title: Linear Tricobalt Compounds with Di-(2-pyridyl)amide (dpa) Ligands: Studies of the Paramagnetic Compound Co(3)(dpa)(4)Cl(2) in Solution.
abstract: Solutions of Co(3)(dpa)(4)Cl(2), where dpa = di(2-pyridyl)amide ion, in CD(2)Cl(2) were studied by NMR in the temperature range 183-303 K. The spectra show only four (1)H and five (13)C resonance signals, consistent with the D(4) symmetry of the molecules found in the solid. The magnetic susceptibility in solution was determined by the Evans method from 193 to 308 K. These observations can be modeled as an S = 1/2 to S = 5/2 spin-transition process with DeltaH = 7.7(2) kJ mol(-1) and DeltaS = 20.8(8) J K(-1) mol(-1).
authors.affiliation: The Laboratory for Molecular Structure and Bonding, Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842-3012, and Department of Chemistry, University of Costa Rica, Ciudad Universitaria, Costa Rica.
authors.forename: F. Albert
authors.initials: FA
authors.lastname: Cotton
authors.forename: Carlos A.
authors.initials: CA
authors.lastname: Murillo
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wang