Disclosing the multi-faceted world of weakly interacting inorganic systems by means of NMR spectroscopy

Rocchigiani, Luca; Macchioni, Alceo

doi:10.1039/c5dt04620c

Cited by 21 publications

(11 citation statements)

References 42 publications

(28 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A lengthening of Fe–N distances suggests the high‐spin configuration of Fe III ion. Neutrality of compound is assured by PF 6 – as counterion, which locates close to the ethylene bridge, consistently with what generally found in solution for other complexes by means of 19 F, 1 H‐HOESY NMR studies . The two benzyl groups attached at N2 and N4 extend axially in agreement with a non‐crystallographic C2 symmetry of the molecule, leaving unrestrained the equatorial plane.…”

Section: Resultssupporting

confidence: 82%

Iron(III) Complexes with Cross‐Bridged Cyclams: Synthesis and Use in Alcohol and Water Oxidation Catalysis

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Resultssupporting

confidence: 82%

Iron(III) Complexes with Cross‐Bridged Cyclams: Synthesis and Use in Alcohol and Water Oxidation Catalysis

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…For instance, ion pairs in nonpolar solvents likely form 3D spheroidal aggregates rather than 2D linear systems; the spherical approximation might still hold in this case. As a matter of fact, methods based on Equation (1) for the study of ion‐pair aggregation are well established . Likewise, other common applications concern the study of, for example, dendrimers and self‐assembled supramolecular systems…”

Section: Resultsmentioning

confidence: 99%

Extraction of Reliable Molecular Information from Diffusion NMR Spectroscopy: Hydrodynamic Volume or Molecular Mass?

Zaccaria

Zuccaccia

Cipullo

et al. 2019

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

Measuringa ccurate translational self-diffusion coefficients (D t )b yN MR techniques with modern spectrometers has becomer ather routine. In contrast, the derivation of reliablem oleculari nformation therefrom still remains an ontrivial task. In this paper,t wo established approaches to estimating molecular size in termso fh ydrodynamicv olume( V H ) or molecular weight (M) are compared. Ad hoc designede xperiments allowed the criticala spects of their application to be explored by translatingr elativelyc omplex theoretical principles into practical take-homem essages. For instance, comparing the D t values of three isosteric Cp 2 MCl 2 complexes (Cp = cyclopentadienyl,M = Ti,Z r, Hf), having significantly differentm olecularm ass, provided an empiricald em-onstration that V H is the criticalm olecular property affecting D t .T his central concept served to clarify the assumptions behindt he derivation of D t = f(M) power laws from the Stokes-Einstein equation. Somep itfalls in establishing log (D t )v ersus log (M) linear correlations for as et of species have been highlighted by further investigations of selected examples. The effectiveness of the Stokes-Einstein equation itself in describing the aggregation or polymerization of differently shaped speciesh as been explored by comparing, for example, ab all-shaped silsesquioxane cage with its cigarlike dimeric form, or styrenew ith polystyrene macromolecules.[a] Dr.Supporting Information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

show abstract

“…This leads us to suspect that, again, this difference in behavior with the complex was a manifestation of its ionic character. The two likely possibilities for the higher than expected molecular weight in CD 3 CN are (1) aggregation of several ions , and (2) solvent molecules pairing to and moving with the cation in solution slowing diffusion. Both processes are equilibria involving relatively weak, dynamic interactions between the cation and other species in solution.…”

Section: Results and Discussionmentioning

confidence: 99%

Weakly Coordinating yet Ion Paired: Anion Effects on an Internal Rearrangement

et al. 2017

View full text Add to dashboard Cite

“Weakly coordinating anions” such as tetraarylborates are ubiquitous in applications of inorganic and organometallic chemistry, with great industrial importance. In this work, we probe the ion-pairing ability of these weakly coordinating anions using the highly sensitive chromium(VI) nitrido bis(diisopropylamido) system NCr(N-i-Pr2)2X, with one variable coordination site (X). This system is being used in the quantification of ligand donor ability to high-valent metal centers and has simply been called the ligand donor parameter (LDP). The donor ability of the variable ligand can be measured by solution-state rotational barrier studies via NMR spectroscopy. If the variable ligand is neutral, the chromium complex is cationic, {NCr(N-i-Pr2)2L}+, with its pendant anion. Despite the weakly coordinating nature of the counteranions employed, a significant amount of ion pairing has been noted in solution, the result of which is substantial enough to perturb the sensitive LDP measurement. These effects have been noted for many commonly used counteranions, including hexafluoroantimonate(V), hexafluorophosphate(V), tetraphenylborate, and tetrakis(bis(3,5-trifluoromethyl)phenyl)borate (BArF24). Using diffusion ordered (DOSY) and rotating-frame Overhauser effect (ROESY) NMR spectroscopy and LDP values, we have shown, predictably, that the extent of ion pairing is solvent dependent and appears to be minimized by increasing the dielectric constant of the NMR solvent utilized. Additionally, we have gained insight into differences in the nature of ion pairing dependent upon the identity of the weakly coordinating anion employed. It was found that the tetraarylborate anions appear to be fully ion paired in CDCl3 but affect amido rotation less in comparison to other anions. We postulate that the smaller effect on the internal rearrangement by these fluorinated tetraarylborate anions is due to a lack of specificity in the interaction with the cation rather than a lack of ion pairing, which may be a general feature of these anions.

show abstract

Disclosing the multi-faceted world of weakly interacting inorganic systems by means of NMR spectroscopy

Cited by 21 publications

References 42 publications

Iron(III) Complexes with Cross‐Bridged Cyclams: Synthesis and Use in Alcohol and Water Oxidation Catalysis

Iron(III) Complexes with Cross‐Bridged Cyclams: Synthesis and Use in Alcohol and Water Oxidation Catalysis

Extraction of Reliable Molecular Information from Diffusion NMR Spectroscopy: Hydrodynamic Volume or Molecular Mass?

Weakly Coordinating yet Ion Paired: Anion Effects on an Internal Rearrangement

Contact Info

Product

Resources

About