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

Abstract

Abstract The synthesis of dimetallic olefin complexes of the type L 1 M 1 C 7 H 7 M 2 L 2 (M 1 = Fe, Co, Rh; M 2 = Rh, Ir, Pd; L 1 = CO, C 5 H 5 ; L 2 = diene, allyl, P(OR) 3 ) is described. The fluxional structures were investigated by 13 C‐, 57 Fe‐ and 103 Rh‐NMR.‐spectroscopy, and a cisoid dimetallic coordination, including a (metal, metal)‐bond, can be deduced for the C 7 H 7 ‐ring. 57 Fe‐ and 103 Rh‐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 13 C‐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°.