Synthesis and structures of copper and gold complexes of the P,N ligands RNC(But)C(H)RPPh2 (R = SiMe3, H)

The reaction of the chelating P,N ligand RNC(But)CH(R)PPh2 (R = SiMe3) (1) with CuCl and CuCl2 (probably by way of reduction to Cu(I) by the phosphine ligand) or Cu(NCCH3)4ClO4 yielded the dimeric 1:1 complex [Cu{PPh2CH(R)C(But)NR}Cl]2 (2) or the monomeric 2:1 complex [Cu{PPh2CH(R)C(But)NR}2]ClO4 (3), respectively. The presence of trace amounts of water during the reaction resulted in the successive cleavage of the two trimethylsilyl groups of the ligand and the formation of the monomeric chelate complexes [Cu{PPh2CH(R)C(But)NH}2]ClO4 (4) and [Cu{PPh2CH2C(But)NH}2]ClO4 (5). Oxidation of 5 by atmospheric oxygen led to small quantities of the blue Cu(II) complex [Cu{(O)PPh2CH2C(But)NH}2](ClO4)2 (6). The dimeric gold complexes [Au{PPh2CH2C(But)NH}]2X2 (X = BF4, ClO4) (7) were similarly obtained from the previously described Au{PPh2CH(R)C(But)NR}Cl by replacing the covalently bound chlorine with the weakly coordinating anions ClO4-andBF4- in the presence of small quantities of water. The solution and solid state structures (except 5) of all complexes were determined by NMR spectroscopy and X-ray crystallography.

Graphical abstractCu(I,II) and Au(I) complexes of the potentially chelating P,N ligands RNC(But)CH(R)PPh2 (R = SiMe3, H) have been synthesised and studied in the solid state and solution. The R group at the N atom was found to have a large influence on the chelating behaviour of the ligand.Figure optionsDownload full-size imageDownload as PowerPoint slide