Conformational analysis of diamagnetic tris-ethylenediamine complexes by proton magnetic resonance. Spectra of tris(ethylenediamine) rhodium(III)

Sudmeier, James L.; Blackmer, Gary L.

doi:10.1021/ic50103a036

Cited by 23 publications

(14 citation statements)

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“…In the 1970's NMR spectroscopy has been applied to the conformational analysis of tris(ethylenediamine) [75][76][77][78] .…”

Section: Vibrational Analysismentioning

confidence: 99%

“…In the 1970's NMR spectroscopy has been applied to the conformational analysis of tris(ethylenediamine). [75][76][77][78] Beattie showed 77 that in aqueous solutions the ligands undergo an interconversion between the l and d conformations; in the L configuration, the d conformation was predicted to be more stable than the l conformation. But, due to statistical entropy effects, the most stable and most abundant species is expected to be L(ldd).…”

Section: Vibrational Analysismentioning

confidence: 99%

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Where does the Raman optical activity of [Rh(en)₃]³⁺come from? Insight from a combined experimental and theoretical approach

Humbert-Droz

Oulevey

Daku

et al. 2014

Phys. Chem. Chem. Phys.

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Backscattered Raman optical activity (ROA) spectra are measured for Δ-and Λ-tris-(ethylenediamine)rhodium( chloride in aqueous solution. In addition, the spectra of the four possible conformers in the Λ configuration are investigated by ab initio calculations. The Λ() conformer is in best agreement with experimental spectra and examined in more details. The two most stable conformers according to the calculations are not compatible with the experimental ROA spectrum. Insights into the origin of observed band intensities are obtained by means of group coupling matrices. The influence of the first solvation shell is explored via an ab initio molecular dynamics simulation. Taking explicit solvent molecules into account further improves the agreement between calculation and experiment. Analysis of selected normal modes using group coupling matrices shows that solvent molecules lead to normal mode rotation and thus contribute to the ROA intensity, whereas the contribution of the Rh can be neglected.

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“…In the 1970's NMR spectroscopy has been applied to the conformational analysis of tris(ethylenediamine) [75][76][77][78] .…”

Section: Vibrational Analysismentioning

confidence: 99%

Section: Vibrational Analysismentioning

confidence: 99%

Where does the Raman optical activity of [Rh(en)₃]³⁺come from? Insight from a combined experimental and theoretical approach

Humbert-Droz

Oulevey

Daku

et al. 2014

Phys. Chem. Chem. Phys.

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“…5,6 The focus, however, has not been solely on the cobalt(III) salt. [7][8][9][10][11][12][13][14][15] In general, the three achiral ethylene diamine (en) ligands can coordinate to the metal center in two different ways to yield either the D or L configurations of the complex, which can often be optically resolved. Furthermore, each en ligand can adopt two chiral conformations referred to as the land d-form with the NCCN torsional angle either being negative or positive.…”

Section: Introductionmentioning

confidence: 99%

Effects of electron configuration and coordination number on the vibrational circular dichroism spectra of metal complexes of trans-1,2-diaminocyclohexane

Merten

Hiller

2012

Phys. Chem. Chem. Phys.

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Transition metal complexes of ethylenediamine have attracted significant interest as prototype systems for a range of studies related to their chiroptical properties. In order to better elucidate the effects of different central metal ions and also different coordination numbers on the vibrational circular dichroism (VCD) spectra, trans-1,2-diamino cyclohexane (chxn) was chosen as the chiral ligands in the current report. In this case the conformation of the diamino ligand is predetermined by its absolute configuration and the transition from the λ- to the δ-form that can occur in the case of ethylenediamine is no longer possible. The fingerprint region of the vibrational absorption and VCD spectra of three transition metal complexes of chxn have been analysed in detail. For the tris chelate complexes Ni(chxn)(3)(2+) and Cu(chxn)(3)(2+), selective enhancement of some VCD bands in the otherwise almost identical spectra has been observed and explained in terms of a ring current mechanism and of a different number of unpaired electrons of the metal centers. The comparison of the VCD spectra of Cu(chxn)(3)(2+) and Cu(chxn)(2)(2+) reveals the effects of coordination number that manifest as an inversion of the strong bisignate VCD pattern of the NH(2) scissor vibrational modes. This leads to the conclusion that this region can be used to extract information about the ligand environment and the chirality of the metal center.

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“…9,23,56 This indicates the likelihood of a rapid interconversion between the conformers in solution at ambient temperatures, as confirmed by NMR studies. 1,57,58 We note that the Co complex crystallizes as the lel 3 conformer. 59 The experimental and theoretical LF transition ECD spectra for lel 3 -Δ-A are shown in Figure 2.…”

Section: Resultsmentioning

confidence: 78%

Theoretical study of the Raman optical activity spectra of with M = Co, Rh

2020

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Vibrational Raman optical activity (ROA) spectra were calculated under off-resonance, near-resonance and at-resonance conditions for [Co(en) 3 ] 3+ (A), and under off-resonance conditions for [Rh(en) 3 ] 3+ (B), using a new driver software for calculating the ROA intensities from complex (damped) time-dependent linear response Kohn-Sham theory. The off-resonance spectra of A and B show many similarities. At an incident laser wavelength of 532 nm, used in commercial ROA spectrometers, the spectrum of A is enhanced by near-resonance with the ligand-field transitions of the complex. The near-resonance spectrum exhibits many qualitative differences compared to the off-resonance case, but it remains bi-signate. Even under full resonance with the ligand-field electronic transitions, the ROA spectrum of A remains bi-signate when the electronic transitions are broadened such as to yield absorption line widths that are comparable to those in the experimental UV-vis absorption and electronic circular dichroism spectra.

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Conformational analysis of diamagnetic tris-ethylenediamine complexes by proton magnetic resonance. Spectra of tris(ethylenediamine) rhodium(III)

Cited by 23 publications

References 1 publication

Where does the Raman optical activity of [Rh(en)₃]³⁺come from? Insight from a combined experimental and theoretical approach

Where does the Raman optical activity of [Rh(en)₃]³⁺come from? Insight from a combined experimental and theoretical approach

Effects of electron configuration and coordination number on the vibrational circular dichroism spectra of metal complexes of trans-1,2-diaminocyclohexane

Theoretical study of the Raman optical activity spectra of with M = Co, Rh

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Conformational analysis of diamagnetic tris-ethylenediamine complexes by proton magnetic resonance. Spectra of tris(ethylenediamine) rhodium(III)

Cited by 23 publications

References 1 publication

Where does the Raman optical activity of [Rh(en)3]3+come from? Insight from a combined experimental and theoretical approach

Where does the Raman optical activity of [Rh(en)3]3+come from? Insight from a combined experimental and theoretical approach

Effects of electron configuration and coordination number on the vibrational circular dichroism spectra of metal complexes of trans-1,2-diaminocyclohexane

Theoretical study of the Raman optical activity spectra of with M = Co, Rh

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Where does the Raman optical activity of [Rh(en)₃]³⁺come from? Insight from a combined experimental and theoretical approach

Where does the Raman optical activity of [Rh(en)₃]³⁺come from? Insight from a combined experimental and theoretical approach