title: Unusual Fe9 and Fe18 structural types from the use of 2,6-pyridinedimethanol in Fe(III) cluster chemistry.
abstract: The syntheses, crystal structures and magnetochemical characterization are reported for two new Fe(III) complexes [Fe(18)O(6)(OH)(8)(pdm)(10)(pdmH)(4)(H(2)O)(4)](ClO(4))(10) (3) and [Fe(9)O(4)(OH)(2)(O(2)CMe)(10)(pdm)(pdmH)(4)](NO(3)) (4). They were synthesized from the use of the potentially O,N,O tridentate chelate, 2,6-pyridinedimethanol (pdmH(2)), in the presence or absence of carboxylate groups. Octadecanuclear complex 3 was obtained during reactivity studies on previously-reported [Fe(8)O(3)(OEt)(pdm)(4)(pdmH)(4)(EtOH)(2)](ClO(4))(5) (2), the latter undergoing hydrolysis to 3 on recrystallization from undried MeCN. The reaction of pdmH(2) with preformed [Fe(3)O(O(2)CMe)(6)(py)(3)](NO(3)) in CH(2)Cl(2) gave enneanuclear complex 4. Both complexes 3 and 4 are unprecedented structural types. The core of 3 comprises a central [Fe(4)O(6)] defective-dicubane attached on either side to a [Fe(7)O(11)] unit, which can be described as two [Fe(4)(μ(4)-O)] tetrahedra fused at a common Fe atom. The core of 4 can be considered as four vertex-fused triangular [Fe(3)(μ(3)-O)] units. Variable-temperature (T) and -field (H) solid-state dc and ac magnetization (M) studies were carried out on complexes 3 and 4 in the 1.8-300 K range. Analysis of the obtained data revealed that complexes 3 and 4 possess an S = 4 and S = 5/2 ground state spin, respectively.
authors.affiliation: Department of Chemistry, University of Florida, Gainesville, FL 32611, USA.
authors.forename: Taketo
authors.initials: T
authors.lastname: Taguchi
authors.forename: Michael S
authors.initials: MS
authors.lastname: Thompson
authors.forename: Khalil A
authors.initials: KA
authors.lastname: Abboud
authors.forename: George
authors.initials: G
authors.lastname: Christou
mesh_terms: D018360:Crystallography, X-Ray; D005290:Ferric Compounds / Q000737:chemistry*; D008280:Magnetics; D000432:Methanol / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D009942:Organometallic Compounds; D011725:Pyridines; C023666:pyridine; D000432:Methanol