title: Mn7 species with an S = 29/2 ground state: high-frequency EPR studies of a species at the classical/quantum spin interface.
abstract: A high spin (S) compound has been synthesized whose properties straddle the interface between the classical and quantum mechanical spin descriptions. The cluster [Mn(7)O(4)(pdpm)(6)(N(3))(4)](ClO(4))(2) (Mn(7)) has an unprecedented core structure comprising an octahedral [Mn(III)(6)(μ(4)-O)(μ(3)-O)(3)(μ(3)-N(3))(4)](6+) unit with one of its faces capped by a Mn(II) ion. Magnetization and susceptibility studies indicate an S = (29/2) ground state, the maximum possible. Variable-temperature, high-frequency electron paramagnetic resonance (HF-EPR) spectra on powder and single-crystal samples of Mn(7) exhibit sharp spectral features characteristic of a quantum spin that are well resolved in a certain temperature range but which transform to a continuum of peaks characteristic of a classical spin in another; these features have been well reproduced by computer simulations. A fast Fourier transform analysis of the sharp spectral features and the low temperature EPR spectra suggests that more than one spin state are involved.
authors: Department of Chemistry and Biochemistry, and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32306, United States.
authors: Zhenxing
authors: Z
authors: Wang
authors: Johan
authors: J
authors: van Tol
authors: Taketo
authors: T
authors: Taguchi
authors: Matthew R
authors: MR
authors: Daniels
authors: George
authors: G
authors: Christou
authors: Naresh S
authors: NS
authors: Dalal