title: Experimental and Theoretical Studies on the Magnetic Anisotropy in Lanthanide(III)-Centered Fe3 Ln Propellers.
abstract: Compounds [Fe3 Ln(tea)2 (dpm)6 ] (Fe3 Ln; Ln= Tb-Yb, H3 tea=triethanolamine, Hdpm=dipivaloylmethane) were synthesized as lanthanide(III)-centered variants of tetrairon(III) single-molecule magnets (Fe4 ) and isolated in crystalline form. Compounds with Ln=Tb-Tm are isomorphous and show crystallographic threefold symmetry. The coordination environment of the rare earth, given by two tea(3-) ligands, can be described as a bicapped distorted trigonal prism with D3 symmetry. Magnetic measurements showed the presence of weak ferromagnetic Fe⋅⋅⋅Ln interactions for derivatives with Tb, Dy, Ho, and Er, and of weak antiferromagnetic or negligible coupling in complexes with Tm and Yb. Alternating current susceptibility measurements showed simple paramagnetic behavior down to 1.8 K and for frequencies reaching 10000 Hz, despite the easy-axis magnetic anisotropy found in Fe3 Dy, Fe3 Er, and Fe3 Tm by single-crystal angle-resolved magnetometry. Relativistic quantum chemistry calculations were performed on Fe3 Ln (Ln=Tb-Tm): the ground J multiplet of Ln(3+) ion is split by the crystal field to give a ground singlet state for Tb and Tm, and a doublet for Dy, Ho, and Er with a large admixture of mJ states. Gyromagnetic factors result in no predominance of gz component along the threefold axis, with comparable gx and gy values in all compounds. It follows that the environment provided by the tea(3-) ligands, though uniaxial, is unsuitable to promote slow magnetic relaxation in Fe3 Ln species.
authors.affiliation: Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia and INSTM RU of Modena and Reggio Emilia via G. Campi 103, 41125 Modena (Italy).
authors.forename: Luca
authors.initials: L
authors.lastname: Rigamonti
authors.affiliation: Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia and INSTM RU of Modena and Reggio Emilia via G. Campi 103, 41125 Modena (Italy).|Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia via G. Campi 213/a, 41125 Modena (Italy).
authors.forename: Andrea
authors.initials: A
authors.lastname: Nava
authors.affiliation: Laboratory of Molecular Magnetism (LAMM), Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze and INSTM RU of Firenze via della Lastruccia 3-13, 50019 Sesto Fiorentino (Italy).|Present address: Photon Science Institute, EPSRC School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL (UK).
authors.forename: Marie-Emmanuelle
authors.initials: ME
authors.lastname: Boulon
authors.affiliation: Centro Universitario de la Defensa, Academia General Militar, Ctra. de Huesca s/n, 50090 Zaragoza (Spain).|Instituto de Ciencia de Materiales de Aragón CSIC, Universidad de Zaragoza, C/Pedro Cerbuna 12, 50009 Zaragoza (Spain).
authors.forename: Javier
authors.initials: J
authors.lastname: Luzon
authors.affiliation: Laboratory of Molecular Magnetism (LAMM), Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze and INSTM RU of Firenze via della Lastruccia 3-13, 50019 Sesto Fiorentino (Italy). roberta.sessoli@unifi.it.
authors.forename: Roberta
authors.initials: R
authors.lastname: Sessoli
authors.affiliation: Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia and INSTM RU of Modena and Reggio Emilia via G. Campi 103, 41125 Modena (Italy). acornia@unimore.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cornia
keywords: crystal structures; density functional calculations; iron; lanthanides; magnetic anisotropy