Luminescent Manganese(II) Iminophosphorane Derivatives.

The reaction between the iminophosphorane ligand N-phenyl-1,1,1-triphenylphosphanimine (NPh=PPh(3)) and anhydrous manganese(II) halides allowed the isolation of complexes with the general formula [MnX(2)(NPh=PPh(3))(2)] (X = Cl, Br, I). The compounds showed luminescence in the green region attributed to the (4)T(1)((4)G)→(6)A(1)((6)S) transition of the metal centre in the tetrahedral field, which was superimposed in the cases of X = Cl and X = Br on weak ligand-centred fluorescence. The emission and excitation spectra were compared with those of the free ligand and of the related zinc(II) bromo-complex. DFT calculations on the free ligand and on the manganese(II) bromo-complex helped to rationalise the experimental data. The protonation of NPh=PPh(3) led to the formation of the iminium cation [NHPh=PPh(3)](+), which was used as a building block for the synthesis of organic-inorganic hybrids with the general formula [NHPh=PPh(3)](2)[MnX(4)] (X = Cl, Br, I). The crystal structure of [NHPh=PPh(3)](2)[MnBr(4)] was determined by means of X-ray diffraction. Green photoluminescence associated with the metal-centred transition was also observed for the organic-inorganic hybrids, with higher quantum yields with respect to the neutral [MnX(2)(NPh=PPh(3))(2)] complexes. In the case of X = I, luminescence from the cation was superimposed on that from the tetraiodomanganate anion upon excitation of the compound with near-UV light.