Phosphorus-31 NMR studies of several phosphines in the solid state

Abstract

Phosphorus-3 1 NMR powder spectra and high resolution MAS spectra have been obtained for a number of solid phosphines under conditions of high-power proton decoupling and cross-polarization. The principal components of the 3'P chemical shift tensor obtained from static powder spectra or slow MAS spectra are discussed in terms of the known structures of many of the phosphines. The C P / MAS 3 1~ NMR spectra are used to determine the number of crystallographically nonequivalent molecules in thk unit cell. The NMR results are consistent with data available from X-ray diffraction. In one case there is evidence of polymorphism. Mots clis : RMN du 3 1~ de phosphines solides, composantes principales des tenseurs du dCplacement chimique du "P, non-tquivalence cristallographique St partir des spectres rmn C P / MAS du 3'P.

Anisotropy in the31P,63/65Cu Indirect Spin–Spin Coupling and31P Nuclear Shielding Tensors of Linear Copper(I) Phosphines

“…In fact, this appears to be the first report of 31 P chemical shift tensor components in a copper(I) phosphine complex. Qualitatively, the span of the chemical shielding tensor in 1 is significantly smaller than those generally observed in phosphine complexes of transition metals from groups 6 to 10 (16), but is comparable to those of mercury phosphine complexes (17) and free phosphine ligands (18).…”

1H nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and electron delocalization in triphenylphosphine

“…However, the 3 '~ chemical shift tensor is axially symmetric in the solid, consistent with a large amplitude of motion of the phenyl groups about the P-C bonds (3); the inversion barrier is computed as 147 kJ/mol (4) and so inversional motions can be neglected at ambient tempera- 'Author to whom correspondence may be addressed.…”

“…Given that the diamagnetic anisotropy of the P-0, 3.& A P-H4, 5.69 A LCPC, 103" phenyl group, AX = X, , -X, , is negative, and that the 6 scale increases as the shielding decreases, one has eq. [3].…”

“…[3] depends on the anisotropic shift of the protons in benzene, most often taken as 1.50 ppm (27). For TPP it follows that A64 = 0.043 (1 -3 cos2+), angular brackets indicating the expectation value determined by the torsional potential and the temperature.…”

“…[3] and [4] yield A6, as 0.00, (AM1) and 0.00, (STO-3G) as the contributions from the magnetic anisotropy of the two neighbouring phenyl groups to the shielding of the para proton. magnitudes are a consequence of geometry and of the the-C a I z is 7.21 1, implying a AS4 of -0.133, presumably again oretical potentials.…”