NMR spectroscopy of the solid-state isomerization of nitrito- and nitro-pentamminecobalt(III) chloride

2006 ◽  
Vol 84 (2) ◽  
pp. 300-308 ◽  
Author(s):  
Kristopher J Ooms ◽  
Roderick E Wasylishen
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Spin Coupling ◽  
Chemical Shift Tensor ◽  
Coupling Constant ◽  
Line Shapes ◽  
Quadrupolar Coupling ◽  
Shielding Tensor ◽  
Spin Spin Coupling

Cobalt-59 and nitrogen-15 NMR spectra of the nitritopentamminecobalt(III) chloride, [(NH3)5Co-ONO]Cl2, and nitropentamminecobalt(III) chloride, [(NH3)5Co-NO2]Cl2, isomers in the solid state have been obtained at several applied magnetic field strengths. The 59Co NMR line shapes indicate that both the cobalt nuclear quadrupolar coupling constant (CQ) and the span of the chemical shift tensor (Ω) decrease when the complex isomerizes from [(NH3)5Co-ONO]2+ to [(NH3)5Co-NO2]2+; CQ decreases from 23 to 10.3 MHz and Ω changes from 1650 to 260 ppm. The 15N NMR line shapes also show a significant change in the nitrogen magnetic shielding tensor upon isomerization, with Ω decreasing from 710 to 547 ppm; also, an indirect spin-spin coupling, 1J(59Co,15N) = 63 Hz, is observed in the 15N NMR spectra of the nitro isomer. The NMR parameters are rationalized based on differences in the molecular structure of the two isomers. NMR spectra have also been recorded as the isomerization progresses with time and demonstrate the practicality of the technique for the study of solid-state isomerizations.Key words: 15N, 59Co, solid-state NMR, linkage isomerization, chemical shift tensor, electric field gradient tensor.

Cobalt-59 chemical shift and quadrupolar tensors of simple octahedral cobalt(III) complexes

2001 ◽  
Vol 79 (3) ◽  
pp. 296-303
Author(s):  
Christopher W Kirby ◽  
William P Power
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Principal Components ◽  
Solid State Nmr ◽  
Nmr Spectra ◽  
Line Shapes ◽  
Quadrupolar Coupling ◽  
Molecular Frame ◽  
Specific Ligand

Analysis of the solid-state powder 59Co NMR spectra of ten simple inorganic cobalt(III) complexes at 11.75, and in most cases, 4.7 T have permitted the assignment of specific ligand planes to ranges of values of the observed chemical shift principal components. The relevant chemical shift components were determined from the simulations of the powder line shapes. These simulations also provided the relative orientations of the chemical shift (CS) and electric field gradient (efg) tensors, as well as magnitude and asymmetry of the 59Co quadrupolar coupling. Using symmetry arguments and ab initio calculations, as appropriate or necessary, the orientations of the efg tensors in the molecular frame were deduced. This allowed the determination of the CS tensors in the molecular frame and thus assignment of the ligand planes responsible for the observed values of chemical shifts.Key words: cobalt, chemical shift, quadrupolar coupling, solid state NMR.

X-ray diffraction, Raman spectroscopic, and solid-state NMR studies of the group 14 metal-(tetracarbonyl)cobalt complexes Ph3MCo(CO)4 (M = Si, Sn, Pb)

2002 ◽  
Vol 80 (7) ◽  
pp. 813-820 ◽  
Author(s):  
J M Geller ◽  
J H Wosnick ◽  
I S Butler ◽  
D FR Gilson ◽  
F G Morin ◽  
...  
Keyword(s):  
Solid State ◽  
Spin Coupling ◽  
Chemical Shift Tensor ◽  
Coupling Constant ◽  
X Ray Diffraction ◽  
Group 14 ◽  
X Ray ◽  
Fermi Contact ◽  
Spin Spin Coupling ◽  
Cp Mas Nmr

Single-crystal X-ray diffraction studies illustrate that the three title compounds are isomorphous, belonging to the triclinic space group P[Formula: see text], with slightly distorted trigonal bipyramidal geometry about cobalt. The solid-state 29Si, 119Sn, and 207Pb cross-polarization magic angle spinning (CP MAS) NMR spectra are presented. The indirect spin–spin coupling constant (J), quadrupolar–dipolar shift (d), direct dipolar coupling constant (D' ), anisotropy in spin–spin coupling (ΔJ), and the chemical shift tensor were extracted. A plot of the reduced coupling constant vs. s-electron densities at the nucleus indicates that the Fermi contact term may be dominant for the tin and lead complexes; however, the large ΔJ for all complexes indicate that there are also significant anisotropic terms. Trends in the Raman scattering spectra are also discussed.Key words: 29Si, 119Sn, and 207Pb CP MAS NMR, tetracarbonyl cobalt, spin–spin coupling, chemical shift tensor, quadrupole coupling, Fermi contact, cobalt–group 14.

