Phosphorus−Phosphorus Coupling Constants in Mixed-Phosphine Tricarbonyl Iron Complexes, Fe(CO)3LL‘. Crystal Structure oftrans-Fe(CO)3(PEt3)(PPh3)

1997 ◽  
Vol 16 (11) ◽  
pp. 2246-2253 ◽  
Author(s):  
Richard L. Keiter ◽  
John William Benson ◽  
Ellen A. Keiter ◽  
Travis A. Harris ◽  
Matthew W. Hayner ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Iron Complexes ◽  
Coupling Constants

Multinuclear NMR spectra of [Pt(L)Cl3]− (L = pyridine derivatives) complexes and crystal structure of trans-Pt(2,6-di(hydroxymethyl)pyridine)2Cl2•2H2O

1996 ◽  
Vol 74 (11) ◽  
pp. 2121-2130 ◽  
Author(s):  
Fernande D. , ◽  
Corinne Bensimon ◽  
André L. Beauchamp
Keyword(s):  
Crystal Structure ◽  
Pyridine Ring ◽  
Chemical Shifts ◽  
Bond Distance ◽  
Coupling Constants ◽  
Mirror Plane ◽  
Pyridine Derivative ◽  
Pyridine Derivatives ◽  
Pyridine Ligand ◽  
Twofold Axis

Complexes of the type [Pt(L)Cl3]− (L = pyridine derivative) were synthesized and studied by 13C and 195Pt NMR spectroscopies. The 195Pt signals were observed between −1720 and −1897 ppm. No correlation between the δ(Pt) and the pKa of the protonated pyridine derivatives was found. The chemical shifts vary with the substituents on the pyridine ligand. Compounds with substituents in ortho positions were observed at lower fields, except for complexes containing hydroxy or amine groups. The latter compounds were observed at higher fields, close to the signals of the Pt-unsubstituted pyridine compound. These results were explained in terms of the solvent effect. The chemical shifts δ(C) and the coupling constants J(13C–195Pt) were measured and the results interpreted with a view of obtaining information on the nature of the Pt—N bond. The possibility of π-bonding between platinum and the pyridine ligand is examined. The conformation of the pyridine ring in relation to the platinum plane and the energies of the rotation barriers around the Pt—N bond in these types of platinum(II) complexes are briefly discussed. The crystal structure of trans-Pt(2,6-(HOCH2)2py)2Cl2•2H2O was determined by X-ray diffraction. The compound is monoclinic, C2/m, a = 7.022(6), b = 15.646(13), c = 8.344(10) Å, β = 93.35(8)°, Z = 2, R = 0.037. The platinum atom is located at the junction of the twofold axis and the mirror plane, the N atoms and the para-C atom of the pyridine ring are situated on the twofold axis, and the chloride ligands are on the mirror plane. The compound crystallizes with molecules of water, which are H-bonded to the hydroxy groups. The Pt—Cl bond distance is 2.306(2) Å, and that of the Pt—N bond is 2.041 (6) Å. The dihedral angle between the platinum and the pyridine planes is 79.8°. Key words: platinum, pyridine derivatives, NMR, crystal structure.

Nuclear magnetic resonance studies on the anions [M(SnCl3)5Cl]4− (M = Ru, Os) and [Ru(SnCl3)5(MeCN)]3−: the X-ray crystal structure of [N(C2H5)4]4[Ru(SnCl3)5Cl]

1982 ◽  
Vol 60 (11) ◽  
pp. 1304-1316 ◽  
Author(s):  
Louis J. Farrugia ◽  
Brian R. James ◽  
Claude R. Lassigne ◽  
Edward J. Wells
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Octahedral Geometry ◽  
Coupling Constants ◽  
Order Effects ◽  
Magnetic Resonance Studies ◽  
X Ray ◽  
Crystallographic Study

The octahedral anions [M(SnCl3)5Cl]4− (M = Ru, Os) have been fully characterized by 119Sn FT nmr spectroscopy. For M = Ru, 117Sn and 115Sn nmr spectra were also recorded, and an X-ray crystallographic study was carried out on the tetraethylammonium salt, isolated as a disolvate from acetonitrile. The Ru—Sn bond lengths indicate some degree of dπ–dπ interactions. The slight distortions from octahedral geometry are discussed in connection with the packing of the chlorine atoms. The Sn nmr spectra reveal the first observed coupling to a 99Ru nucleus (I = 5/2, 12.7% natural abundance), very large 2J(119Sn—117Sn) coupling constants, and the first observed second-order effects on a heteronuclear system. The octahedral anion [Ru(SnCl3)5(MeCN)]3− was also synthesized as the tetraethylammonium salt and characterized spectroscopically.

