STUDIES OF THE BONDING IN IRON(II) CYCLOPENTADIENYL AND ARENE SANDWICH COMPOUNDS .3. C-13 NUCLEAR-MAGNETIC-RESONANCE AND FE-57 MOSSBAUER SPECTROSCOPIC STUDIES ON TA-CYCLOHEXADIENYL)(ETA-CYCLOPENTADIENYL)]IRON(II) COMPLEXES

A series of [Fe(eta-C5H4X)(eta-C6H7-nXn)] (X = H or Me, n = 0-6) compl exes has been prepared. A detailed analysis of their C-13 NMR spectra is presented, the assignments being confirmed using distortionless enh ancement by polarisation transfer (DEPT) techniques. The co-ordination shift of the cyclohexadienyl ligand shifts are not uniform and these anomalies are discussed in terms of possible bonding schemes. The effe ct of substitution by chlorine and methyl groups is also included. For the case where X = Me, evidence is presented for the occurrence of co nformational isomers due to restricted rotation of the ligands. The Fe -57 Mossbauer parameters are reported as well as a temperature-depende nce study. The results are discussed in terms of the somewhat distorte d nature of the cyclohexadienyl ligand in these complexes.