Solid-state 25Mg NMR, X-ray crystallographic, and quantum mechanical study of bis(pyridine)-(5,10,15,20-tetraphenyl porphyrinato)magnesium(II)

2003 ◽  
Vol 81 (4) ◽  
pp. 275-283 ◽  
Author(s):  
Gang Wu ◽  
Alan Wong ◽  
Suning Wang
Keyword(s):  
Solid State ◽  
Bond Distance ◽  
Quadrupole Coupling Constant ◽  
Basis Set ◽  
Quantum Mechanical ◽  
Chemical Calculation ◽  
Porphyrin Ring ◽  
Coupling Constant ◽  
X Ray ◽  
Quadrupole Coupling

We report solid-state 25Mg NMR, X-ray crystallographic, and quantum-mechanical calculation results for bis(pyridine)(5,10,15,20-tetraphenylporphyrinato)magnesium(II), Mg(TPP)·Py2. Mg(TPP)·Py2 crystallizes in the triclinic form, in the space group P[Formula: see text]. The unit cell parameters are: a = 9.6139(13) Å, b = 11.0096(16) Å, c = 11.8656(15) Å; α = 102.063(3)°, β = 103.785(3)°, γ = 114.043(2)°; Z = 1. The Mg(II) ion is coordinated to four nitrogen atoms from the porphyrin ring and two nitrogen atoms from the axial pyridine ligands, forming a regular octahedron. The 25Mg quadrupole coupling constant (CQ) is 15.32 ± 0.02 MHz, which represents the largest value so far observed for 25Mg nuclei. The electric field gradient tensor at the Mg site is axially symmetric, ηQ = 0.00 ± 0.05. The 25Mg chemical shielding anisotropy is too small to be accurately determined. Quantum-mechanical calculations using a 6–31G(d) basis set reproduce reasonably well the observed 25Mg NMR data for Mg(TPP)·Py2. The calculations also suggest that the span of the 25Mg chemical shift tensor is less than 50 ppm. Using a theoretical approach, we also investigate the dependence of the 25Mg quadrupole coupling constant on the Mg—Nax bond distance. The calculation suggests that the 25Mg quadrupole coupling constant for an Mg(II) ion at the center of a porphyrin ring without axial ligands is approximately 22 MHz, which may be treated as an upper limit of the 25Mg quadrupole coupling constant for all Mg–porphyrin complexes.Key words: 25Mg NMR, crystal structure, quantum chemical calculation, quadrupole parameter, tetraphenylporphyrin.

scholarly journals 7Li Solid State NMR Study of a TMEDA Complex of Trimethylsilylcyclopentadienyllithium

1993 ◽  
Vol 48 (11) ◽  
pp. 1555-1557 ◽  
Author(s):  
Tanja Pietraß ◽  
Paul K. Burkert
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Quadrupole Coupling Constant ◽  
Structural Features ◽  
Coupling Constant ◽  
X Ray ◽  
Nmr Study ◽  
Quadrupole Coupling ◽  
Increasing Temperature

7Li solid state NMR spectroscopy of Ν,Ν,N′,N′-tetramethylethylenediamine-trimethylsilylcyclopentadienyllithium yielded an unusually large quadrupole coupling constant, that decreases with increasing temperature (188-165 kHz in the temperature range 210-335 K). Structural features, known from the X-ray analysis, are compared with the NMR results.

Electric Quadrupole Moment of the 14N Nucleus Determined by ab initio Cl Calculation on NH3

1986 ◽  
Vol 41 (1-2) ◽  
pp. 163-165 ◽  
Author(s):  
Tae-Kyu Ha
Keyword(s):  
Electric Field Gradient ◽  
Ab Initio ◽  
Electric Quadrupole ◽  
Quadrupole Coupling Constant ◽  
Basis Set ◽  
Electric Quadrupole Moment ◽  
Coupling Constant ◽  
Hartree Fock ◽  
Quadrupole Coupling ◽  
Constant E

Based on the calculated electric field gradient (q) from ab initio Cl wavefunctions with largebasis set (including ƒ functions on N and d functions on H) and the experimental nuclearquadrupole coupling constant (e Q q) for nitrogen in NH3, an improved value o f the quadrupole moment of 14N is proposed as Q (14N ) = 2.08 x 10-26cm2. The value calculated using a wavefunctionnear the Hartree-Fock limit enlarged ≈ 10% by the Cl treatment.

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.

