title: Ultralarge 3d/4f Coordination Wheels: From Carboxylate/Amino Alcohol-Supported {Fe4Ln2} to {Fe18Ln6} Rings.
abstract: A family of wheel-shaped charge-neutral heterometallic {FeIII4LnIII2}- and {FeIII18MIII6}-type coordination clusters demonstrates the intricate interplay of solvent effects and structure-directing roles of semiflexible bridging ligands. The {Fe4Ln2}-type compounds [Fe4Ln2(O2CCMe3)6(N3)4(Htea)4]·2(EtOH), Ln = Dy (1a), Er (1b), Ho (1c); [Fe4Tb2(O2CCMe3)6(N3)4(Htea)4] (1d); [Fe4Ln2(O2CCMe3)6(N3)4(Htea)4]·2(CH2Cl2), Ln = Dy (2a), Er (2b); [Fe4Ln2(O2CCMe3)4(N3)6(Htea)4]·2(EtOH)·2(CH2Cl2), Ln = Dy (3a), Er (3b) and the {Fe18M6}-type compounds [Fe18M6(O2CCHMe2)12(Htea)18(tea)6(N3)6]·n(solvent), M = Dy (4, 4a), Gd (5), Tb (6), Ho (7), Sm (8), Eu (9), and Y (10) form in ca. 20-40% yields in direct reaction of trinuclear FeIIIpivalate or isobutyrate clusters, lanthanide/yttrium nitrates, and bridging triethanolamine (H3tea) and azide ligands in different solvents: EtOH for the smaller {Fe4Ln2} wheels and MeOH/MeCN or MeOH/EtOH for the larger {Fe18M6} wheels. Single-crystal X-ray diffraction analyses revealed that 1-3 consist of planar centrosymmetric hexanuclear clusters built from FeIIIand LnIIIions linked by an array of bridging carboxylate, azide, and aminopolyalcoholato-based ligands into a cyclic structure with a cavity, and with distinct sets of crystal solvents (2 EtOH per formula unit in 1a-c, 2 CH2Cl2in 2, and 2 EtOH and 2 CH2Cl2in 3). In 4-10, the largest 3d/4f wheels currently known, nearly linear Fe3fragments are joined via mononuclear Ln/Y units by a set of isobutyrates and amino alcohol ligands into virtually planar rings. The magnetic properties of 1-10 reveal slow magnetization relaxation for {Fe4Tb2} (1d) and slow relaxation for {Fe4Ho2} (1c), {Fe18Dy6} (4), and {Fe18Tb6} (6).
authors.affiliation: Institute of Applied Physics, Academy of Sciences of Moldova , 2028 Chisinau, Moldova.|Institute of Inorganic Chemistry, RWTH Aachen University , 52074 Aachen, Germany.
authors.forename: Olga
authors.initials: O
authors.lastname: Botezat
authors.affiliation: Institute of Inorganic Chemistry, RWTH Aachen University , 52074 Aachen, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: van Leusen
authors.affiliation: Institute of Applied Physics, Academy of Sciences of Moldova , 2028 Chisinau, Moldova.
authors.forename: Victor Ch
authors.initials: VC
authors.lastname: Kravtsov
authors.affiliation: Institute of Inorganic Chemistry, RWTH Aachen University , 52074 Aachen, Germany.
authors.forename: Paul
authors.identifier: http://orcid.org/0000-0001-7831-3953
authors.initials: P
authors.lastname: Kögerler
authors.affiliation: Institute of Applied Physics, Academy of Sciences of Moldova , 2028 Chisinau, Moldova.
authors.forename: Svetlana G
authors.identifier: http://orcid.org/0000-0002-2121-2091
authors.initials: SG
authors.lastname: Baca