Preparation and Properties of Phosphaethynes Bearing Bulky Aryl Groups with Electron-Donating Substituents at the Para Position

Phosphaethynes bearing a 2,6-di-tert-butyl-4-(dimethylamino)phenyl, 2,6-di-tert-butyl-4-methoxyphenyl, or 2,6-di-tert-butylphenyl group were prepared. A 31P NMR spectroscopic investigation of
the chemical shifts indicated that electron-donating groups at the para position cause shifts to a
higher field. Bathochromic shifts caused by the electron-donating groups were apparently observed
in UV−vis spectra. The structure of 2-[2,6-di-tert-butyl-4-(dimethylamino)phenyl]-1-phosphaethyne
was analyzed by X-ray crystallography.