The 59Co nuclear magnetic resonance spectra of polycrystalline complexes

1987 ◽  
Vol 65 (6) ◽  
pp. 1332-1335 ◽  
Author(s):  
Donald R. Eaton ◽  
Richard J. Buist ◽  
Brian G. Sayer
Keyword(s):  
Chemical Shift ◽  
Chemical Shift Anisotropy ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
X Ray ◽  
Low Field ◽  
Nmr Data ◽  
Nuclear Magnetic Resonance Spectra ◽  
Quadrupole Coupling ◽  
Low Field Nmr

The solid state 59Co nmr spectra of a number of octahedral complexes are reported. In the case of sodium hexanitrocobaltate(III) the spectra have been obtained at several different field strengths and the results are analysed to give a quadrupole coupling constant of 9.4 MHz, an asymmetry parameter of zero and an axial chemical shift tensor with an anisotropy of 180 ppm. Several other complexes have been examined at high field (11.8 T) to minimize the effects of quadrupole coupling and maximize the influence of chemical shift anisotropy. The results are, where possible, compared with single crystal X-ray and low field nmr data. It is concluded that high fields are necessary to obtain reliable chemical shift anisotropy values. The conditions necessary for obtaining reasonable quality spectra from polycrystalline samples containing quadrupolar nuclei are discussed.

7Li-Solid-State-NMR of [Li(N,N,N',N'-Tetramethylethylenediamine)] CLO4 and [Li (N,N,N', N'-Tetramethylethylenediamine)2] Al(CH3)4

1992 ◽  
Vol 47 (1-2) ◽  
pp. 117-119 ◽  
Author(s):  
Tanja Pietraß ◽  
Paul K. Burkert ◽  
Hans H. Karsch
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Quadrupole Coupling Constant ◽  
Positive Temperature ◽  
Coupling Constant ◽  
Axially Symmetric ◽  
Temperature Range ◽  
Central Transition ◽  
Quadrupole Coupling ◽  
Motional Narrowing

Abstract The temperature dependent 7Li-solid-state-NMR spectra of the two compounds [Li(N,N,N',N'- tetramethylethylenediamine)]ClO4 and [Li(N,N,N\N tetramethylethylenediamine)2]Al(CH3)4 are presented. Both compounds were investigated in the temperature range 160 K ≦ T ≦ 360 K. Above room temperature, the spectra for the tetramethylaluminate show the typical line shape for a first-order quadrupolar-disturbed central transition with an axially symmetric asymmetry parameter and a slightly positive temperature dependence of the quadrupole coupling constant. The mean temperature coefficient ά = + 9 • 10-4 K -1 . The quadrupole coupling constant is in the range of 36-39 kHz. In the Temperature range 240 K ≦ T ≦ 275 K the quadrupolar splitting cannot be resolved. Below 240 K the quadrupole coupling constant is about 100 kHz. Contrarily, in the Perchlorate the quadrupole coupling constant is 75 kHz and is temperature independent. With increasing temperature the satellites lower in intensity and the central transition undergoes motional narrowing

A solid-state 35/37Cl NMR study of a chloride ion receptor and a GIPAW-DFT study of chlorine NMR interaction tensors in organic hydrochlorides

2011 ◽  
Vol 89 (7) ◽  
pp. 822-834 ◽  
Author(s):  
Rebecca P. Chapman ◽  
Jennifer R. Hiscock ◽  
Philip A. Gale ◽  
David L. Bryce
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Density Functional ◽  
Chloride Ion ◽  
Quadrupole Coupling Constant ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
High Symmetry ◽  
Coupling Constant ◽  
Quadrupole Coupling

The results of a 35/37Cl solid-state nuclear magnetic resonance (SSNMR) study of the 1-butyl-3-methylimidazolium chloride complex of meso-octamethylcalix[4]pyrrole (1) are reported. Line shapes obtained from magic-angle-spinning and stationary powder samples collected at 9.4 and 21.1 T are analyzed to provide the 35/37Cl quadrupolar tensor and chemical shift (CS) tensor and their relative orientation. The relatively high symmetry of the chloride ion coordination environment is manifested in the small value of the quadrupole coupling constant, CQ(35Cl) = 1.0 MHz. The isotropic chemical shift of 120 ppm (with respect to NaCl(s)) is at the upper edge of the typical range seen for organic hydrochlorides. Consideration of chemical shift anisotropy (span, Ω = 50 ppm) and non-coincidence of the quadrupolar and CS tensors were essential to properly simulate the experimental spectra. The utility of gauge-including projector-augmented wave density functional theory (GIPAW-DFT) calculations of chlorine quadrupolar and CS tensors in organic chlorides was explored by validation against available benchmark experimental data for solid amino acid hydrochlorides. The calculations are shown to systematically overestimate the value of the 35Cl quadrupole coupling constant. Additional calculations on various hydrated and solvated models of 1 are consistent with a structure in which solvent and water of hydration are absent.