Article

1999 ◽  
Vol 77 (11) ◽  
pp. 1962-1972
Author(s):  
Scott Kroeker ◽  
Roderick E Wasylishen
Keyword(s):  
Nmr Spectra ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Spin Coupling ◽  
Group Symmetry ◽  
Magic Angle ◽  
Chemical Shielding ◽  
Shielding Tensor ◽  
Angle Spinning ◽  
Spin Spin Coupling

Direct NMR observation of copper-63/65 nuclei in solid K3Cu(CN)4 provides the first experimental example of anisotropic copper chemical shielding. Axially symmetric by virtue of the space group symmetry, the shielding tensor spans 42 ppm, with the greatest shielding when the unique axis is perpendicular to the applied magnetic field. The nuclear quadrupole coupling constant is also appreciable, CQ(63Cu) = -1.125 MHz, reflecting a deviation of the Cu(CN)43- anion from pure tetrahedral symmetry. Spin-spin coupling to 13C nuclei in an isotopically enriched sample is quantified by line-shape simulations of both 13C and 63/65Cu magic-angle spinning (MAS) NMR spectra to be 300 Hz. It is shown that this information is also directly available by 63/65Cu triple-quantum (3Q) MAS NMR. The relative merits of these three approaches to characterizing spin-spin couplings involving half-integer quadrupolar nuclei are discussed. Chemical shielding tensors for nitrogen-15 and carbon-13 are obtained from NMR spectra of non-spinning samples, and are compared to those of tetrahedral group 12 tetracyanometallates. Finally, 2J(63/65Cu,15N) detected in 15N MAS experiments are found to be 19 and 20 Hz for the two crystallographically distinct cyanide ligands.Key words: NMR, quadrupolar nucleus, chemical shielding tensor, multiple-quantum magic-angle spinning, metal cyanide, spin-spin coupling.

X-ray diffraction and solid-state 119Sn CP-MAS NMR studies of some triaryltin(IV) chlorides

2003 ◽  
Vol 81 (11) ◽  
pp. 1187-1195 ◽  
Author(s):  
Jordan M Geller ◽  
Ian S Butler ◽  
Denis FR Gilson ◽  
Frederick G Morin ◽  
Ivor Wharf ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Spin Coupling ◽  
Magic Angle ◽  
X Ray ◽  
Tin Chloride ◽  
Angle Spinning ◽  
Spin Spin Coupling

The solid-state 119Sn cross-polarization (CP) magic angle spinning (MAS) NMR spectra of a series of triaryltin chlorides of the form Ar3SnCl have been acquired. The indirect spin-spin coupling constants (J(119Sn-35Cl)), quadrupolar-dipolar shifts (d(119Sn-35Cl)), and the 119Sn chemical shift tensors were extracted. For the spectrum of triphenyltin chloride (I) the validity of the first-order perturbation approximation was tested by comparing results of both the perturbation and cubic-equation approaches and a variable-temperature NMR study undertaken to investigate the influence of the previously reported molecular motion in the solid. The X-ray crystal structures of the tris(o-tolyl)tin chloride (II) and tris(p-tolyl)tin chloride (IV) complexes have been examined. They belong to the monoclinic and triclinic space groups P21/n and P[Formula: see text], respectively, which are different from the previously reported tris(m-tolyl)tin chloride (III) complex, which crystallizes in the space group R3 and has threefold molecular symmetry. The structures and NMR properties of the complexes with meta-substituents are quite different from those with ortho- or para-substituents having axially symmetric shift tensors with small spans and larger J values.Key words: aryltin chlorides, magic angle spinning NMR, tin-chlorine spin-spin coupling, 119Sn chemical shift tensor, crystal structure.

scholarly journals High Resolution and Solid State NMR Investigations of Subvalent Gallium Compounds

