ROTATION OF THE CYCLOPENTADIENYL LIGAND IN BIS(MU-CARBONYL)BIS(CARBONYLCYCLOPENTADIENYLIRON)(FE-FE) IN THE SOLID-STATE AS DETERMINED FROM SOLID-STATE DEUTERIUM NMR-SPECTROSCOPY

The motion of the cyclopentadienyl ring in (µ-CO)2[FeCpd(CO)]2 (Cpd= ca. 70% deuteriated η5-cyclopentadienyl) in the solid state has been studied from 100 to 300 K by solid-state deuterium NMR methods. The deuterium spin-lattice relaxation times show that the orientation of the cyclopentadienyl ligands, Cp, is averaged among the five sites of the ring with nearest-neighbor jump rates in the range 1.20 (24) × 107 to 2.4 (5) × 1011 s−1. The activation energy for the process is 12.5 (3) kJ/mol. The kinetic parameters obtained in this work are similar to the values for the reorientation of the cyclopentadienyl ligands in other organometallic compounds as determined with different techniques. The results of this work show that solid-state deuterium NMR spectroscopy uniquely complements existing techniques for the study of the motional properties in organometallic systems. © 1990, American Chemical Society. All rights reserved.