Ligand Effects on the Spin Relaxation Dynamics and Coherent Manipulation of Organometallic La(II) Potential Qu d its

Abstract

We present pulsed electron paramagnetic resonance (EPR) studies on three La(II) complexes, [K(2.2.2-cryptand)][La(Cp′) 3] (1), [K(2.2.2-cryptand)][La(Cp″) 3] (2), and [K(2.2.2-cryptand)][La(Cp tt) 3] (3), which feature cyclopentadienyl derivatives as ligands [Cp′ = C 5H 4SiMe 3; Cp″ = C 5H 3(SiMe 3) 2; Cp tt = C 5H 3(CMe 3) 2] and display a C 3 symmetry. Long spin-lattice relaxation (T 1) and phase memory (T m) times are observed for all three compounds, but with significant variation in T 1 among 1-3, with 3 being the slowest relaxing due to higher s-character of the SOMO. The dephasing times can be extended by more than an order of magnitude via dynamical decoupling experiments using a Carr-Purcell-Meiboom-Gill (CPMG) sequence, reaching 161 μs (5 K) for 3. Coherent spin manipulation is performed by the observation of Rabi quantum oscillations up to 80 K in this nuclear spin-rich environment ( 1H, 13C, and 29Si). The high nuclear spin of 139La (I = 7/2), and the ability to coherently manipulate all eight hyperfine transitions, makes these molecules promising candidates for application as qudits (multilevel quantum systems featuring d quantum states; d >2) for performing quantum operations within a single molecule. Application of HYSCORE techniques allows us to quantify the electron spin density at ligand nuclei and interrogate the role of functional groups to the electron spin relaxation properties. Show more