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

Both metalloporphyrins and heterometallic {CrNi} 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 [CrNiF(Etglu)(OCBu)] (-EtgluH = -ethyl-dglucamine) heterometallic rings are coordinated to metalloporphyrin linkers: the symmetric [M(TPyP)] for M = Cu, VO, and HTPyP = 5,10,15,20-tetra(4-pyridyl)porphyrin; and the asymmetric [{VO}(TrPPyP)] for H(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 {CrNi} 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, larger than the dipolar ones and suitable for individual spin addressability in multiqubit architectures.