Cycloheptatrinyl bridged heterobimetallic complexes: synthesis, fluxional behaviour and X-ray crystal structure of syn-[(μ-η3;η2-C7H7)Fe(CO)3Pt(η2, σ1-C8H12C5H5)]

The reaction of [(η3C7H7)Fe(CO)3]- with [(η4-C8H12)(η5-C 5H5)Pt]+ leads to the formation of syn-[(μ-η3;η2-C7H7)-Fe(CO)3Pt)η2,σ1-C8H12-C5H5)] (1), a bridged cycloheptatrienyl complex with an FePt bond. In solution two structural isomers of 1 are present ini roughly the same concentration, whereas in the solid only one isomer is detected. Both isomers are fluxional and undergo ring whizzing of the C7H7 ring. The slow-exchange limiting NMR spectrum of the cycloheptatrienyl unit cannot be reached even at low temperature (∼173 K). The C7H7 ring has an uncoordinated double bond and the cyclopentadienyl unit is linked to the C8H12 ring through an sp2 carbon; the resulting cyclooctenyl unit is coordinated η2,σ1 to platinum. The C5H5 transfer, mediated by platinum, can be of interest in the synthesis of the skeleton of natural occurring products. Crystal data for syn-[(μ-η3;ν2-C7h7 )Fe(CO)3Pt(ν2,σ1-C8 H12-C5H5)]: monoclinic, space grou[ C2/C (No. 15), a = 45.197(6), b=13.306(1), c=7.509(1) A ̊, β=92.96(1)°, V=4509.8(9) A ̊3, Z=8, R=0.033, Rw=0.080. © 1995.