ALKYNE INSERTIONS INTO THE SIGMA-PD-C(SP(2), FERROCENE) BOND OF CYCLOPALLADATED COMPLEXES CONTAINING SCHIFF-BASES DERIVED FROM FERROCENE - CRYSTAL-STRUCTURES OF [PD([(ETC=CET)(2)(ETA(5)-C5H3CR=N-CH(2)PH)]FE(ETA(5)-C5H5))CL] (R=H OR ME)

Reactions of di-mu-chloro-bridged cyclopalladated compounds [{Pd[(eta(5)-C(5)H(3)CR = NR')Fe(eta(5)-C5H5)](mu-Cl)}(2)] (R = H, Ph or Me, R' = CH(2)Ph; R = H, R' = CH(2)CH(2)Ph) with alkynes R '' C = CR '' (R '' = Et or Ph) have been studied. In all cases these reactions produce nine-membered metallocycles [Pd{[(R '' C = CR '')(2)(eta(5)-C(5)H(3)CR = N R')]Fe(eta(5)-C5H5)}Cl] (R '' = Et or Ph), which arise from a double insertion of the alkyne. Compounds [Pd{[(EtC = CEt)(2)(eta(5)-C(5)H(3)CR = NCH(2)Ph)]Fe(eta(5)-C5H5)}Cl] (R = H 4a or Me 4d) have been characterized structurally. Complex 4a is monoclinic, space group C2/c, with a = 30.783(4). b = 11.320(2), c =20.181(3) Angstrom and beta = 127.23(3)degrees; compound 4d is also monoclinic space group P2/a, with a = 20.308(4), b =11.075(2), c =12.565(2) Angstrom and beta = 92.01(3)degrees. These structural studies confirm the existence of a bicyclic system arising from the fusion of a nine-membered ring and the C5H3 moiety of the ferrocenyl moiety. The differences observed in the reactivity of the sigma(Pd-C-sp2,C- ferrocene) bond in the cyclopalladated compounds [{Pd[eta(5)C(5)H(3)CRFe(eta(5)-C5H5)](mu-Cl)}(2)] (R = H, Ph or Me) and in [{Pd[(eta(5)-C(5)H(3)CH(2)NMe(2))Fe(eta(5)-C5H5)](mu-Cl)}(2)] can be explained in terms of the electron donor ability of the chelated ligand. This. property is reflected mainly in the redox potential of the iron centre.