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.