Electronic structure and spin dynamics of two new AgII molecular systems as platforms for molecular spin qubits.

Two new complexes derived from the unusual AgII cation, with the formulas [Ag(cyclam)(BF4)2] (1) (cyclam = aza-crown 1,4,8,11-tetraazacyclotetradecane) and [Ag(tBu-bpy)2(S2O8)] (2) (tBu-bpy = 4,4'-bis(tert-butyl)-2,2'-bipyridine), have been synthesized and structurally, magnetically and spectroscopically characterized. The use of a combination of their magnetic response under an alternating field and ultralow Raman spectroscopy revealed that the two complexes exhibit slow relaxation of magnetization induced by spin-phonon interactions. CW-EPR and UV-Vis spectroscopy methods have been performed to investigate the electronic structure, supported by theoretical calculations. Pulsed-EPR experiments on diluted frozen solutions of the studied compounds allowed the investigation of their coherence properties, yielding Tm values of 4.8 and 2.7 µs at 20 K for 1 and 2, respectively. The observation of Rabi oscillations evidenced coherent spin manipulation by the microwave field, highlighting the potential of AgII-based coordination compounds as molecular candidates for emerging quantum technologies.