CRYSTAL-STRUCTURE OF TRIPHENYLPHOSPHINE SULFIDE DIIODINE - THE FIRST CRYSTALLOGRAPHICALLY CHARACTERIZED 1 1 MOLECULAR CHARGE-TRANSFER COMPLEX OF A TERTIARY PHOSPHINE SULFIDE WITH DIIODINE/

In CH2CI2 solution, Ph3PS and diiodine react to form a molecular 1:1 c harge-transfer complex. The complex has been studied in solution using P-31-{H} NMR and UV/VIS spectroscopy. Single-crystal X-ray diffractio n and solid-state P-31-{H} NMR studies of Ph3PS . I-2 show that the mo lecular structure is maintained in the solid phase. The structure of P h3PS . I-2 is novel and contradicts previous results which indicated t hat a 1:1 (Ph3PS:I-2) complex could not be isolated in the solid state . The I-I distance [2.823(1) Angstrom] and the S-I distance [2.753(2) Angstrom] in Ph3PS . I-2 are comparable with those in charge-transfer complexes of related sulfur donors. However, the I-I distance in Ph3PS . I-2 is shorter than that in Ph3PSe . I-2 reflecting the weaker dono r power of the Ph3PS towards diiodine. The NMR spectroscopic results o n Ph3PS . I-2 and the analogous Ph3PO and Ph3PSe compounds indicate th at the stability of the Ph3PE . I-2 complexes increases in the order E = Se > S much greater than 0.