A luminescent Pt2Fe spin crossover complexElectronic supplementary information (ESI) available. CCDC 1510868-1510870. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6dt04360g

A heterotrinuclear [Pt 2 Fe] spin crossover (SCO) complex was developed and synthesized employing a ditopic bridging bpp-alkynyl ligand L and alkynyl coordinated Pt II terpy units: [Fe II ( L-Pt II ) 2 ] 2 (BF 4 ) 2 ( 1 ). We identified two different types of crystals of 1 which differ in their molecular packing and the number of co-crystallized solvent molecules: 1 H ( 1 ·3.5CH 2 Cl 2 in P 1&cmb.macr;) and 1 L ( 1 ·10CH 2 Cl 2 in C 2/ c ); while 1 L shows a reversible SCO with a transition temperature of 268 K, the analogous compound 1 H does not show any SCO and remains blocked in the HS state. The temperature-dependent magnetic properties of 1 H and 1 L were complementarily studied by Mössbauer spectroscopy. It has been shown that 1 L performs thermal spin crossover and that 1 L 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 II terpy units to the Fe II -moiety. A heterotrinuclear luminescent [Pt 2 Fe] spin crossover (SCO) complex was developed, synthesized, and investigated.