Weak Exchange Interactions in Multispin Systems: EPR Studies of Metalloporphyrins Decorated with {Cr 7 Ni} Rings.

Both metalloporphyrins and heterometallic {Cr ₇ Ni} rings are of significant research interest due to their proposed roles in quantum information processing devices. In this study, we present a series of complexes in which [Cr ₇ NiF ₃ (Etglu)(O ₂ C ^t Bu) ₁₅ ] ( N -EtgluH ₅ = N -ethyl-d - glucamine) heterometallic rings are coordinated to metalloporphyrin linkers: the symmetric [M(TPyP)] for M = Cu ²⁺ , VO ²⁺ , and H ₂ TPyP = 5,10,15,20-tetra(4-pyridyl)porphyrin; and the asymmetric [{VO}(TrPPyP)] for H ₂ (TrPPyP) = 5,10,15-(triphenyl)-20-(4-pyridyl)porphyrin. The magnetic interactions present in these complexes are unraveled using the continuous wave (CW) electron paramagnetic resonance (EPR) technique. The nature of the coupling between the {Cr ₇ Ni} rings and the central metalloporphyrin is assessed by numerical simulations of CW EPR spectra and determined to be on the order of 0.01 cm ^-1 , larger than the dipolar ones and suitable for individual spin addressability in multiqubit architectures.