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Chen F, Ma G, Bernard GM, Cavell RG, McDonald R, Ferguson MJ, Wasylishen RE: Solid-State (115) In and (31) P NMR Studies of Triarylphosphine Indium Trihalide Adducts. J Am Chem Soc. 2010 Mar 29.
Solid-state (115) In and (31) P NMR spectroscopy, relativistic density functional theory (DFT) calculations, and single-crystal X-ray diffraction were used to investigate a series of triarylphosphine indium (III) trihalide adducts, X (3) In (PR (3)) and X (3) In (PR (3))(2) (X = Cl, Br or I; PR (3) = triarylphosphine ligand). The electric field gradient tensors at indium as well as the indium and phosphorus magnetic shielding tensors and the direct and indirect (115) In-(31) P spin-spin coupling were characterized; for complexes possessing a C (3) symmetry axis, the anisotropy in the indirect spin-spin coupling, DeltaJ ((115) In,(31) P), was also determined. The (115) In quadrupolar coupling constants, C (Q)((115) In), range from +/-1.25 +/- 0.10 to -166.0 +/- 2.0 MHz. For any given phosphine ligand, the indium nuclei are most shielded for X = I and least shielded for X = Cl, a trend also observed for other group-13 nuclei in M (III) complexes. This experimental trend, attributed to spin-orbit effects of the halogen ligands, is reproduced by the DFT calculations. The spans of the indium magnetic shielding tensors for these complexes, delta (11) - delta (33), range from 40 +/- 7 to 710 +/- 60 ppm; those determined for phosphorus range from 28 +/- 1.5 to 50 +/- 3 ppm. Values of (1) J ((115) In,(31) P) range from 550 +/- 20 to 2500 +/- 20 Hz. For any given halide, the (1) J ((115) In,(31) P) values generally increase with increasing basicity of the PR (3) ligand. Calculated values of (1) J ((115) In,(31) P) and DeltaJ ((115) In,(31) P) duplicate experimental trends and indicate that both the Fermi-contact and spin-dipolar Fermi-contact mechanisms make important contributions to the (1) J ((115) In,(31) P) tensors. |
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