title: EPR spectroscopy of a family of Cr(III) 7M(II) (M = Cd, Zn, Mn, Ni) "wheels": studies of isostructural compounds with different spin ground states.
abstract: Spinning wheels: The presented highly resolved multifrequency continuous wave EPR spectra (e.g., see figure) of the heterooctametalic "wheels" Cr(7)M 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 present highly resolved multifrequency (X-, K-, Q- and W-band) continous wave EPR spectra of the heterooctametalic "wheels", [(CH(3))(2)NH(2)][Cr(III) (7)M(II)F(8)((CH(3))(3)CCOO)(16)], hereafter Cr(7)M, 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 subspaces 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 Cr(7)M family is possible and that the spin-Hamiltonian parameters of Cr(7)M do not have sharply defined values, but are rather distributed around a mean value.
authors.affiliation: Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark. piligkos@kiku.dk
authors.forename: Stergios
authors.initials: S
authors.lastname: Piligkos
authors.forename: Høgni
authors.initials: H
authors.lastname: Weihe
authors.forename: Eckhard
authors.initials: E
authors.lastname: Bill
authors.forename: Frank
authors.initials: F
authors.lastname: Neese
authors.forename: Hassane
authors.initials: H
authors.lastname: El Mkami
authors.forename: Graham M
authors.initials: GM
authors.lastname: Smith
authors.forename: David
authors.initials: D
authors.lastname: Collison
authors.forename: Gopalan
authors.initials: G
authors.lastname: Rajaraman
authors.forename: Grigore A
authors.initials: GA
authors.lastname: Timco
authors.forename: Richard E P
authors.initials: RE
authors.lastname: Winpenny
authors.forename: Eric J L
authors.initials: EJ
authors.lastname: McInnes
mesh_terms: D000465:Algorithms; D002104:Cadmium / Q000032:analysis / Q000737:chemistry; D002857:Chromium / Q000032:analysis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D008345:Manganese / Q000032:analysis / Q000737:chemistry; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D009532:Nickel / Q000032:analysis / Q000737:chemistry; D015032:Zinc / Q000032:analysis / Q000737:chemistry
chemical_list: D002104:Cadmium; D002857:Chromium; D008345:Manganese; D009532:Nickel; D015032:Zinc