Hydrazine complexes of ruthenium with cyclopentadienyl and indenyl ligands: Preparation and reactivity

•Synthesis of half-sandwich hydrazine complexes of ruthenium.•Selective oxidation of coordinated RNHNH2 to diazene.•Insertion of aryldiazonium cations into the Ru–H bond yielding aryldiazene derivatives.

Hydrazine complexes [Ru(η5-C5H5)(RNHNH2)(PPh3){P(OMe)3}]BPh4 (1–3) and [Ru(η5-C9H7)(RNHNH2) (PPh3){P(OEt)3}]BPh4 (4–6) (R = H, Me, Ph) were prepared by allowing chloro-compounds RuCl(η5-C5H5) (PPh3)[P(OMe)3] and RuCl(η5-C9H7) (PPh3)[P(OEt)3] to react with an excess of hydrazine in refluxing ethanol. Treatment of complexes 1–6 with Pb(OAc)4 at −40 °C yielded diazene derivatives [Ru(η5-C5H5)(RNNH) (PPh3){P(OMe)3}]BPh4 (7, 8) and [Ru(η5-C9H7) (RNNH)(PPh3){P(OEt)3}]BPh4 (10, 11) (R = Me, Ph). Aryldiazene complexes [Ru(η5-C5H5)(RNNH)(PPh3){P(OMe)3}]BPh4 (8, 9) (R = Ph, p-tolyl) were also prepared by allowing hydride RuH(η5-C5H5)(PPh3)[P(OMe)3] to react with aryldiazonium salts [RN2]+BF4– in CH2Cl2. The complexes were characterised by spectroscopy (IR, 1H, 31P NMR) and X-ray crystal structure determination of [Ru(η5-C9H7)(PhNHNH2)(PPh3){P(OEt)3}]BPh4 (6).

Graphical abstractThe preparation of half-sandwich hydrazine complexes of ruthenium stabilised by cyclopentadienyl and indenyl ligands is described. Related diazene derivatives were obtained by both selective oxidation of coordinated hydrazine and insertion of aryldiazonium cations into the Ru–H bond of the hydride precursor.Figure optionsDownload full-size imageDownload as PowerPoint slide