Highly Emissive Cycloplatinated(II) Complexes Obtained by the Chloride Abstraction from the Complex [Pt(ppy)(PPh3)(Cl)]:Employing Various Silver Salts

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In the present investigation, the precursor complex [Pt(ppy)(PPh3)(Cl)], 3, ppy = 2-phenylpyridinyl, undergoes the chloride abstraction reaction using various AgX (X = PF6, BF4, NO3 and CH3COO) salts. Depending on the nature of anions in AgX salts (coordinating or noncoordinating), the products can be neutral or ionic. In the cases of NO3 and CH3COO, they can be coordinated to the Pt center so that the neutral complexes [Pt(ppy)(PPh3)(NO3)], 4a, and [Pt(ppy)(PPh3)(CH3COO)], 4b, are formed. In contrast, the ionic complexes [{Pt(ppy)(PPh3)(CH3CN)}PF6], 5a, and [{Pt(ppy)(PPh3)(CH3CN)}BF4], 5b, can be generated when the AgPF6 ([{Ag(CH3CN)4}PF6]) or AgBF4 ([{Ag(CH3CN)4}BF4]) salts are used in which the PF6 and BF4 stand as counteranions. In these two complexes, CH3CN fills the empty ligand position which can be present as solvent or ligand in the initial silver salts. The structures of the new complexes were accurately deduced from the multinuclear (1H, 31P{1H}, 195Pt{1H}) NMR spectroscopy and further authenticated by X-ray crystallography. Interestingly, the complexes are green emitters under various states and temperature conditions for which nonchelating L/X (PPh3/NO3 or PPh3/CH3COO) and L/L (PPh3/CH3CN) ancillary ligands exist in the structure of cycloplatinated(II) complexes. The photophysical properties of these new complexes, supported by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations, were investigated by photoluminescence and UV–vis spectroscopies.