Heteroleptic platinum(II) isocyanide complexes: convenient synthetic access, polymorphs, and vapoluminescence.

A convenient synthetic scheme was developed to access a series of square-planar Pt(II) complexes of the form (TBA)[Pt(CN)3(CNR)] (TBA = tetra-n-butyl ammonium cation, R = CH3, c-C6H11, p-(C2H5)-C6H4). These heteroleptic complexes were characterized by combustion analyses, single-crystal X-ray structure determinations, HRFAB-MS, (1)H NMR, ATR-IR, solution UV-Vis, and solid-state emission spectroscopies. Surprisingly, each of these complexes exhibit low energy room temperature solid-state luminescence in the absence of intermolecular Pt-Pt interactions. Additionally, the polymorphic behavior of (TBA)[Pt(CN)3(CN-c-C6H11)] was elucidated through a combination of single-crystal X-ray structure determinations, X-ray powder diffraction, and mass uptake experiments. Vapoluminescence and polymorphic transformations of (TBA)[Pt(CN)3(CN-c-C6H11)] were concomitant with water vapor absorption. A new double-salt complex [Pt(terpy)Cl] [Pt(CN)3(CNCH3)] (terpy = 2,2',6',2''-terpyridine) was also synthesized and characterized by combustion analysis, ATR-IR, HRFAB-MS, and solid-state UV-Vis and emission spectroscopies. The vapoluminescent properties of this salt in response to water were examined by mass uptake experiments, ATR-IR, and solid-state emission spectroscopy. A principal component analysis (PCA) of the solid-state emission changes induced by water vapor confirmed the presence of an intermediate emissive species.