1986 ◽  
Vol 41 (1-2) ◽  
pp. 315-318 ◽  
Author(s):  
Hubert Schmidbaur ◽  
Theodore Zafiropoulos ◽  
Wolfgang Bublak ◽  
Paul Burkert ◽  
Frank H. Köhler
Keyword(s):  
Solid State ◽  
Nmr Spectra ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Gallium Atom ◽  
Line Shapes ◽  
Quadrupole Coupling ◽  
Structure Determinations ◽  
Constant E ◽  
Gallium Compounds

The 71Ga NMR spectra of Ga[GaX4] melts and of solutions in benzene and other hydrocarbons show discrete sharp GaI and broad GaIII resonances. In the light of recent structure determinations, the solution GaI signals must be attributed to bis(arene)Ga+ complexes in which the gallium atom is η6-bonded to the hydrocarbons. The low line widths and strong high field shifts are attributed to an almost spherical shielding of the metal nucleus by the 4 s2 electrons. Solid state 69Ga and 71Ga NMR spectra of Ga[GaCl4] crystalline powder show only Ga1 resonances. While the 71GaI line is rather narrow, the 69GaI line has a complex fine structure. Consistent with the crystal structure of Ga[GaCl4], the Ga1 ion is calculated to have a very low quadrupole coupling constant e2q Q/h = 1.7 ± 0.1 MHz and an asymmetry parameter η = 0.44. Experimental and simulated line shapes (using literature models) are in satisfactory agreement, implying that the 69Ga signal splitting is due to second order quadrupolar effects for the central m = + 1/2 ⇋ - 1/2 transition. The analogous splitting of the 71Ga NMR line is too small to be detected.

scholarly journals Linear dicoordinate beryllium: a 9Be solid-state NMR study of a discrete zero-valent s-block beryllium complex

2018 ◽  
Vol 96 (7) ◽  
pp. 646-652 ◽  
Author(s):  
C. Leroy ◽  
J.K. Schuster ◽  
T. Schaefer ◽  
K. Müller-Buschbaum ◽  
H. Braunschweig ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Chemical Shift Tensor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Quadrupolar Coupling ◽  
Nmr Study ◽  
Tensor Data

Beryllium-9 (9Be) quadrupolar coupling and chemical shift tensor data are reported for bis(1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidine-2-ylidene)beryllium (Be(CAAC)2). These are the first such data for beryllium in a linear dicoordinate environment. The 9Be quadrupolar coupling constant, 2.36(0.02) MHz, is the largest recorded in the solid state to date for this isotope. The span of the beryllium chemical shift tensor, 22(2) ppm, covers about half of the known 9Be chemical shift range, and the isotropic 9Be chemical shift, 32.0(0.3) ppm, is the largest reported in the solid state to our knowledge. DFT calculations reproduce the experimental data well. A natural localized molecular orbital approach has been used to explain the origins and orientation of the beryllium electric field gradient tensor. The single-crystal X-ray structure of a second polymorph of Be(CAAC)2 is also reported. Inspection of the powder X-ray diffraction data shows that the new crystal structure is part of the bulk product next to another crystalline phase. Therefore, experimental X-ray powder data for the microcrystalline powder sample and the SSNMR data do not fully match either the originally reported crystal structure (Arrowsmith et al. Nat. Chem. 2016, 8, 890–894) or the new polymorph. The ability of solid-state NMR and powder X-ray diffraction to characterize powdered samples was thus particularly useful in this work.

Solid-state nuclear magnetic resonance studies of triphenylsilyl-, triphenyltin-, and triphenyllead(pentacarbonyl)manganese(I) complexes

1999 ◽  
Vol 77 (11) ◽  
pp. 1892-1898 ◽  
Author(s):  
Dharamdat Christendat ◽  
Ian S Butler ◽  
Denis FR Gilson ◽  
Frederick G Morin
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Dipolar Coupling ◽  
Chemical Shifts ◽  
Chemical Shift Anisotropy ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Chemical Shift Tensors ◽  
Lead Compounds ◽  
Spin Spin Coupling

