Reactivity of cationic lanthanide(III) monoporphyrinates towards anionic cyanometallates - Preparation, crystal structure, and luminescence properties of cyanido-bridged di- and trinuclear d-f complexes

The metathesis reaction between two equivalents of [Ln-(tpp)(H ₂O)₃]Cl (Ln = Yb, Er; tpp^2- = tetraphenylporphyrinate dianion) and one equivalent of cyanometallate in dmf at room temperature under nitrogen for 24 hours gave the cyanido-bridged d-f trinuclear complexes [{Ln(tpp)(dmf)_n}₂{(μ-NC) ₂M(CN)₂}] (Ln = Yb, n = 2, M = Ni, 1; Ln = Er, n = 3, M = Ni, 2; Ln = Yb, n = 2, M = Pt, 3; Ln = Er, n = 3, M = Pt, 4), a trinuclear complex [{Er(tpp)(dmf)₂}{(μ-NC)₂Fe(CN) ₄}{Er-(Htpp)(dmf)₂}] (5), and a dinuclear complex [{Er(tpp)(dmf)-(H₂O)}(μ-NC)Ag(CN)] (6) when the cyanometallate used was the dianion [M(CN)₄]^2- (M = Ni, Pt), the trianion [Fe-(CN)₆]^3-, and monoanion [Ag(CN)₂] ^-, respectively. The solid-state structures of these complexes were ascertained by X-ray crystallography. Photoluminescence studies of complexes 1-4 showed that these complexes displayed photophysical properties characteristic of normal metal-porphyrinato complexes. Their absorption bands and emission peaks in the visible region are typical of the intraligand π→π* transitions of the porphyrinato ligand. Furthermore, these complexes also exhibited emission characteristic of the lanthanide(III) ion in the near-infrared (NIR) region, which was quenched by the cyanometallates.