Two tris(3,5-disubstituted phenyl)phosphines and their isostructural P(V) oxides

Thumbnail Image
Hill, Nathan D. D.
Boeré, René T.
Journal Title
Journal ISSN
Volume Title
International Union of Crystallography
The crystal structures of tris(3,5-dimethylphenyl)phosphine (C24H27P), (I), tris(3,5-dimethylphenyl)phosphine oxide (C24H27OP), (II), tris(4-methoxy-3,5dimethylphenyl)phosphine (C27H33O3P), (III), and tris(4-methoxy-3,5-dimethylphenyl)phosphine oxide (C27H33O4P), (IV), are reported. The strucure of (III) has been described before [Romain et al. (2000). Organometallics, 19, 2047–2050], but it is rereported here on the basis of modern area-detector data and to facilitate comparison with the other structures reported here. Compounds (I) and (II) crystallize isostructurally in P21/c. Similarly, (III) and (IV) crystallize isostructurally in Pbca. The conformations of (I) and (II) in the solid state deviate strongly from helical, whereas those of (III) and (IV) are found to be closer to an ideal threefold rotational symmetry. The pyramidality indices, P(C—P—C), are 305.35 (16), 317.23 (15), 307.2 (4) and 318.67 (18) for (I), (II), (III) and (IV), respectively. Each is found to be more pyramidal than Ph3P or Ph 3PO. Hybrid DFT calculations incorporating terms for dispersion provide evidence that the causes of the increased pyramidality, despite the 3,5dimethyl group substitution, include dispersion interactions. The calculated P(C—P—C) values are 304.8 for both (I) and (III) and 317.4 for both (II) and (IV), with no difference arising from the substitution at ring position 4.
Sherpa Romeo green journal. Open access Article. Creative Commons Attribution License (CC-BY) applies.
Crystal structure , Phosphane , Diayl-phosphorylbenzene , Phosphine oxide , π-stacking , Packing forces , Conformation
Hill, N. D. D. & Boeré, R. T. (2018). Two tris(3,5-disubstituted phenyl)phosphines and their isostructural P(V) oxides. Acta Crystallographica Section E, Crystallographic Communications, E74, 889-894. ica