EPR Spectroscopy of a Family of (Cr7MnII)-Mn-III (M = Cd, Zn, Mn, Ni) "Wheels": Studies of Isostructural Compounds with Different Spin Ground States

We present highly resolved multifrequency (X-, K-, Q- and W-band) continous wave EPR spectra of the heterooctametalic "wheels", [(CH3)(2)NH2][(Cr7MF8)-M-III-F-II-((CH3)(3)CCOO)(16)], hereafter Cr7M, where M=Cd, Zn, Mn, and Ni. These experimental spectra provide rare examples of high nuclearity polymetallic systems where detailed information on the spin-Hamiltonian parameters of the ground and excited spin states is observed. We interpret the EPR spectra by use of restricted size effective sub-spaces obtained by the rigorous solution of spin-Hamiltonians of dimension up to 10(5) by use of the Davidson algorithm. We show that transferability of spin-Hamiltonian parameters across complexes of the Cr7M family is possible and that the spin-Hamiltonian parameters of Cr7M do not have sharply defined values, but are rather distributed around a mean value.