ISOTHIOCYANATE LIGAND DERIVATIVES OF PLATINUM(II) TERPYRIDINES

The novel compounds [Pt(trpy)(NCS)]SbF6 (1) and [Pt{4'-(Ph)trpy}(NCS)]SbF6 (2) where trpy = 2,2':6',2''-terpyridine, have been synthesised and characterised by means of elemental analysis, infrared and 1H NMR spectroscopy, and mass spectroscopy. Compounds 1 and 2 were also prepared with the labelled S13C15N ¯ ion as co-ligand; their 13C and 15N NMR spectra recorded at room temperature in CD3CN show that the ambidentate ion is coordinated to the Pt atom mainly ( ~ 95%) through the N atom, but that a small amount of the S-bound isomer also co-exists in an acetonitrile solution. The synthesis of 1 is preceded by the isolation of yellow 1·CH3CN─Y (Y = yellow) for which the crystal structure has been determined by single crystal X-ray diffraction; this shows that the SCN ¯ ion is linearly bound to the Pt atom through the N atom in the solid state, and that the cation is planar. The solvate rapidly loses acetonitrile to form maroon 1─M (M = maroon). The maroon compound exhibits 3MMLCT (metal-metal-to-ligand charge transfer) emission in the solid state as evidenced by a red-shift in the emission maximum from 653 nm at 473 K to 770 nm at 80 K. However, there are anomalou