An Investigation of 1:1 Adducts of Gallium Trihalides with Triarylphosphines by Solid‐State 69/71Ga and 31P NMR Spectroscopy. Issue 8 (10th January 2013)

• Record Type: Journal Article
• Authors: Chen, Fu; Ma, Guibin; Bernard, Guy M.; Wasylishen, Roderick E.; Cavell, Ronald G.; McDonald, Robert; Ferguson, Michael J.
• Is Part Of: Chemistry. Volume 19:Issue 8(2013)
• Page Start: 2826
• Page End: 2838
• Publication Date: 2013-01-10
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201202954
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Several 1:1 adducts of gallium trihalides with triarylphosphines, X<sub>3</sub>Ga(PR<sub>3</sub>) (X=Cl, Br, and I; PR<sub>3</sub>=triarylphosphine ligand), were investigated by using solid‐state <sup>69/71</sup>Ga and <sup>31</sup>P NMR spectroscopy at different magnetic‐field strengths. The <sup>69/71</sup>Ga nuclear quadrupolar coupling parameters, as well as the gallium and phosphorus magnetic shielding tensors, were determined. The magnitude of the <sup>71</sup>Ga quadrupolar coupling constants (<italic>C</italic><sub>Q</sub>(<sup>71</sup>Ga)) range from approximately 0.9 to 11.0 <sc>MHz</sc>. The spans of the gallium magnetic shielding tensors for these complexes, <italic>δ</italic><sub>11</sub>−<italic>δ</italic><sub>33</sub>, range from approximately 30 to 380 ppm; those determined for phosphorus range from 10 to 40 ppm. For any given phosphine ligand, the gallium nuclei are most shielded for X=I and least shielded for X=Cl, a trend previously observed for In<sup>III</sup>–phosphine complexes. This experimental trend, attributed to spin‐orbit effects of the halogen ligands, is reproduced by DFT calculations. The signs of <italic>C</italic><sub>Q</sub>(<sup>69/71</sup>Ga) for some of the adducts were determined from the analysis of the <sup>31</sup>P NMR spectra acquired with magic angle spinning (MAS). The <sup>1</sup><italic>J</italic>(<sup>69/71</sup>Ga, <sup>31</sup>P) and Δ<italic>J</italic>(<sup>69/71</sup>Ga, <sup>31</sup>P) values, as well as their signs, were also determined; values of <sup>1</sup><italic>J</italic>(<sup>71</sup>Ga, <sup>31</sup>P) range from approximately 380 to 1590 Hz. Values of <sup>1</sup><italic>J</italic>(<sup>69/71</sup>Ga, <sup>31</sup>P) and Δ<italic>J</italic>(<sup>69/71</sup>Ga, <sup>31</sup>P) calculated by using DFT have comparable magnitudes and generally reproduce experimental trends. Both the Fermi‐contact and spin‐dipolar Fermi‐contact mechanisms make important contributions to the <sup>1</sup><italic>J</italic>(<sup>69/71</sup>Ga, <sup>31</sup>P) tensors. The <sup>31</sup>P NMR spectra of several adducts in solution, obtained as a function of temperature, are contrasted with those obtained in the solid state. Finally, to complement the analysis of NMR spectra for these adducts, single‐crystal X‐ray diffraction data for Br<sub>3</sub>Ga[P(<italic>p</italic>‐Anis)<sub>3</sub>] and I<sub>3</sub>Ga[P(<italic>p</italic>‐Anis)<sub>3</sub>] were obtained.</p> </abstract>