Crystal structure of triphenylphosphine sulfide diiodine; the first crystallographically characterised 1 : 1 molecular charge-transfer complex of a tertiary phosphine sulfide with diiodine

摘要

In CH2CI2 solution, Ph3PS and diiodine react to form a molecular 1:1 charge-transfer complex. The complex has been studied in solution using P-31-{H} NMR and UV/VIS spectroscopy. Single-crystal X-ray diffraction and solid-state P-31-{H} NMR studies of Ph3PS . I-2 show that the molecular structure is maintained in the solid phase. The structure of Ph3PS . I-2 is novel and contradicts previous results which indicated that 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 donor power of the Ph3PS towards diiodine. The NMR spectroscopic results on Ph3PS . I-2 and the analogous Ph3PO and Ph3PSe compounds indicate that the stability of the Ph3PE . I-2 complexes increases in the order E = Se > S much greater than 0. [References: 49]