Cycloheptatrinyl bridged heterobimetallic complexes: synthesis, fluxional behaviour and X-ray crystal structure of syn-[( μ- η3; η2-C 7H 7)Fe(CO) 3Pt( η2, σ1-C 8H 12C 5H 5)

Abstract

The reaction of [( η 3C 7H 7)Fe(CO) 3] − with [( η 4-C 8H 12)( η 5-C 5 H 5)Pt] + leads to the formation of syn-[( μ- η 3; η 2-C 7H 7)-Fe( CO) 3Pt) η 2, σ 1-C 8H 12-C 5H 5)] ( 1), a bridged cycloheptatrienyl complex with an FePt 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 C 7H 7 ring. The slow-exchange limiting NMR spectrum of the cycloheptatrienyl unit cannot be reached even at low temperature (∼173 K). The C 7H 7 ring has an uncoordinated double bond and the cyclopentadienyl unit is linked to the C 8H 12 ring through an sp 2 carbon; the resulting cyclooctenyl unit is coordinated η 2, σ 1 to platinum. The C 5H 5 transfer, mediated by platinum, can be of interest in the synthesis of the skeleton of natural occurring products. Crystal data for syn-[( μ- η 3; ν 2-C 7h 7)Fe(CO) 3Pt( ν 2, σ 1-C 8H 12-C 5H 5)]: 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, R w =0.080 .