scholarly journals Hydrogen Bond Studies. 125. A Deuteron Magnetic Resonance Study of Strontium Formate Dihydrate, Sr(HCOO)2 · 2D2O

1977 ◽  
Vol 32 (9) ◽  
pp. 1025-1029 ◽  
Author(s):  
Bo Berglund ◽  
Jörgen Tegenfeldt
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Magnetic Resonance ◽  
Electric Field Gradient ◽  
Room Temperature ◽  
Coupling Constants ◽  
Water Molecules ◽  
Magnetic Resonance Study ◽  
Quadrupole Coupling ◽  
Asymmetry Parameters

AbstractA room temperature (25 °C) deuteron magnetic resonance (DMR) study of a single crystal of Sr (HCOO)2 · 2 D2O is reported. Signals from all water molecules in the unit cell have been detected, and all four independent electric field gradient (EFG) tensors at the water deuterons have been determined from 409 quadrupole splittings. All spectra were recorded by rotating the crystal about one arbitrarily selected axis. The following quadrupole coupling constants and asymmetry parameters for the deuterons were obtained: 213.5(4), 189.3(4), 195.7(4) and 200.7(5) kHz and 0.117(3), 0.110(4), 0.116(4) and 0.098(3). The directions of the eigenvalues are qualitatively consistent with the crystal structure refined by Galigné 1; the result is in disagreement, however, with the earlier DMR study of Sr (DCOO)2 · 2 D2O (Reference 2).

14N Nuclear Quadrupole Coupling in Glycyl-Glycine and Related Peptides

1984 ◽  
Vol 39 (11) ◽  
pp. 1108-1111 ◽  
Author(s):  
Michael Palmer
Keyword(s):  
Crystal Structure ◽  
Ab Initio ◽  
Ab Initio Calculation ◽  
Coupling Constants ◽  
Double Zeta ◽  
Quadrupole Coupling ◽  
Aromatic Systems ◽  
Nuclear Quadrupole ◽  
Glycyl Glycine

An ab initio calculation of double zeta quality on glycyl-glycine at the crystal structure yielded nuclear quadrupole coupling constants at the peptide centres very close to experiment; Xzz -3.03, Xyy +2.14, Xxx +0.89 MHz. The first two couplings lie in the local π-direction, and along the C-N bond, respectively. At the NH⊕3 centre the values were less satisfactory, but the (low) positive value of Xzz was obtained, and lies relatively close to the N-C bond. The results suggest that similar calculations may be successful for other H-bonded systems, provided that aromatic systems are not involved.

Synthesis and Reactions of (1,1′-Bi-1H-phosphirene)iron Complexes − Crystal Structure of a Bridged (1-Phosphaallyl-1H-phosphirene)diiron(Fe−Fe) Complex

2001 ◽  
Vol 2001 (8) ◽  
pp. 2067-2073 ◽  
Author(s):  
Jürgen Simon ◽  
Guido J. Reiß ◽  
Uwe Bergsträßer ◽  
Heinrich Heydt ◽  
Manfred Regitz
Keyword(s):  
Crystal Structure ◽  
Iron Complexes ◽  
Fe Complex

Crystal structure of E-1-(2,4,6-trimethylphenyl)ethanone oxime. The aryl–oxime rotational barrier problem and 13C—15N nmr coupling constant calculations

1980 ◽  
Vol 58 (2) ◽  
pp. 191-196 ◽  
Author(s):  
Suzanne Fortier ◽  
George I. Birnbaum ◽  
Gerald W. Buchanan ◽  
Brian A. Dawson
Keyword(s):  
Crystal Structure ◽  
Large Angle ◽  
Molecular Geometry ◽  
Coupling Constants ◽  
15N Nmr ◽  
Oxime Group ◽  
Internal Ring ◽  
Coupling Constant ◽  
X Ray ◽  
Barrier Problem

From an X-ray analysis of the title compound it is found that the dihedral angle between the plane of the aromatic ring and the oxime plane is 70.8 °. This large angle precludes a significant π electron overlap between the oxime function and the benzene ring. The distortions of the internal ring angles attributable to the four substituents are examined in detail, and parameters are derived for the oxime group. The aryl–oxime C—C bond length (1.491 Å) is the longest yet reported for an aromatic oxime. Using the X-ray derived geometry as input for the calculation of 13C—15N coupling constants, one obtains markedly better agreement between calculated and observed couplings than was the case when a force-field calculated molecular geometry was employed. The barrier to rotation about the aryl–oxime bond is estimated to be about 5.8 kcal/mol.

