title: Enhancing the Magnetic Anisotropy of Linear Cr(II) Chain Compounds Using Heavy Metal Substitutions.
abstract: Magnetic properties of the series of three linear, trimetallic chain compounds Cr2Cr(dpa)4Cl2, 1, Mo2Cr(dpa)4Cl2, 2, and W2Cr(dpa)4Cl2, 3 (dpa = 2,2'-dipyridylamido), have been studied using variable-temperature dc and ac magnetometry and high-frequency EPR spectroscopy. All three compounds possess an S = 2 electronic ground state arising from the terminal Cr(2+) ion, which exhibits slow magnetic relaxation under an applied magnetic field, as evidenced by ac magnetic susceptibility and magnetization measurements. The slow relaxation stems from the existence of an easy-axis magnetic anisotropy, which is bolstered by the axial symmetry of the compounds and has been quantified through rigorous high-frequency EPR measurements. The magnitude of D in these compounds increases when heavier ions are substituted into the trimetallic chain; thus D = -1.640, -2.187, and -3.617 cm(-1) for Cr2Cr(dpa)4Cl2, Mo2Cr(dpa)4Cl2, and W2Cr(dpa)4Cl2, respectively. Additionally, the D value measured for W2Cr(dpa)4Cl2 is the largest yet reported for a high-spin Cr(2+) system. While earlier studies have demonstrated that ligands containing heavy atoms can enhance magnetic anisotropy, this is the first report of this phenomenon using heavy metal atoms as "ligands".
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States.
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Christian
authors.affiliation: Department of Chemistry, University of Wisconsin - Madison , 1101 University Avenue Madison, Wisconsin 53706, United States.
authors.forename: David W
authors.initials: DW
authors.lastname: Brogden
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States.
authors.forename: Jasleen K
authors.initials: JK
authors.lastname: Bindra
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States.
authors.forename: Jared S
authors.initials: JS
authors.lastname: Kinyon
authors.affiliation: National High Magnetic Field Laboratory, Florida State University , 1800 East Paul Dirac Drive, Tallahassee, Florida 32306, United States.
authors.forename: Johan
authors.initials: J
authors.lastname: van Tol
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States.
authors.forename: Jingfang
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of Wisconsin - Madison , 1101 University Avenue Madison, Wisconsin 53706, United States.
authors.forename: John F
authors.initials: JF
authors.lastname: Berry
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States.
authors.forename: Naresh S
authors.initials: NS
authors.lastname: Dalal