Synthesis, structures, and photoluminescence properties of novel lanthanide tetracyanoplatinates lacking Pt–Pt interactions

The synthesis of a series of lanthanide tetracyanoplatinates all incorporating 2,2′:6′,2″-terpyridine (terpy) have been carried out by reaction of Ln3+ nitrate salts with terpy and potassium tetracyanoplatinate. The incorporation of different Ln3+ cations results in the isolation of [Ln(DMF)2(C15H11N3)(H2O)2(NO3)]Pt(CN)4 (Ln=La–Nd, Sm–Yb) under otherwise identical reaction conditions. These compounds have been isolated as single crystals and X-ray diffraction has been used to investigate their structural features. All of the reported compounds are isostructural. Crystallographic data for the representative Eu3+ compound (EuPt) are (MoKα, λ=0.71073 Å): monoclinic, space group P21/c, a=10.1234(4) Å, b=18.7060(7) Å, c=17.1642(5) Å, β=97.249(3)°, V=3224.4(2), Z=4, R(F)=2.78% for 426 parameters with 7724 reflections with I>2σ(I). The structure consists of a zero-dimensional, ionic salt containing complex [Eu(DMF)2(C15H11N3)(H2O)2(NO3)]2+ cations and Pt(CN)42− anions. The complex cations contain the Eu3+ ions in a tri-capped trigonal prismatic coordination environment with one terdentate 2,2′:6′,2″-terpyridine molecule, one bidentate nitrate anion, two O-bound dimethylformamide molecules, and two coordinated water molecules. Photoluminescence data illustrate that EuPt displays intramolecular energy transfer from the coordinated terpy molecule to the Eu3+ cation. The uncoordinated tetracyanoplatinate anion also exhibits visible emission.

Graphical abstractThe synthesis of an isostructural series of lanthanide tetracyanoplatinates incorporating 2,2′:6′,2″-terpyridine are presented. Solid-state absorption and luminescence properties are discussed for the Eu3+ and La3+ compounds.Figure optionsDownload full-size imageDownload as PowerPoint slide