INFRARED AND RAMAN STUDY OF NEW TYPES OF ROTATIONAL ISOMERISM IN ORGANOMETALLIC COMPOUNDS OF TRANSITION METALS

Author Institution: A.N. Nesmeyanov Institute of Organoelement compounds, Russian Academy of ScienceA hindered internal rotation in the molecules of organometallic compounds of transition metals in organic and liquified noble gas solutions was studied using FTIR and Raman spectroscopy in a wide temperature range. It was demonstrated that rotational exist due to the internal rotation about single bonds between the transition metal and carbon atoms (in ``staircase” carbonyl pi-complexes of Fe, Mn, Cr, Mo, W), transition metal and non-transition element (in the complexes Cp(Co)2Fe$M^{\prime}$ X2R and [Cp(Co)2Fe]2$M^{\prime}$X2, $M^{\prime}$ = Ge, Sn Cp = cyclopentadienyl), and between two transition metals (in binuclear complexes [Cp(CO)2M]2), M = Fe, Ru). The rotation of the M[CO)3- fragment was found in the ferrol type clusters of Ru and Re, where this group is pi-coordinated to the double bonds of metallacyclopentadienyl ring. The influence of different factors on the energy difference between rotational and on the rotational barriers is discussed