TRANSITION-METAL COMPLEXES .7. [(ETA(5)-CP)NI(PET(3))](2), A DINUCLEAR ORGANOMETALLIC COMPLEX WITH AN UNBRIDGED NI-NI BOND - STRUCTURE AND HETERONUCLEAR COMPLEXES THEREOF

[(eta(5)-Cp)Ni(PEt(3))](2) (1) has been synthesized by reacting (eta(5 )-Cp)Ni(PEt(3))Cl with activated magnesium. 1 contains an unbridged ni ckel-nickel bond. Reaction of 1 with elemental sulfur yields the clust ers [(eta(5)-Cp)(2)(PEt(3))(2)(mu(3)-S)Ni-3] (2) and [(eta(5)-Cp)(PEt( 3))Ni(mu-S)Ni(eta-Cp)](2) (3). The homologous selenium compound [(eta( 5)-Cp)(PEt(3))Ni(mu-Se)Ni(eta(5)-Cp)l(2) (4) has been obtained by the reaction of 1 with elemental selenium. 1 reacts with tellurium by inse rtion to yield {[(eta(5)-Cp)Ni(PEt(3))]Te-2} (5). Tin(II) chloride can also be inserted into the nickel-nickel bond of 1 to give {[(eta(5)-C p)Ni(PEt(3))]2SnCl2} (6). Both chlorine atoms in 6 react with alkyllit hium to give compounds Of the type {[(eta(5)-Cp)Ni(PEt(3))](2)SnR(2)} (7) (a: R=Me, b: R=n-Bu). The reaction of 6 with activated magnesium y ields {[(eta(5)-Cp)Ni(PEt(3))]3SnCl} (8). Crystal structures of 1, 2, 3, 5, 6 and 8 have been determined.