TRANSITION METAL COMPLEXES IN ORGANIC-SYNTHESIS - 41 - SYNTHESIS, MOLECULAR-STRUCTURE, FLUXIONAL BEHAVIOR, AND TRICARBONYLIRON TRANSFER-REACTIONS OF (ETA(4)-1-AZABUTA-1,3-DIENE)TRICARBONYLIRON COMPLEXES

The (eta(4)-1-azabuta-1,3-diene)tricarbonyliron complexes 10 are easil y prepared in high yield by condensation of the corresponding arylamin es 7 with the cinnamaldehydes 8 and subsequent ultrasound-promoted com plexation of the resulting 1-azabuta-1,3-dienes 9 with nonacarbonyldii ron. The complexes 10 are shown to represent excellent reagents for th e transfer of the tricarbonyliron fragment onto cyclohexa-1,3-diene (1 a). The structural characterization for the complexes 10 is achieved b y IR, H-1-NMR, and C-13-NMR spectroscopy, as well as X-ray crystallogr aphy of 10b, 10c, and 10l. Using variable temperature C-13-NMR spectro scopy the fluxionality of the complexes 10a, 10b, 10c, 10e, and 2 is i nvestigated and the activation barrier for the turnstile rotation of t he tricarbonyliron fragment is determined. The transfer reaction and t he structural factors influencing the transfer of the tricarbonyliron fragment are extensively investigated.