A DFT INVESTIGATION ON BASIS SET SIZE AND HYDROGEN-BONDING EFFECTS ON 17O AND 2H NQR PARAMETERS

2013 ◽  
Vol 12 (04) ◽  
pp. 1350022 ◽  
Author(s):  
MEHDI D. ESRAFILI ◽  
NAFISEH MOHAMMADIRAD
Keyword(s):  
Density Functional ◽  
Quadrupole Coupling Constant ◽  
Basis Set ◽  
Basis Sets ◽  
Coupling Constant ◽  
Dft Methods ◽  
Functional Theory ◽  
Set Size ◽  
Quadrupole Coupling ◽  
Consistent Basis

A systematic theoretical study on various maleic acid (MA) clusters has been carried out employing density functional theory (DFT) methods. The performance of two different functionals namely B3LYP and M06 in the prediction of geometries, 17 O and 2 H nuclei quadrupole coupling constant (CQ) values of the MA clusters has been assessed comparing the results to those experimental data. For DFT calculations, several basis sets have been used, including the recently developed Jensen's polarization-consistent basis set families, pcJ-n and pcS-n (n = 0,1,2,3). Calculations at the basis set limit indicate that the value of CQ(2 H ) in monomer MA, changes by 0.01–0.04 kHz for each of the final two basis set increments, and seems reasonable to conclusion that the pcJ-3 result is within a few kHz of the basis set limit. Convergence with respect to basis set size was found to be very good, and the pcJ-1 and pcS-1 basis sets provided a good compromise between the basis set limit and computational expense. In most cases, the differences between B3LYP and M06 results for a given basis set are in a range of 1–2%. On the other hand, no systematic changes in the CQ(17 O ) or CQ(2 H ) were found for basis sets larger than double-ζ. Thus, the usual assumption that double-ζ basis set (pcJ-1 and pcS-1) results in the acceptable CQ values, seems to be valid in the case of 17 O and 2 H nuclei.

Conformational Analysis of Chloromethylenimine and its Hydrogen-Bonded Dimers with Water from the Study of Nuclear Quadrupole Interactions

1996 ◽  
Vol 51 (5-6) ◽  
pp. 534-536 ◽  
Author(s):  
N. Sathyan ◽  
V. Santhanam ◽  
J. Sobhanadri
Keyword(s):  
Proton Affinity ◽  
Quadrupole Coupling Constant ◽  
Basis Set ◽  
Coupling Constant ◽  
Quadrupole Interactions ◽  
Nuclear Quadrupole Interactions ◽  
Nuclear Quadrupole Coupling Constant ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Hydrogen Bonded

Abstract A molecular conformation study on N-Chloromethylenimine and its 1:1 dimeric form with water has been carried out using the ab-initio method at 6-31 G and 6-31 G* basis set. We consider the two most stable conformers of the N-chloromethylenimine -water binary mixture involving double hydrogen bonds. In all cases the proton affinity has been calculated. Each system considered in this work has the nuclear quadrupole interactions of the nitrogen and chlorine resonant nuclei which have been calculated and compared. It is found that the nuclear quadrupole coupling constant for the nitrogen nucleus increases in the hydrogen bonded complexes and decreases for the chlorine nucleus compared to the monomeric values. The influence of proton affinity is reflected in the nuclear quadrupole coupling constant.

Nuclear quadrupole resonance of 14N in ethylenimine

1970 ◽  
Vol 25 (7) ◽  
pp. 1155-1156
Author(s):  
Tae-Kyu Ha ◽  
Chester T. O’Konski
Keyword(s):  
Solid State ◽  
Nuclear Quadrupole Resonance ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Gaseous State ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

The nuclear quadrupole resonance (NQR) spectra of 14N in ethylenimine have been detected at 77 °K. Comparing to the reported microwave experiment on the gaseous state, it is found that the solid state shift in the quadrupole coupling constant is much smaller than that of ammonia

133Cs Nuclear Quadrupole Coupling in CsOH · H20 Through the 232 K Transition

1986 ◽  
Vol 41 (1-2) ◽  
pp. 279-282
Author(s):  
D. T. Amm ◽  
S. L. Segel
Keyword(s):  
Solid State ◽  
Quadrupole Coupling Constant ◽  
Atomic Motion ◽  
Coupling Constant ◽  
Discontinuous Change ◽  
Proton Diffusion ◽  
Α Phase ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Pseudosingle Crystal

The 133Cs NMR has been observed in a pseudosingle crystal of CsOH · H20 in all three solid state phases. The 133Cs quadrupole coupling constant varies almost linearly with temperature throughout the three phases (e2qQ/h = 156 ± 1 kHz at 193 K, 101 ± 1 kHz at 295 K, 36.4 ± 0.5 at 410 K). There is also a discontinuous change of (13 ± 2) kHz in the cesium coupling at the monoclinic to Hex ß transition. In contrast to previous neutron scattering experiments, which indicate significant atomic motion in the Hex α phase, the temperature dependence of the proton NMR indicates that proton diffusion occurs in the Hex ß phase.

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