The solid-state CP MAS (29Si, 119Sn, and 207Pb) NMR spectra of the triphenylsilyl-, triphenyltin-, and triphenyllead(pentacarbonyl)manganese(I) complexes, (Ph3E)Mn(CO)5 (E = Si, Sn, Pb), have been analyzed to give the chemical shifts, one-bond spin-spin coupling constants, 1JE-Mn, the "effective-dipolar" coupling constants (D - ΔJ/3), the chemical shift tensors, and the spin-spin anisotropy (ΔJ), where the analysis permits. For the tin and lead compounds, three and four sets of chemical shifts, respectively, were observed, and two different polymorphs occur for the lead complex, depending on the solvent used for recrystallization. The average values of the reduced coupling constants, 1KMn-Si (2.64 × 1020 T2 J-1), 1KSn-Mn (1.25 × 1020 T2 J-1), and 1KPb-Mn (4.18 × 1020 T2 J-1) showed a linear correlation with the s-electron densities at the respective metal nuclei. The principal components of the chemical shift tensors have been determined for the tin and lead compounds.Key words: manganese-group-14 compounds, solid-state 29Si, 119Sn, and 207Pb CP MAS NMR, spin-spin coupling, chemical shift anisotropy, quadrupole coupling.

Characterization of indirect 31P-31P spin-spin coupling and phosphorus chemical shift tensors in pentaphenylphosphinophosphonium tetrachlorogallate, [Ph3P-PPh2][GaCl4]

2002 ◽  
Vol 80 (11) ◽  
pp. 1488-1500 ◽  
Author(s):  
Myrlene Gee ◽  
Roderick E Wasylishen ◽  
Paul J Ragogna ◽  
Neil Burford ◽  
Robert McDonald
Keyword(s):  
Chemical Shift ◽  
Density Functional ◽  
Dipolar Coupling ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Chemical Shift Tensors ◽  
Self Consistent Field ◽  
Self Consistent Field Theory ◽  
Spin Spin Coupling ◽  
Phosphorus Nucleus

Phosphorus chemical shift and 31P,31P spin-spin coupling tensors have been characterized for pentaphenylphosphinophosphonium tetrachlorogallate, [Ph3P-PPh2][GaCl4], using solid-state 31P NMR spectroscopy. Spectra obtained with magic-angle spinning yield the isotropic value of the indirect spin-spin coupling, |1J(31P,31P)iso|, 323 ± 2 Hz, while 2D spin-echo and rotational resonance experiments provide the effective dipolar coupling constant, Reff, 1.70 ± 0.02 kHz, and demonstrate that Jiso is negative. Within experimental error, the effective dipolar coupling constant and Jiso are unchanged at –120°C. The anisotropy in 1J(31P,31P), ΔJ, has been estimated by comparison of Reff and the value of the dipolar coupling constant, RDD, calculated from the P—P bond length as determined by X-ray diffraction. It is concluded that |ΔJ| is small, with an upper limit of 300 Hz. Calculations of 1J(31P,31P) for model systems H3P-PH+2 and (CH3)3P-P(CH3)+2 using density functional theory as well as multiconfigurational self-consistent field theory (H3P-PH+2) support this conclusion. The experimental spin-spin coupling parameters were used to analyze the 31P NMR spectrum of a stationary powder sample and provide information about the phosphorus chemical shift tensors. The principal components of the phosphorus chemical shift tensor for the phosphorus nucleus bonded to three phenyl groups are δ11 = 36 ppm, δ22 = 23 ppm, and δ33 = –14 ppm with an experimental error of ±2 ppm for each component. The components are oriented such that δ33 is approximately perpendicular to the P—P bond while δ11 forms an angle of 31° with the P—P bond. For the phosphorus nucleus bonded to two phenyl groups, the principal components of the phosphorus chemical shift tensor are δ11 = 23 ppm, δ22 = –8 ppm, and δ33 = –68 ppm with experimental errors of ±2 ppm. In this case, δ33 is also approximately perpendicular to the P—P bond; however, δ22 is close to the P—P bond for this phosphorus nucleus, forming an angle of 13°. The dihedral angle between the δ33 components of the two phosphorus chemical shift tensors is 25°. Results from ab initio calculations are in good agreement with experiment and suggest orientations of the phosphorus chemical shift tensors in the molecular frame of reference.Key words: Nuclear magnetic resonance spectroscopy, phosphorus chemical shift tensors, 31P-31P J-coupling tensors, density functional theory, multiconfigurational self-consistent field theory, phosphinophosphonium salts.