Total assignment of the 1H and 13C spectra of mikanokryptin and comparison of its solution and solid state conformations

1985 ◽  
Vol 63 (4) ◽  
pp. 849-853 ◽  
Author(s):  
William F. Reynolds ◽  
Raul G. Enríquez ◽  
Marco A. Chavez ◽  
Ana L. Silba ◽  
Miguel A. Martinez
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Pulse Sequences ◽  
Detailed Comparison ◽  
Coupling Constants ◽  
Dihedral Angles ◽  
Two Dimensional ◽  
Spectral Editing ◽  
One Dimensional ◽  
Inversion Recovery Pulse

The 1H and 13C spectra of mikanokryptin are unambiguously assigned using a variety of one-dimensional nmr experiments (selective homonuclear decoupling, use of inversion–recovery pulse sequences to reveal hidden peaks, and DEPT spectral editing) in conjunction with normal and "long range" two-dimensional heteronuclear correlated experiments. Detailed comparison of vicinal, allylic, and homoallylic 1H—1H coupling constants with dihedral angles determined from an earlier crystal structure determination indicates that solution and solid state configurations are similar.

Synthesis and study of Pt(II)–nitrile complexes. Multinuclear NMR spectra and crystal structures of compounds of the types [Pt(R-CN)Cl3]− and cis and trans-Pt(R-CN)2Cl2

1996 ◽  
Vol 74 (2) ◽  
pp. 144-152 ◽  
Author(s):  
Fernande D. Rochon ◽  
Robert Melanson ◽  
Eryk Thouin ◽  
Corinne Bensimon ◽  
André L. Beauchamp
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Trans Isomer ◽  
Nmr Spectra ◽  
Alkyl Chain ◽  
Coupling Constants ◽  
Trans Isomers ◽  
Multinuclear Nmr ◽  
Cis And Trans ◽  
Bond Trans

Complexes of the type [Pt(R-CN)Cl3]− were synthesized and studied by 1H, 13C, and 195Pt NMR spectroscopies. The 2J(195Pt-13C) coupling constants are about 240 Hz. The signals due to the cyano carbon atoms of the coordinated ligands were observed at higher fields than those of the free ligands. The shielding on the cyano carbon increases as the alkyl chain lengthens and also when the branching increases. The 195Pt signals of all the complexes were observed around −2000 ppm. The crystal structures of (NMe4)[Pt(C3H7-CN)Cl3] (1) and (NMe4)[Pt(p-HO-C6H4-CN)Cl3] (2) were determined. Compound 1 is monoclinic, P21/c, a = 8.384(5), b = 15.336(19), c = 11.759(9) Å, β = 99.52(6)°, Z = 4, R = 0.054, and wR = 0.051. Crystal 2 is tetragonal with a = 16.222(6), c = 12.052(5) Å, Z = 8, R = 0.059, and wR = 0.044. The Pt—CL bond trans to the nitrile ligand is shorter than normal (2.276(3) Å for 1 and 2.264(7) Å for 2) while the two other bonds are normal (2.293(4), 2.287(3) Å for 1 and 2.320(7), 2.275(8) Å for 2). The Pt—N bonds are 1.97(1) Å (1) and 1.92(2) Å (2) and the segments Pt-N≡C-C are linear. Disubstituted compounds were also synthesized and studied by multinuclear NMR. The 195Pt signals of the cis isomers were observed at lower fields than those of the trans isomers (Δ ≈ 65 ppm), while the 13C signals of the cyano carbons of the trans isomers were observed at lower fields than those of the cis compounds (Δ ≈ 0.6 ppm). The cis complexes isomerize to the trans compounds upon heating. The crystal structures of cis-(3) and trans-Pt(C2H5-CN)2Cl2 (4) and also of cis-Pt(p-HO-C6H4-CN)2Cl2 (5) were determined. Crystal 3 is monoclinic, P21/c, a = 7.506(5), b = 9.539(5), c = 14.823(7) Å, β = 92.31(4)°, Z = 4, R = 0.050, and wR = 0.042. The trans isomer 4 is monoclinic with the Pt atom on an inversion centre, P21/c, a = 5.149(4), b = 9.394(8), c = 10.944(10) Å, β = 97.84(7)°, Z = 4, R = 0.017 and wR = 0.020. Finally, compound 5 is triclinic, P-1, a = 7.464(3), b = 10.712(6), c = 12.291(5) Å, α = 75.63(4)°, β = 75.63(4)°, γ = 80.32(4)°, Z = 2, R = 0.045, and wR = 0.056. The Pt—Cl bond distances for the cis isomers are 2.269(5), 2.270(4) Å for 3 and 2.274(2), 2.279(3) Å for 5 while they are 2.289(3) Å for the trans isomer (4). The Pt—N bonds are 1.962(14), 1.988(11) Å (3), 1.972(7), 1.976(7) Å (5) and 1.969(5) Å for 4. Key words: platinum, nitrile, NMR, isomerization, crystal structure.

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