title: Cu(HCO2)2(pym) (pym = pyrimidine): low-dimensional magnetic behavior and long-range ordering in a quantum-spin lattice.
abstract: We synthesized and structurally and magnetically characterized the novel 3D coordination polymer Cu(HCO2)2(pym) (pym = pyrimidine). The compound crystallizes in the monoclinic space group C2/c with a = 14.4639(8) A, b = 7.7209(4) A, c = 8.5172(5) A, beta = 126.076(2) degrees, and V= 768.76(7) A3. In the structure buckled layers of Cu(HCO2)2 are interconnected by pym ligands to afford 1D Cu-pym-Cu chains. Bulk magnetic susceptibility measurements show a broad maximum at 25 K that is indicative of short-range magnetic ordering. Between 12 and 300 K a least-squares fit of the chi(T) data to a mean-field-corrected antiferromagnetic chain model yielded excellent agreement for g = 2.224(3), J/kB = -26.9(2) K, and zJ'/kB = -1.1(3) K. Below approximately 3 K a transition to long-range magnetic ordering is observed, as suggested by a sharp and sudden decrease in chi(T). This result is corroborated by muon spin relaxation measurements that show oscillations in the muon asymmetry below T(N) = 2.802(1) K and rapidly fluctuating moments above T(N).
authors.affiliation: Department of Chemistry and Biochemistry, Eastern Washington University, Cheney, Washington 99004, USA. jmanson@ewu.edu
authors.forename: J L
authors.initials: JL
authors.lastname: Manson
authors.forename: T
authors.initials: T
authors.lastname: Lancaster
authors.forename: L C
authors.initials: LC
authors.lastname: Chapon
authors.forename: S J
authors.initials: SJ
authors.lastname: Blundell
authors.forename: J A
authors.initials: JA
authors.lastname: Schlueter
authors.forename: M L
authors.initials: ML
authors.lastname: Brooks
authors.forename: F L
authors.initials: FL
authors.lastname: Pratt
authors.forename: C L
authors.initials: CL
authors.lastname: Nygren
authors.forename: J S
authors.initials: JS
authors.lastname: Qualls