Several new fluxional molecules containing substituted 1,2,1-trihaptobenzyl groups bound to the (C5H5)Mo(CO)2 and (C5H5)W(CO)2 residues have been prepared and their proton magnetic resonance spectra studied with the objective of elucidating the pathway and evaluating the activation parameters concerned in the fluxional behavior of this class of molecules. The molecules are less difficult to prepare and more stable than previously reported. The chief qualitative conclusion, derived from the study of the 3,5-diisopropylbenzyl compound, is that the (C5H5)Mo(CO)2 residue has access to all four equivalent (including enantiomorphically related) positions of attachment to the benzyl group. A plausible pathway would be via a monohapto- (i.e., σ-) C6H5CH2MoiC5H5)(CO)2 intermediate, in which rotation about the C1-C7 bond of the benzyl group can occur.
ASJC Scopus subject areas
- Colloid and Surface Chemistry