eta(5)-imidazolato complexes of ruthenium

The imidazolato complexes [Cp*Ru(mu-eta (1):eta (1)-Ph2C3HN2)](3), Cp*Ru(et a (5)-Ph2C3HN2), and Cp*Ru(eta (5)-Me2C3HN2) have been prepared and charact erized. The Latter complexes represent the first structural documentation o f the eta (5)-imidazolato ligand coordination, mode to any metal. [Cp*Ru(mu -eta (1):eta (1)-Ph2C3HN2)](3) converts to Cp*Ru(eta (5)-Ph2C3HN2) upon hea ting in tetrahydrofuran, demonstrating that the eta (5)-imidazolato ligand is thermodynamically preferred over the mu-eta (1):eta (1)-ligand in the Cp *Ru(II) system.