Complexes of palladium and platinum with substituted benzo-[15-crown-5] ethers containing nitrogen-donor ligand atoms

Abstract

Some benzo-crown ethers substituted in the arene ring are described, e.g. the 15-X-substituted benzo-[15-crown-5] ethers (1; X = CN, CHNOH, or CH₃CNOH) and 15-CHNOH,16-CH₃-substituted benzo-[15-crown-5](8). The nitrile (1; X = CN)(L) reacts with PtCl₂ to give [PtCl₂L₂]. For comparison the ‘model’ compound [PtCl₂{NCC₆H₃(OMe)₂-3,4}₂] has also been prepared. Both react with hydrazine in air to give very stable, dark blue, triazabutadiene-platinum complexes [Pt{HNNC(R)NH}₂](2), where R = the benzo-crown radical (3)(free valence at 15-position) or 3,4-dimethoxyphenyl. The crown triazabutadiene–platinum complex gives a deep blue complex with sodium iodide. Both triazabutadiene–platinum complexes give green diacetates, and the crown diacetate interacts with sodium iodide or sodium thiocyanate in solution. The oximes (1; X = CHNOH or CH₃CNOH) are cyclopalladated by treatment with Na₂[PdCl₄]–Na[O₂CMe] exclusively in the 16-position to give chloro-bridged complexes (6). These complexes react with PPh₃ or PMe₂Ph to give mononuclear complexes (7). 3,4-Dimethoxybenzaldoxime is also cyclopalladated to give a product (4) which when treated with PPh₃ or PMe₂Ph gives mononuclear complexes (5). Complexes of the type [PdCl₂L₂], where L = 3,4-dimethoxybenzaldoxime or (1; X = CHNOH or CH₃CNOH) have also been prepared. Nuclear magnetic resonance, i.r., and mass spectral data are given.