Reaction of [NiCp(PPh3)Cl] with E(SiMe3)2; the Structures of [Ni4Se2Cp4] and [Ni4E2Cp4(PPh3)2] (E = Se, Te)

X‐ray structure analyses of 1a and 2 indicate the presence of NiNi bonds in 1 and the absence of such bonds in 2. The complexes 1 and 2 are formed together in the reaction of [NiCp(PPh3)Cl] with E(SiMe3)2 (a, E = Se; b, E = Te). But 2 is also accessible from 1 and PPh3. In this reaction, all bonds of the square Ni4‐cluster of 1 are broken, and the μ4‐E bridges become μ3‐E bridges. equation image