Reactions of enimines with [Cp*RuCl]4:: Half-open ruthenocene and related species incorporating heteroatoms

The reactions of enimines and various silicon, germanium, and tin derivatives with [Cp*RuCl](4) have been investigated and found to lead to a variety of products, depending on the nature of the enimine and the reaction conditions. In general, mixtures of products were obtained comprised of Cp*Ru(eta(5)-azadienyl), Cp*Ru(eta(3)-azadienyl)Cl-2, and Cp*Ru(eta(4)-amino-1,3-diene)Cl complexes. Significant differences in both product preferences and overall yields were observed between the silicon, germanium, and tin reagents, the last typically favoring the eta(5) complexes. The choice of solvent also played a major role, the eta(5) complex being slightly to somewhat disfavored in THF relative to benzene. An attempt to convert an eta(4)-aminodiene complex, Cp*Ru[eta(4)-CH3CHCHC(CH3)CHNH(t-Bu)], to an eta(5)-azadienyl complex through reaction with Ag+ in the presence of K2CO3 led to a mixture of species, which included the desired eta(5) complex as well as an unusual Cp*Ru(eta(3)-dienimine)Cl species, which arose from a formal two-electron oxidation followed by two deprotonations, from the nitrogen center and the internal methyl group. Coordination in this species occurs through the nitrogen center and the distal olefin. Structural confirmation for this species, as well as for one eta(4) and three eta(5) complexes, has been obtained.