Reconnaissance of diverse structural and electronic environments in germanium halides by solid-state 73Ge NMR and quantum chemical calculations

2011 ◽  
Vol 89 (9) ◽  
pp. 1118-1129 ◽  
Author(s):  
Brandon J. Greer ◽  
Vladimir K. Michaelis ◽  
Victor V. Terskikh ◽  
Scott Kroeker
Keyword(s):  
Solid State ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Coupling Constant ◽  
Electronic Environments ◽  
Isotropic Chemical Shifts ◽  
Spin Spin Coupling

Solid-state 73Ge nuclear magnetic resonance (NMR) is an attractive technique for the characterization of solid germanium-containing materials, but experiments can be exceedingly difficult in practice due to the unfavourable NMR properties of the 73Ge nucleus. Presented herein is a series of solid-state 73Ge NMR experiments on germanium halides (GeX4 and GeX2, where X = I, Br, and Cl) conducted at moderate (9.4 and 11.7 T) and ultrahigh (21.1 T) magnetic fields, intended to characterize the 73Ge NMR response in highly symmetric and asymmetric coordination environments. Quadrupole coupling constants range from 0.16 to 35 MHz. Isotropic chemical shifts for the GeX4 series trend with halide electronegativity, as found for the analogous silicon and tin halides. The indirect spin-spin coupling constant 1J(73Ge, 127I) is estimated from 73Ge MAS NMR to be 35 ± 10 Hz in GeI2, with the reduced coupling constant agreeing with those of other group 14 halides. Quantum chemical calculations using GIPAW DFT are in reasonable accord with experimental quadrupole couplings, but fail for chemical shielding. A preliminary NMR crystallographic study of GeI2 and GeCl2 incorporating 127I and 35Cl NMR spectra has led to plausible conclusions reflecting the structural homology of these compounds, although definitive characterization remains elusive.

A solid state NMR and molecular orbital study of hydroxylammonium chloride

1999 ◽  
Vol 77 (11) ◽  
pp. 1813-1820 ◽  
Author(s):  
Glenn H Penner ◽  
YC Phillis Chang ◽  
H Michelle Grandin
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Chemical Shift ◽  
Molecular Orbital ◽  
Solid State Nmr ◽  
Coupling Constants ◽  
Basis Sets ◽  
Exponential Factor ◽  
Line Shapes ◽  
Quadrupolar Coupling

Deuterium and nitrogen-15 NMR spectroscopy has been used to measure the 2H quadrupolar coupling and 15N chemical shift tensors in solid hydroxylammonium chloride, NH3OH+Cl-, (HAC). In addition, the NH3 and OH dynamics have been investigated by variable temperature 2H line shapes and T1 measurements. The Arrhenius activation energy for NH3 rotation is 22.5 ± 1.8 kJ/mol with a pre-exponential factor of 8 ± 3 × 1012 s-1 from line shapes and 21.3 ± 2 kJ/mol with an infinite temperature correlation time, τinf,, of 5.0 ± 0.4 × 10-14 s from the T1 analysis. The latter value corresponds to a pre-exponential factor of 6.7 ± 0.5 × 1012 s-1, if a three-site exchange is assumed. There was no evidence for OH reorientation up to 405 K, indicating a rather strong OH···Cl hydrogen bond. Previously reported inconsistencies between crystal structure and molecular orbital derived N-O bond lengths are cleared up by performing geometry optimizations with large basis sets and taking electron correlation into account. The internal rotational potential for the isolated HA cation is calculated to be 5.8 kJ/mol at the MP2/6-31G** level, with the trans geometry preferred. Calculations that employ the neutron diffraction geometry and include the Cl- anions that surround the HA+ cation yield an upper limit for the activation energy for NH3 group rotation of 62 kJ/mol. Analysis of the deuterium spectrum and T1 data yield nuclear quadrupolar coupling constants of 160 ± 5 kHz and 194 ± 5 kHz (η = 0.50 ± 0.05) for the ND3 and OD deuterons, respectively. Density functional calculations of the deuterium and nitrogen-14 nuclear quadrupolar coupling constants at the B3LYP level show that it is necessary to include the influence of the surrounding chloride anions. We have also shown that it is possible to obtain accurate proton chemical shifts from the deuterium MAS spectrum of solid HAC-d4.Key words: solid state NMR, molecular dynamics, nitrogen 15 chemical shift anisotropy.

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