Palladium complexes of azines, α-diazines and α-2-pyridylazines containing (1R)-(+)-camphor or (1R)-(–)-fenchone groups
Abstract
Mixed monoazines of types H2CN–NC10H16[C10H16 is a (1R)-(+)-camphor residue (L1), or a (1R)-(–)-fenchone residue (L2)] or Me2CN–NC10H16[C10H16 is a (1R)-(+)-camphor residue (L3)], or α-diazines C10H16N–NCH–CHN–NC10H16[C10H16 is a (1R)-(+)-camphor residue (L4) or a (1R)-(–)-fenchone residue (L5)], or α-2-pyridyl azines C10H16N–NCHC5H4N [C10H16 is a (1R)-(+)-camphor residue (L6) or a (1R)-(–)-fenchone residue (L7)] reacted with Na2PdCl4 to give compounds of type [PdCl2Ln2] for L1, L2 or L3 as monodentate nitrogen-donor ligands and chelated mononuclear complexes of the type [PdCl2Ln] for L4, L5, L6 or L7. The complexes of the monodentate azines L1 and L2 exist in solution as mixtures of isomers differing in the ligating nitrogens. The compounds L1, L2 and L4–L7 also reacted with [Pd2Cl4(PR3)2] to give [PdCl2(PR3)Ln](n= 1, R3= Me2Ph or Me2(C6H4OMe-4); n= 2, R3= Me2Ph, Me2(C6H4OMe-4) or Ph3; n= 4 or 5, R3= Me2Ph; n= 6, R3= Bun3; n= 7, R3= Bun3 or Me2Ph), in which the ligands are monodentate, or [{PdCl2(PR3)}2Ln](Ln= L4–L7, R3= Me2Ph), in which the ligands are bidentate bridging. The phosphine complexes were characterised in solution but were isolated only for [PdCl2(PR3)Ln](Ln= L6, R3= Bun3; L7, R3= Bun3 or Me2Ph; L2, R3= Ph3). Compounds L4, L6 or L7 reacted with the η3-methylallylpalladium complex [{PdCl(η3-CH2CMeCH2)}2] and NH4PF6 to give [Pd(η3-CH2CMeCH2)Ln] PF6(Ln= L4, L6 or L7). The crystal structure of [PdCl2L6]·0.5CH2Cl2 was determined by X-ray diffraction analysis: the crystals are monoclinic, space group P21 with a= 9.5830(13), b= 13.9720(14) and c= 14.726(2)Å, β= 97.610(11)° and Z= 4. It shows two molecules of the complex in the asymmetric unit differing only in the torsion angles around the N–N bond.