Reactions of complexes of ruthenium and osmium halides with ammonia, amines, and hydrazine

Abstract

Ammonia and primary amines (am) react with [MX₃(PR₃)₃](M = Ru or Os, X = Cl or Br, and PR₃= tertiary phosphine) in ethanol at 20° to form M(II) complexes, mer-[MX₂am(PR₃)₃], and acetaldehyde. Secondary and tertiary amines with [MX₃(PMe₂Ph)₃] also cause reduction, but the product is an alcohol complex [MX₂(C₂H₅OH)(PMe₂Ph)₃]. The reduction may occur through a hydride complex intermediate because some hydrogen is produced in all the above reactions. The alcohol complexes are probably formed for steric reasons because the least sterically hindered secondary amine, piperidine, forms a piperidine complex.

When the alcohol contains a small amount of water di-n-alkylamines (C_nH_{2n+ 1})₂NH are dealkylated to form the corresponding primary amine complexes [MX₂ am (PR₃)₃](cf. similar decarbonylation of alcohol and aldehydes). The cleaved alkyl group generally appears as C_n–1H_2n and all the lower n-alkanes down to methane, but from dimethylamine higher hydrocarbons are obtained and from diethylamine a little propane.

Hydrazine in limited amounts forms mononuclear complexes [MCl₂(N₂H₄)(PMe₂Ph)₃] or more commonly hydrazine-bridged complexes [M₂X₄(N₂H₄)₂(PR₃)₄]. Nitrogen, hydrogen, and hydrazine hydrochloride are also produced. Under more vigorous reaction conditions [Ru(NH₃)₅N₂]²⁺ is formed.