STUDIES OF A RELUCTANT LIGAND - AN X-RAY CRYSTALLOGRAPHIC AND NMR SPECTROSCOPIC ANALYSIS OF (OC)(5)W(ETA(1)-PPH2CH2PPH2) AND ITS (OC)(5)W(MU-PPH2CH2PPH2)W(CO)(5) DERIVATIVE
Jw. Benson et al., STUDIES OF A RELUCTANT LIGAND - AN X-RAY CRYSTALLOGRAPHIC AND NMR SPECTROSCOPIC ANALYSIS OF (OC)(5)W(ETA(1)-PPH2CH2PPH2) AND ITS (OC)(5)W(MU-PPH2CH2PPH2)W(CO)(5) DERIVATIVE, Organometallics, 17(19), 1998, pp. 4275-4281
Tungsten pentacarbonyl complexes, (OC)(5)W(eta(1)-PPh2CH2PPh2) (1) and
(OC)(5)W(mu-PPh2CH2PPh2)W(CO)(5) (2), have been synthesized from (OC)
(5)WNH2Ph and Ph2PCH2PPh2 in toluene, and their solid-state structures
have been determined by single-crystal X-ray diffraction. The lone pa
ir of electrons on the dangling phosphine in 1 is oriented toward the
W(CO)(5) unit in the solid state, and C-13{H-1} and P-31{H-1} NMR data
suggest that this conformation may also be dominant in solution. Phos
phorus-phosphorus coupling in 1 ((2)J(PP) = 106 Hz) is significantly l
arger than in any previously reported complex of Ph2PCH2PPh2 and is hi
ghly dependent on changes in temperature and solvent. Also observed is
an unprecedented long-range phosphorus-carbon coupling ((4)J(PC) = 3.
0 Hz) between the dangling phosphine and the equatorial carbonyl carbo
ns of 1, which is attributed to a conformational and/or ''through-spac
e'' enhancement. On the basis of the structural and spectral data, the
reluctance of 1 to react with (OC)(5)WNH2Ph to give 2 is explained in
terms of the substantial ligand conformation change required.