A luminescent Pt 2 Fe spin crossover complex

• Published in: Dalton transactions : an international journal of inorganic chemistry 2017-02, Vol.46 (7), p.2289-2302
• Main Authors: Schäfer, Bernhard, Bauer, Thomas, Faus, Isabelle, Wolny, Juliusz A, Dahms, Fabian, Fuhr, Olaf, Lebedkin, Sergei, Wille, Hans-Christian, Schlage, Kai, Chevalier, Katharina, Rupp, Fabian, Diller, Rolf, Schünemann, Volker, Kappes, Manfred M, Ruben, Mario
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c6dt04360g

A heterotrinuclear [Pt Fe] spin crossover (SCO) complex was developed and synthesized employing a ditopic bridging bpp-alkynyl ligand L and alkynyl coordinated Pt terpy units: [Fe (L-Pt ) ] (BF ) (1). We identified two different types of crystals of 1 which differ in their molecular packing and the number of co-crystallized solvent molecules: 1H (1·3.5CH Cl in P1[combining macron]) and 1L (1·10CH Cl in C2/c); while 1L shows a reversible SCO with a transition temperature of 268 K, the analogous compound 1H does not show any SCO and remains blocked in the HS state. The temperature-dependent magnetic properties of 1H and 1L were complementarily studied by Mössbauer spectroscopy. It has been shown that 1L performs thermal spin crossover and that 1L can be excited to a LIESST state. The vibrational properties of 1 were investigated by experimental nuclear resonance vibrational spectroscopy. The experimentally determined partial density of vibrational states (pDOS) was compared to a DFT-based simulation of the pDOS. The vibrational modes of the different components were assigned and visualized. In addition, the photophysical properties of 1 and L-Pt were investigated in the solid state and in solution. The ultrafast transient absorption spectroscopy of 1 in solution was carried out to study the PL quenching channel via energy transfer from photoexcited Pt terpy units to the Fe -moiety.