Synthesis of 2-pyrrolyl complexes of ruthenium and osmium via hydrolysis of a chloro(pyrrolyl)carbene ligand or via transmetalation reactions using (2-pyrrolyl)mercuric chloride

Article abstract of DOI:10.1021/om00019a009

The chloro(2-pyrrolyl)carbene complex Ru-(=C[Cl]-2-C₄H₃NH)Cl₂(CO)(PPh ₃)₂ (1) undergoes hydrolysis and rearrangement to give the σ-bound 2-pyrrolyl complex Ru(2-C₄H₃NH)Cl(CO)₂(PPh₃) ₂ (2). Compound 2, and the osmium analogue Os(2-C₄H₃NH)Cl-(CO)₂(PPh₃) ₂ (4), can be prepared by reaction of (2-pyrrolyl)mercuric chloride (3) with the low-oxidation-state compounds M(CO)₂(PPh₃)₃ (M = Ru, Os), respectively. Key steps in the synthesis of compound 3 involve protection of the pyrrolic nitrogen atom with a lithio-carboxylate function followed by selective lithiation and then mercuration in the ring 2-position.