 2 ) 2 is an enormous 127.4 kcal mol –1 , in reasonable agreement with the recently published value of 132.9 kcal mol –1 . It is instructive to compare 3a with np(NSIDM) 2 in this context, since both compounds differ only in their backbone (fc vs np).…”

Section: Results and Discussionsupporting

confidence: 89%

“…The difference between the first and second proton affinities which we calculated for np(NMe 2 ) 2 is an enormous 127.4 kcal mol −1 , in reasonable agreement with the recently published value of 132.9 kcal mol −1 . 44 It is instructive to compare 3a with np(NSIDM) 2 in this context, since both compounds differ only in their backbone (fc vs np). The PA value of 3a is 2 kcal mol −1 higher than that of the "Proton Sponge" np(NSIDM) 2 .…”

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confidence: 99%

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Ferrocene-Based Bis(guanidines): Superbases for Tridentate N,Fe,N-Coordination

et al. 2013

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The condensation of 1,1′-diaminoferrocene (1) with a range of chloroformamidinium salts [(R′RN) 2 CCl]X (2) afforded the corresponding bis(guanidines) [Fe{(η 5 -C 5 H 4 )−NC(NRR′) 2 } 2 ] (3; five examples). The two guanidine units present in 3 are able to chelate a proton or a water molecule. The structures of 3 and of the corresponding hydrates were determined by single-crystal X-ray diffraction. Cyclic voltammetry revealed that the ferrocene moiety of 3 is exceptionally electron rich, with E 1/2 values down to −0.90 V vs the ferrocenium/ ferrocene couple. According to the results of DFT calculations, these bis-(guanidines) are superbases with proton affinities considerably higher than that of the classic "Proton Sponge" 1,8-bis(dimethylamino)naphthalene. Furthermore, they are able to act as tridentate ligands, giving rise to Fe→M dative bonds, as is shown by chelates of the type [PdCl(3-κFe,κ 2 N)] + , which were obtained by reaction of 3 with [PdCl 2 (MeCN) 2 ]. The unusual N,Fe,N-chelating mode leads to exceptionally short Fe−Pd bonds (ca. 2.69 Å) and causes an enormous coordination-induced anodic shift of the half-wave potential of ca. 0.6 V.

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Section: Results and Discussionsupporting

confidence: 89%

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confidence: 99%

Ferrocene-Based Bis(guanidines): Superbases for Tridentate N,Fe,N-Coordination

et al. 2013

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“…Many new classes of nonionic superbases have been designed, and many of them have been prepared during the past decade. Among these are guanidinophosphazenes, − various types of proton sponges, − superbasic guanidine derivatives, ,,− macrocyclic proton chelators, , chiral phosphazenes, ,− quinones, phosphonium ylides, ,, azaphosphatranes, , carbenes, ,,− etc. ,− Theoretical calculations predict that many of these bases are more basic than the most basic experimentally measured compoundP 2 -phosphazene EtP 2 (dma) 5 (dma = dimethylamino; see Chart for its structure; GB = 264 kcal mol –1 ) …”

Section: Introductionmentioning

confidence: 99%

Experimental Basicities of Phosphazene, Guanidinophosphazene, and Proton Sponge Superbases in the Gas Phase and Solution

et al. 2016

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Experimental gas-phase superbasicity scale spanning 20 orders of magnitude and ranging from bicyclic guanidine 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene to triguanidinophosphazenes and P3 phosphazenes is presented together with solution basicity data in acetonitrile and tetrahydrofuran. The most basic compound in the scale-triguanidinophosphazene Et-N═P[N═C(NMe2)2]3-has the highest experimental gas-phase basicity of an organic base ever reported: 273.9 kcal mol(-1). The scale includes besides the higher homologues of classical superbasic phosphazenes and several guanidino-substituted phosphazenes also a number of recently introduced bisphosphazene and bis-guanidino proton sponges. This advancement was made possible by a newly designed Fourier transform ion cyclotron resonance (ICR) mass spectrometry setup with the unique ability to generate and control in the ICR cell sufficient vapor pressures of two delicate compounds having low volatility, which enables determining their basicity difference. The obtained experimental gas-phase and solution basicity data are analyzed in terms of structural and solvent effects and compared with data from theoretical calculations.

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“…DFT-B3LYP and MP2 calculations for diazanaphthalenes give D 2 /D 1 0.5 [25]. DFT calculations for a series of diamines containing hydrocarbon bridges give D 2 /D 1 ∼ 0.8 − 0.9 [26]. For uracil, DFT-B3LYP calculations give a proton affinity of 800-900 kJ/mol depending on the protonation site and the tautomer, and a deprotonation enthalpy of 1350-1450 kJ/mol [27].…”

Section: Model Parameter Values For Specific Moleculesmentioning

confidence: 99%

A diabatic state model for double proton transfer in hydrogen bonded complexes

McKenzie

2014

The Journal of Chemical Physics

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Four diabatic states are used to construct a simple model for double proton transfer in hydrogen bonded complexes. Key parameters in the model are the proton donor-acceptor separation R and the ratio, D 1 /D 2 , between the proton affinity of a donor with one and two protons. Depending on the values of these two parameters the model describes four qualitatively different ground state potential energy surfaces, having zero, one, two, or four saddle points. In the limit D 2 = D 1 the model reduces to two decoupled hydrogen bonds.As R decreases a transition can occur from a concerted to a sequential mechanism for double proton transfer. *

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Theoretical studies on the proton affinities of four different series of nano-size diamines and designing strong superbases based on fullerene(C60) molecule

Cited by 6 publications

References 41 publications

Ferrocene-Based Bis(guanidines): Superbases for Tridentate N,Fe,N-Coordination

Ferrocene-Based Bis(guanidines): Superbases for Tridentate N,Fe,N-Coordination

Experimental Basicities of Phosphazene, Guanidinophosphazene, and Proton Sponge Superbases in the Gas Phase and Solution

A diabatic state model for double proton transfer in hydrogen bonded complexes

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