Hidden Heterometallic Interaction Emerging from Resonant Inelastic X‑ray Scattering in Luminescent Tb–Pt Molecules

Theoretical
calculations are typically utilized for examining intermetallic
interactions. However, to validate the theory, experimental confirmation
of the existence of these interactions is necessary. We synthesized
new heterometallic Ln–Pt complexes, NEt4{[Pt­(PhSAc)4]­Ln­[(PhSAc)4Pt]}·2DMF (Ln: lanthanoid = Gd
(1), Tb (2), Dy (3), PhSAc
= benzothioacetate, NEt4 = tetraethylammonium), in which
both diamagnetic Pt­(II) ions interact with the central Ln­(III) ion.
Typically, these interactions are not detected because the distance
between Ln and Pt atoms (∼3.6 Å) is much larger than the
covalent radius (∼3.3 Å) and ionic radius (∼3.10
Å). Pt–LIII resonant inelastic
X-ray scattering (RIXS) analysis was conducted to experimentally confirm
the unique influence of the hidden Ln–Pt interaction on the
luminescence of the Tb–Pt molecule, where the interaction induced
emission properties in the Tb and Pt ions, with high quantum yield
(59%). Quantum theory of atoms in molecules (QTAIM) analysis was also
used to confirm the experimental results. RIXS analysis allowed the
identification of several distinctive characteristics of the coordination
environment, including the existence of heterometallic interactions,
that affected the observed luminescence.