title: Two acentric mononuclear molecular complexes with unusual magnetic and ferroelectric properties.
abstract: Two acentric, i.e., noncentrosymmetric, mononuclear complexes, Co(5-ATZ)(4)Cl(2), 1, and Cu(5-ATZ)(4)Cl(2), 2, where 5-ATZ is the monodentate 5-amino-1-H-tetrazole ligand, have been prepared and characterized. Both complexes crystallize in the tetragonal system with the P4nc space group, a member of the polar noncentrosymmetric 4mm class, and thus both 1 and 2 can exhibit ferroelectric and nonlinear optical properties. Magnetic studies indicate that 1 is a paramagnetic high-spin cobalt(II) complex with a rather extensive spin-orbit coupling, modeled as a zero-field splitting parameter, D, of ±91(3) cm(-1) and with very weak long-range antiferromagnetic exchange interactions. Direct current (dc) and ac magnetic studies indicate that 2 is a paramagnetic copper(II) complex that exhibits weak ferromagnetic exchange interactions below 15 K. Both 1 and 2 exhibit ferroelectric hysteresis loops at room temperature with remanent polarizations of 0.015 μC/cm(2) and coercive electric fields of 5.5 and 5.7 kV/cm, respectively.
authors.affiliation: Department of Chemistry, Nankai University, Tianjin 300071, China.
authors.forename: Fang-Hua
authors.initials: FH
authors.lastname: Zhao
authors.forename: Yun-Xia
authors.initials: YX
authors.lastname: Che
authors.forename: Ji-Min
authors.initials: JM
authors.lastname: Zheng
authors.forename: Fernande
authors.initials: F
authors.lastname: Grandjean
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Long