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solid-state NMR and density functional theory studies of vanadium environments in dipicolinic acid complexes
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10.1063/1.2830239
/content/aip/journal/jcp/128/5/10.1063/1.2830239
http://aip.metastore.ingenta.com/content/aip/journal/jcp/128/5/10.1063/1.2830239

Figures

Image of FIG. 1.
FIG. 1.

Molecular structures of the V(V)-dipicolinate derivatives under investigation: [(a)–(e)] derivatives and [(f)–(h)] V(V)O derivatives.

Image of FIG. 2.
FIG. 2.

MAS NMR spectra of (compound e) acquired at different MAS frequencies: (a) , (b) , (c) , and (d) .

Image of FIG. 3.
FIG. 3.

MAS NMR spectra of the five-coordinate -dipicolinate derivatives shown in Fig. 1(a)–1(e): (a) ; (b) ; (c) ; (d) ; and (e) . The spectra were acquired at a spinning frequency of .

Image of FIG. 4.
FIG. 4.

Experimental spectrum (a) compared to the spectrum simulated in SIMPSON (b) for [compound a, Fig. 1(a)] at .

Image of FIG. 5.
FIG. 5.

Comparison of experimental and calculated quadrupolar coupling constant for the five- and seven-coordinate vanadium(V)-dipicolinate derivatives under investigation computed using different geometries: (a) x-ray geometry with counterions and hydration water molecules included; (b) x-ray geometry without counterions and hydration water molecules; and (c) optimized geometries with no counterions or hydration water molecules. Dotted line is best fit, and solid line represents an ideal agreement between calculated and experimental . Different symbols represent different DFT methods used: open circle, PBE1PBE exchange-correlation functional and basis set; open square, B3LYP exchange-correlation functional and basis set; closed circle, PBE1PBE exchange-correlation functional and TZVP basis set; and closed square: B3LYP exchange-correlation functional and TZVP basis set. The fit parameters are entered in Table II.

Image of FIG. 6.
FIG. 6.

Quadrupolar coupling constants calculated using different basis sets for (a) , (b) , (c) , (d) , (e) , (f) , and (g) . The solid line represents the experimentally determined , and the shaded area represents the experimental error.

Image of FIG. 7.
FIG. 7.

Comparison of experimental and calculated principal components of the chemical shift anisotropy tensor for different groups of compounds: (a) full set, (b) , and (c) V(V)O. Dotted line is best fit, and solid line represents an ideal agreement between calculated and experimental . Different symbols represent different DFT methods used: open circle, PBE1PBE exchange-correlation functional and basis set; open square, B3LYP exchange-correlation functional and basis set; closed circle, PBE1PBE exchange-correlation functional and TZVP basis set; and closed square: B3LYP exchange-correlation functional and TZVP basis set. The fit parameters are entered in Table III.

Image of FIG. 8.
FIG. 8.

(a) The molecular structure of (compound e) with the unique components of the shielding ( in yellow) and the EFG tensor ( in orange). is perpendicular to the dipicolinate plane, while is perpendicular to the plane. (b) Image of the electrostatic potential surface of compound e created from the total self-consistent field density calculated in GAUSSIAN. The blue indicates regions of negative charge (attracts a positive test charge), while the red represents regions of positive charge (repels a positive test charge). Note the difference in magnitude at the extremes of the scale.

Image of FIG. 9.
FIG. 9.

The four molecular orbitals with the greatest vanadium -character and which contribute the most to the vanadium isotropic paramagnetic shielding with the percent contribution, energy level, and the vanadium -orbital contributions are indicated below the image.

Tables

Generic image for table
Table I.

Experimental solid-state NMR parameters for five- and seven-coordinate vanadium(V)-dipicolinate derivatives. (i) The chemical shift parameters are defined such that and (Ref. 64). The components of the chemical shift tensor are , , and . Note that, according to Haeberlen-Mehring-Spiess, the anisotropy of the CSA tensor is defined as . (ii) The EFG parameters are and , where , is the electron charge, is Planck’s constant, and is the nuclear quadrupolar moment of , (Ref. 65).

Generic image for table
Table II.

Summary of the DFT calculations of the quadrupolar coupling constant : Correlations between calculated and experimental for different starting geometries.

Generic image for table
Table III.

Summary of the DFT calculations of the principal components of the CSA tensor: Correlations between calculated and experimental for different starting geometries.

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/content/aip/journal/jcp/128/5/10.1063/1.2830239
2008-02-04
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: V51 solid-state NMR and density functional theory studies of vanadium environments in V(V)O2 dipicolinic acid complexes
http://aip.metastore.ingenta.com/content/aip/journal/jcp/128/5/10.1063/1.2830239
10.1063/1.2830239
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