Neutral Ru(η⁵-pyrrole) Complexes. Synthesis and Structure of Diazaruthenocenes and Ru(1-3:5,6-η⁵-C₈H₁₁)(η⁵-pyrrole) Complexes

The synthesis of metal complexes with anionic η⁵-pyrrole ligands is generally complicated by the free nitrogen lone pair. Methods are reported for the synthesis of two types of neutral η⁵-tetramethylpyrrolyl (NC₄Me₄) ruthenium complexes. Ru(η⁵-NC₄Me₄)₂ is prepared from (Ph₃P)₃RuCl₂ and lithium tetramethylpyrrolide in refluxing THF. A chiral diazaruthenocene with C₂ symmetry is prepared from 2,3-dimethyl-4,5,6,7-tetrahydroindole. Attempts to prepare diazaruthenocenes from [Ru(η⁴-C₈H₁₂)Cl₂]_x led to deprotonation of the COD ligand to form a complex Ru(1-3:5,6-η⁵-C₈H₁₁)(η⁵-NC₄Me₄) isoelectronic with Ru(η⁵-NC₄Me₄)₂.