Multiply substituted cyclopentadienyl metal complexes: I. Solid-state and solution conformational studies on (η5-C5Me4R) Fe(CO) (L) I (R = H, tBu)

Article abstract of DOI:10.1016/0022-328X(95)05865-M

A series of (η⁵-C₅Me₄R)Fe(CO)(L)I complexes (R = H, L = P(OMe)₃, PMe₃, P(OⁱPr)₃, PPh₃, P(O-o-tol)₃, PBz₃; R = ^tBu, L = P(OMe)₃, P(OPh)₃, PPh₃) have been synthesized and characterized by spectroscopic techniques (IR, ¹H and ¹³C NMR). NOE spectroscopy was used to ascertain that the L group resided, on average, away from the bulky ring substituents. Thus, for R =^tBu, L was displaced away from the ^tBu group, while, for R = H, L resided close to the H group. Crystal structure determinations were performed on (η⁵-C₅Me₄H)Fe(CO)(PPh₃)I (1) and (η⁵-C₅Me^t₄Bu)Fe(CO)[P(OPh)₃]I (2). Both structures showed expected bond angle and bond length trends. The arrangement of the ligand set (L, CO, I) below the cyclopentadienyl ring in the solid state was the same as that found in solution. These results again reveal the importance of the steric effects associated with the cyclopentadienyl ring substituents on the properties of cyclopentadienyl-metal complexes in both the solution and solid states.