title: Reactivity of 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole, structures and magnetic properties of polynuclear and polymeric Mn(II), Cu(II) and Cd(II) complexes.
abstract: Five new complexes were obtained from solution or hydrothermal reactions of M(OAc)(2) (M = Mn, Cu and Cd) or CuCl(2) with 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (abpt) and NaN(3) or 1,3,5-benzenetricarboxylic acid (btcH(3)) in different molar ratios. Structural analysis reveals that Cd(abpt) units in [Cd(abpt)(mu(1,1)-N(3))(2)](n) (1) are bridged by double mu(1,1) end-on (EO) azides into 1D zigzag coordination chains. Similar structural motifs, i.e. the chelation of abpt to the metal center and the double bridges of EO azides, are found in [Mn(4)(abpt)(4)(mu(1,1)-N(3))(8)(H(2)O)(2)] (2). The terminal aqua molecules and the monodentate N(3)(-) groups lead to the formation of a tetranuclear complex rather than a polymeric compound. The abpt underwent deamination in the presence of copper ions during the process of coordination and became 3,5-bis(pyridin-2-yl)-1,2,4-triazolate (bpt-H) in 3-5. [Cu(4)(bpt-H)(4)(N(3))(4)].4.5H(2)O (3) is a neutral tetranuclear grid-like complex, in which the azides act as monodentate ligands. A similar [Cu(4)(bpt-H)(4)](4+) grid-like unit was found in [Cu(4)(bpt-H)(4)(mu-btcH)Cl(2)].2H(2)O (4) and a pair of symmetry-related copper atoms are bridged by the mu-btcH(2)(-) coligand in a butterfly-shaped structure. In [Cu(2)(bpt-H)(mu(6)-btc)(H(2)O)](n) (5), the tetranuclear {Cu(4)(mu-bpt-H)(2)(mu(3)-carboxylate)(2)}(4+) units are bridged by mu(6)-btc(3-) ligands in a 2D step-like layer structure. Temperature-dependent magnetic susceptibility measurements reveal that the double mu(1,1)-N(3)(-) bridges in 2 transmit the ferromagnetic interactions between Mn(2+) centers (J(1) = J(2) = +3.09(4) cm(-1), g(Mn(II)) = 2.02(1)), and the mu-(bpt-H)(-) bridges transmit moderate antiferromagnetic interactions in both 3 (J = -12.78(13) cm(-1)) and 4 (J(1) = -14.96(11) cm(-1)). In 4 the antiferromagnetic coupling via the mu-btcH(2-) bridge was found as the second coupling pathway (J(2) = -9.48(7) cm(-1)). The coexistence of ferromagnetic and antiferromagnetic coupling between four Cu(2+) centers occurs in 5 (J(1) = -0.88(3) cm(-1) and J(2) = +5.01(2) cm(-1)). The magneto-structural relationship for tetranuclear copper pyrazolate/triazolate compounds has been discussed.
authors.affiliation: Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Zhao-Sha
authors.initials: ZS
authors.lastname: Meng
authors.forename: Lei
authors.initials: L
authors.lastname: Yun
authors.forename: Wei-Xiong
authors.initials: WX
authors.lastname: Zhang
authors.forename: Chao-Gang
authors.initials: CG
authors.lastname: Hong
authors.forename: Radovan
authors.initials: R
authors.lastname: Herchel
authors.forename: Yong-Cong
authors.initials: YC
authors.lastname: Ou
authors.forename: Ji-Dong
authors.initials: JD
authors.lastname: Leng
authors.forename: Meng-Xia
authors.initials: MX
authors.lastname: Peng
authors.forename: Zhuo-Jia
authors.initials: ZJ
authors.lastname: Lin
authors.forename: Ming-Liang
authors.initials: ML
authors.lastname: Tong
mesh_terms: D002104:Cadmium / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D008280:Magnetics; D008345:Manganese / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry*; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry; D011720:Pyrazoles / Q000737:chemistry; D014230:Triazoles / Q000737:chemistry*
chemical_list: D019216:Metals, Heavy; D011108:Polymers; D011720:Pyrazoles; D014230:Triazoles; D002104:Cadmium; C045575:1,2,4-triazole; D008345:Manganese; D003300:Copper