One-Pot Synthesis of New Organometallic Compounds with Platinum-Carbon Bond

Organometallic compounds of platinum containing ortho metalated para-nitro-benzamidate or 1-naphthalene-methylamine have been prepared by one-pot synthesis. The para-nitro-benzamidate [Pt{K2C,N-pNO2-C6H4C(O)NH}(R,R-DACH)] (compound 2) was obtained starting from [PtCl2(R,R-DACH)] and para-nitro-benzonitrile, which, in the reaction conditions, hydrolyzes to the corresponding amide and forms the dinuclear intermediate [Pt2{µ-N,O-pNO2-C6H4C(O)NH}2(R,R-DACH)2]SO4 (compound 1·SO4) with HH or HT arrangement of the two bridging amidato ligands. Compound 1·SO4, kept at 90 °C for few hours, transforms into 2. The ortho-metalated PtII derivative with 1-naphthalene-methylamine [PtCl{K2C,N-C10H6CH2NH2}(DMSO)] (3) was obtained by direct reaction of [PtCl2(DMSO)2] with the amine. Unlike compound 2 that has no labile ligands, compound 3 has Cl and DMSO ligands that can be released, allowing the formation of cross-links with DNA. Oxidation of 3 to the PtIV counterpart was performed with PhICl2 (compound 4). Unexpectedly, although six-coordinate complexes of PtIV are considered to be inert, 4 underwent spontaneous isomerization from the mer to the fac isomer. All compounds have been fully characterized by multinuclear NMR spectroscopy, which has enabled complete assignment of all proton resonances. In the case of compound 2, a single-crystal X-ray investigation was also performed, showing, with the only exception of the puckered cyclohexane ring, a complete planarity of the complex frame, which could favor an intercalative interaction with DNA.