3-Diphenylphosphino-(1R)-(+)-camphor dimethylhydrazone complexes with platinum(II) and palladium(II)

Abstract

Treatment of the Z-exo-phosphine PPh₂C₁₀H₁₅NNMe₂1a with [PdCl₂(NCPh)₂] or Na₂[PdCl₄]·4H₂O gives the compound [[graphic omitted]Me₂)]2a with the PPh₂ group exo and the CNNMe₂ configuration Z, i.e. a six-membered ring chelate complex. The corresponding platinum complex 2d was made from 1a and [PtCl₂(cod)](cod = cycloocta-1,5-diene). Metathesis of complex 2a or 2d with LiBr, or 2a with NaI, gave the corresponding bromides or iodide. Treatment of 2d with AgNO₃ gave the mononitrato complex [[graphic omitted]Me₂)]2f. Treatment of [PtMe₂(cod)] with 1a gave [[graphic omitted]Me₂)]2g. The exo-phosphine 1a when treated with acetic acid or hot sodium ethoxide solution was partially converted into a mixture with the corresponding endo-phosphine 1b. Treatment of [PtCl₂(cod)] with the 1a–1b mixture gave a mixture of the Z-exo-/endo-chelate complexes [[graphic omitted]Me₂)]; similar treatment of [PdCl₂(NCPh)₂] or [PtMe₂(cod)] gave the corresponding exo-/endo-complexes. Treatment of 2d with hydrogen chloride gave a new (protonated) species which with ethanol gave the exo-/endo-mixture 2d–3a. The palladium complex 2a with hydrogen chloride followed by methanol gave 2a–3b. and another complex formulated as E-exo-[[graphic omitted]NMe₂)]5. Treatment of 2d with an excess of LiMe gave a new species formulated as an anion [[graphic omitted]Me₂)]^–4, which with methanol gave the exo-/endo-mixture 2g–3c. Proton, ¹³C-{¹H} and ³¹P-{¹H} NMR data are given and discussed in some detail particularly regarding the determination of the stereochemistry at C(3) on the camphor residue. Crystals of compound 2a are orthorhombic, space group P2₁2₁2₁ with a= 1165.1(2), b= 1272.5(2), c= 2106.1(5) pm and Z= 4; final R factor 0.0421 for 2812 observed reflections. The structure shows that the co-ordinated PPh₂ group is on the 3-exo position whilst the CNNMe₂ moiety is co-ordinated through the NMe₂ nitrogen giving a six-membered co-ordinated ring. The arrangement around CN is Z.