The synthesis and structural characterisation of some azo-containing phosphine chalcogenides and comparison to non-phosphorus-containing analogues

p-HO-Ph(Ph2)P(E) (E=S, 1b, Se, 1c) reacts with the diazonium salts [4-R-PhN=N][BF4] (R=H, Me, Et, iPr, tBu, NMe2, NO2) to afford the new compounds [1-HO-2-(4-R-PhN=N)-4-Ph2P(E)C6H3] (E=S, R=H, 2a; Me, 2b; Et, 2c; iPr, 2d; tBu, 2e; NMe2, 2f; NO2, 2g; E=Se, R=H, 2h; Me, 2i) in acceptable yield. Similarly m-HO-Ph(Ph2)P(S) 3 reacts with two molar equivalents of the diazonium salts [4-R-PhN=N][BF4] (R=H, Me, NMe2, NO2) to give the new compounds 1-HO-2,4-(4-R-PhN=N)-3-Ph2P(S)-C6H2 4a-d (R=H, 4a; Me, 4b; NMe2, 4c; NO2, 4d). All of the new compounds have been characterised by elemental analysis, 1H, 31P-{1H}, 13C-{1H}-NMR spectroscopy and in selected cases UV-visible spectroscopy. The selectivity in the substitution reactions of 3 with the diazonium salts is influenced not only by the steric bulk of the Ph2PS moiety but by the ortho-effect too. These data have been compared to those obtained from analogous coupling reactions between m-cresol and one and two molar equivalents of [4-Me-PhN=N][BF4] which afford 1-HO-3-CH3-4-(4-Me-PhN=N)C6H3 5 and 1-HO-3-CH3-2,4-(4-Me-PhN=N)C6H2 6 respectively. The compounds 2b·0.55CH2Cl2·0.2C6H 14, 4b·CH2Cl2, 5 and 6b have been further characterised by X-ray crystallography.