CYCLOHEPTATRIENYL BRIDGED HETEROBIMETALLIC COMPLEXES - SYNTHESIS, FLUXIONAL BEHAVIOR AND X-RAY CRYSTAL-STRUCTURE OF A(2)-C7H7)FE(CO)(3)PT(ETA(2),SIGMA(1)-C8H12-C5H5)]

The reaction of [(eta(5)-C7H7)Fe(CO)(3)](-) with [(eta(4)-C8H12)(eta(5 )-C5H5)Pt](+) leads to the formation of C7H7)Fe(CO)(3)Pt(eta(2),sigma( 1)-C8H12-H-12-C5H5)] (1), a bridged cycloheptatrienyl complex with an Fe-Pt bond. In solution two structural isomers of 1 are present in rou ghly the same concentration, whereas in the solid only one isomer is d etected. Both isomers are fluxional and undergo ring whizzing of the C 7H7 ring. The slow-exchange limiting NMR spectrum of the cycloheptatri enyl unit cannot be reached even at low temperature (similar to 173 K) . The C7H7 ring has an uncoordinated double bond and the cyclopentadie nyl unit is linked to the C8H12 ring through an sp2 carbon; the result ing cyclooctenyl unit is coordinated eta(2),sigma(1) to platinum. The C5H5 transfer, mediated by platinum, can be of interest in the synthes is of the skeleton of natural occurring products. Crystal data for (2) -C7H7)Fe(CO)(3)Pt(eta(2),sigma(1)-C8H12-C5H5)]: monoclinic, space grou p C2/c (No.15), a=45.197(6),b=13.306(1), c=7.509(1) Angstrom, beta=92. 95(1)degrees, V=4509.8(9) Angstrom(3), Z=8 R=0.033, R(w)=0.080.