157. Intramolecular Dynamics of Five-coordinate Iron Carbonyl Complexes with Olefinic Ligands as Studied by Variable-Pressure (1)H-NMR Spectroscopy

Article abstract of DOI:10.1002/hlca.19880710609

Variable-pressure (1)H-NMR spectroscopy has been used to study the fluxionality of some five-coordinated Fe complexes in solution.For , the CO site exchange is known (by analogy with to be a non-dissociative process, and an activcation volume of ca. 0 cm³.mol^-1 was indeed obtained.However, for hept-2-ene)>(PPh3)>, the activation volume of +5 cm³ mol^-1 suggests that an unprecedented dissociation process is responsible for the CO site exchange.The molecular structure of was ascertained by single-crystal X-ray diffractometry.The crystals are triclinic, space group P1<*>, a=9.606(3), b=16.795(2), c=7.743(8) Angstroem, α=97.83(4), β=109.63(4), γ=83.37(2) deg.The structure determination has shown that the complex possesses a tetragonal pyramidal coordination, with the endocyclic C=C bond and PPh3 occupying basal sites.