title: Synthesis, Structure, and Magnetism of Mono- and Binuclear Manganese(II) Compounds of Nitronyl Nitroxide Substituted Phosphine Oxides.
abstract: Complexes of manganese(II)-containing aminoxyl radical substituted phosphine oxide ligands are reported. The compounds [(o-nitronyl nitroxide-phenyl)diphenylphosphine oxide]bis(hexafluoroacetylacetonato)manganese(II), 3, and bis{[(p-nitronyl nitroxide-phenyl) diphenylphosphine oxide]bis(hexafluoroacetylacetonato)manganese(II)}, 4, prepared by addition of the free radical phosphine oxides to Mn(hfac)(2), were structurally characterized. Complex 3 is mononuclear, containing an O,O-chelating ortho-substituted radical phosphine oxide ligand, while in 4 the para-substituted ligands bridge two Mn(hfac)(2) units to yield a binuclear molecular rectangle. The magnetic behavior of both systems is dominated by a strong antiferromagnetic Mn(II)-aminoxyl interaction (J = -213 (3), -218 (4) cm(-)(1) with H = -JS(Mn).S(rad)) to give effective S = 2 ground state units. The S = 3 excited state is populated at high temperatures. At low temperatures a decrease in chi(M)T in both complexes is attributable primarily to inter- or intramolecular antiferromagnetic interactions rather than zero-field splitting (ZFS) of the S = 2 ground state. For the bimetallic compound, the magnetic data indicate that ligand-mediated interactions between the Mn(II) spin carriers are weak. The powder EPR spectra of both systems have been recorded and successfully simulated, giving a ZFS parameter D = 0.112 cm(-)(1). Crystals of 3 are triclinic, space group P&onemacr; with a = 10.6672(19) Å, b = 13.270(6) Å, c = 15.363(3) Å, alpha = 93.84(2) degrees, beta = 108.054(16) degrees, gamma = 105.69(3) degrees, and Z = 2. Crystals of 4 are monoclinic, space group P2(1)/a with a = 12.463(6) Å, b = 19.315(3) Å, c = 17.084(9) Å, alpha = 90 degrees, beta = 98.49(2) degrees, gamma = 90 degrees, and Z = 2.
authors.affiliation: Laboratoire des Sciences Moléculaires, Institut de Chimie de la Matière Condensée de Bordeaux, UPR CNRS No. 9048, F-33608 Pessac, France, Groupe Matériaux Moléculaires, UMR CNRS No. 6511, Université Rennes 1, F-35042 Rennes, France, and Centre de Physique Moléculaire Optique et Hertzienne, UMR CNRS Université Bordeaux 1, 351, cours de la Libération, F-33405 Talence, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Rancurel
authors.forename: Daniel B.
authors.initials: DB
authors.lastname: Leznoff
authors.forename: Jean-Pascal
authors.initials: JP
authors.lastname: Sutter
authors.forename: Stéphane
authors.initials: S
authors.lastname: Golhen
authors.forename: Lahcène
authors.initials: L
authors.lastname: Ouahab
authors.forename: Janis
authors.initials: J
authors.lastname: Kliava
authors.forename: Olivier
authors.initials: O
authors.lastname: Kahn