UNPRECEDENTED FORMATION OF ETHYLENE DURING THE SYNTHESIS OF A NB-RH BIMETALLIC COMPLEX - MOLECULAR-STRUCTURE OF CP(2)(')NB(MU-PPH(2))(2)RHC2H4

Reaction between Cp(2)'Nb(PPh(2))(2)Li and (ClRhCOD)(2) (COD = cyclooc tadiene) in tetrahydrofuran followed by the treatment of the reaction product with Et(2)O leads to the unprecedented formation of coordinate d ethylene to give the new heterobimetallic complexes Cp(2)'Nb(PPh(2)) (2)RhC2H4 (Cp = C5H5 (1a); Cp' = C5H4CH3 (1b)) and LiCl. The structure of 1 was established spectroscopically (for 1a), and by X-ray diffrac tion (for 1b). 1b: P-1 (Z=2) with a=10.363(2) Angstrom, b=10.605(2) An gstrom, c=17.629(4) Angstrom alpha=77.11(3)degrees, beta=74.66(3)degre es, gamma=61.51(3)degrees and V=1631.37 Angstrom(3), R=6.07, R(W)=6.38 and G=3.734. The geometry at rhodium is pseudotriangular, the Nb(mu-P -2)RhC2 fragment being almost planar; the Nb-Rh bond distance is 2.869 (2) Angstrom.