Tri(allyl)- and tri(methylallyl)arsine complexes of palladium(ii) and platinum(ii): synthesis, spectroscopy, photochemistry and structures

Abstract

Tri(allyl)- and tri(methylallyl)arsine complexes of palladium(II) and platinum(II) with the formulae [MX2L2] (M=Pd, Pt and X=Cl, Br, I): [Pd2Cl2(μ-Cl)2L2], [PdCl(S2CNEt2)L] and [Pd2Cl2(μ-dmpz)2L2] [L=As(CH2CHCH2)3 (L′), As(CH2CMeCH2)3 (L″), dmpz=3,5-dimethylpyrazolate] have been prepared. All the complexes have been characterized by elemental analyses and by IR and NMR (1H, 13C, 195Pt) spectroscopy. The stereochemistry of the complexes has been deduced from the spectroscopic data. The molecular structures of complexes [MX2{As(CH2CHCH2)3}2] (M=Pd, X=Cl or Br), [MX2{As(CH2CMeCH2)3}2] (M=Pd, X=Cl or Br; M=Pt, X=Cl) and [Pd2Cl2(μ-Cl)2{As(CH2CMeCH2)3}2] have been established by single crystal X-ray diffraction analyses. The mononuclear complexes exclusively adopt the trans configuration with the exception of [PdCl2L″2], which could be isolated as cis and trans isomers. In the binuclear derivative the arsine ligands are attached to an envelope-shaped Pd–(μ-Cl)2–Pd rectangle with a trans (anti) orientation towards each other. The mononuclear complexes are slightly photoreactive upon irradiation in their long-wavelength absorption band.