Synthetic, spectroscopic and crystallographic studies of heterofunctional diphosphazane ligands

New unsymmetrical diphosphazanes of the type X(2)PN(Pr-i)PYY' {X = Ph, YY' = O2C12H8 (1a), O2C20H12 (1b); X = Ph, Y = Ph, Y' = OC(6)H(4)Me-($) under bar 4(1c), OC6H4Br-($) under bar 4 (1d), OC(6)H(3)Me(2)-($) under bar 3,($) under bar 5 (1e), N2C3H3 (1f), N(2)C(3)HMe(2)-($) under bar 3,($) under bar 5 (1g), OC5H5N-2 (1h)} are prepared and converted into their mono- and di-oxides or sulfides. These can function as heterofunctional ligands through P, S, N or O donor sites. These compounds have been characterized by NMR spectroscopic studies. Variable temperature P-31{H-1} NMR measurements on some of these compounds reveal the presence of different types of conformers in solution. Single crystal X-ray diffraction studies have been carried out for Ph(2)P(S)N(Pr-i)PPh(N(2)C(3)HMe(2)-($) under bar 3,($) under bar 5)(2g) and Ph(2)P(O)N(Pr-i)P(O)Ph(OC5H4N-2) (5h).