Intermolecular stacking of a tetranuclear cyclic Pt(II) complex: NMR characterization and X-ray crystal structure of cis–trans–cis–trans tetra[μ-2,6-diethynyl-4-nitroaniline-bis(tri(p-tolyl)phosphine)platinum(II)]

The synthesis and characterization of a tetranuclear Pt complex, cis–trans–cis–trans tetra[μ-2,6-diethynyl-4-nitroaniline-bis(tri(p-tolyl)phosphine) platinum(II)], namely [L2Pt-DENA]4 with L = tri-p-tolylphosphine, is reported. The complex was obtained by the dehydrohalogenative condensation of 2,6-diethynyl-4-nitroaniline (DENA) with cis-[dichlorobis(tri(p-tolyl)phosphine)platinum(II)]. The single crystal structure determination of [L2Pt-DENA]4 indicated the formation of a neutral molecular cycle with four alternating platinum units in cis and trans configurations, all bridged with DENA spacers with the presence of solvent (toluene) crystallization molecules. A twisted tetranuclear cyclic feature was identified. The formation of intermolecular stacks of the tetranuclear complex in solution was assessed by means of nuclear Overhauser enhancement spectroscopy (NOESY) and rotating frame Overhauser effect spectroscopy (ROESY) characterizations.

Graphical abstractA cyclic complex containing four Pt(II) centers bridging four 2,6-diethynyl-4-nitroaniline spacers was obtained. X-ray crystal structure showed the formation of alternate of cis and trans Pt centers in a twisted cyclic structure. NOESY and ROESY studies gave support to the presence of intermolecular stacking interactions among adjacent cycles.Figure optionsDownload full-size imageDownload as PowerPoint slide