The allenylidene complex [Ru(η5-C5H5)(CCCPh2)(CO)(PPri3)]BF4 (1) reacts with dicyclohexylcarbodiimide to give the iminiumazetidinylidenemethyl complex (2), as a 4:1 mixture of isomers Z (2a) and E (2b). The structure of 2a was determined by an X-ray investigation, revealing a Ru−C distance of 2.070(4) Å. Treatment of the isomeric mixture of 2 with sodium methoxide in tetrahydrofuran at room temperature affords the iminoazetidinylidenemethyl complex (6), which reacts with HBF4·OEt2 to give (7), as a result of the protonation of the exocyclic nitrogen atom of the unsaturated η1-carbon ligand of 6. In the solid state and in solution at low temperature, complex 7 is stable. However, in solution at room temperature, complex 7 evolves into (8), which reacts with sodium methoxide in tetrahydrofuran at room temperature to give the hexahydroquinolinylidenemethyl complex (9), as a result of the deprotonation of the endocyclic nitrogen atom of 8. The structure of 9 was also determined by an X-ray investigation, revealing, in this case, a Ru−C distance of 2.113(4) Å. The formation of the azetidine and hexahydroquinoline skeletons of the ligands of these compounds is discussed.

We thank the DGES (Project PB-95-0806, Programa de Promoción General del Conocimiento) for financial support.

Peer reviewed