The reaction of tertiary aryl phosphites with diiodine at ambient temperatures; structural characterisation of the tertiary phosphite tetraiodides (PhO)(3)PI4, (4-MeC6H4O)(3)PI4 and (2,4-(Bu2C6H3O)-C-t)(3)PI4

The reaction of the tertiary phosphites (RO)(3)P (R = Ph, 4-MeC6H4, 4-(BuC6 H4)-C-t, 2,4-(Bu2C6H3)-C-t, 2,6-Me2C6H3, 2,4,6-Me3C6H2 or 2-PhC6H4) with on e and two mole equivalents of diiodine has been investigated. In all cases the tetra-iodide compounds (RO)(3)PI4 were isolated regardless of the stoic hiometry employed. The three compounds (RO)(3)PI4 (R = Ph, 4-MeC6H4 or 2,4- (Bu2C6H3)-C-t) have been crystallographically characterised for comparative purposes and represent the first examples of crystal structures for compou nds of this formula. The structural characterisation of these compounds ill ustrates the structural dependence of (RO)(3)PI4 compounds on R. For (RO)(3 )PI4 (R = Ph or 2,4-(Bu2C6H3)-C-t) the compounds exist as discrete molecula r species whereas, for R = 4-MeC6H4 the triiodide fragments of discrete mol ecules link via long-range I-I interactions to form a dimer. Additionally, d(I-I) for the (RO)(3)PI and I-3 fragments is sensitive to R, being 3.227(1 ) Angstrom for (2,4-(Bu2C6H3O)-C-t)(3)PI4 and 3.3888(7) Angstrom for (PhO)( 3)PI4. In contrast to the analogous R3PI4 compounds, which show great varia tion in delta in their P-31-{H-1} NMR spectra depending on R, the (RO)(3)PI 4 compounds described all exhibit quite similar delta values irrespective o f R.