Influence of Electronic Spin and Spin−Orbit Coupling on Decoherence in Transition Metal Complexes

Enabling the rational synthesis of molecular candidates for quantum information processing requires design principles that minimize electron spin decoherence. Two series of paramagnetic coordination complexes, [M(C2O4)3]3- (M = Ru, Cr, Fe) and [M(CN)6]3- (M = Fe, Ru, Os), were prepared and subsequently interrogated by pulsed electron paramagnetic resonance spectroscopy to assess quantitatively the influence of the magnitude of spin (S = 1/2, 3/2, 5/2) and spin–orbit coupling (ζ = 464, 880, 3100 cm–1) on decoherence. The results illustrate that the design of qubit candidates can be achieved with a wide range of paramagnetic ions and spin states while preserving a long-lived coherence.