Dimetallic Complexes with Bridging Seven‐membered Cycloolefins. Synthesis, Multinuclear NMR.‐Spectroscopic Properties and Structure

Abstract
The synthesis of dimetallic olefin complexes of the type L1M1C7H7M2L2 (M1 = Fe, Co, Rh; M2 = Rh, Ir, Pd; L1 = CO, C5H5; L2 = diene, allyl, P(OR)3) is described. The fluxional structures were investigated by 13C‐, 57Fe‐ and 103Rh‐NMR.‐spectroscopy, and a cisoid dimetallic coordination, including a (metal, metal)‐bond, can be deduced for the C7H7‐ring. 57Fe‐ and 103Rh‐chemical shifts give indications for the charge distribution in the 34e‐complexes. The homodimetallic complex (Cp)Rh(tropone)Rh(Cp) (13, Cp = cyclopentadienyl) and the corresponding 2‐methoxytropone complex 14 were synthesized in addition to the above mentioned complexes. A fluxional bis(1‐3‐η‐allyl)‐coordination of the two Rh‐atoms was derived from the temperature‐dependent 13C‐NMR.‐spectra. A spin simulation of the (Cp)‐multiplets of 12 and 13 yields information about (Rh, Rh)‐spin‐coupling which amounts to ≈5 Hz at 30°.