title: Effect of the semirigid capping ligand on the structure formation of cyano-bridged bimetallic assemblies: syntheses, crystal structures, and magnetic properties.
abstract: The syntheses, crystal structures, and magnetic properties of three novel cyano-bridged bimetallic assemblies, [Ni(bpm)(2)](3)[Co(CN)(6)](2)x3.5H(2)O (1), [Co(bpm)(2)][Fe(CN)(5)NO]x2H(2)O (2), and [Co(bpm)(2)][Ni(CN)(4)] (3) (bpm = bis(1-pyrazolyl)methane), are reported. Complex 1 crystallizes in the tetragonal space group P4(3)2(1)2 with a = 12.800(5) A, b = 12.800(5) A, c = 42.80(3) A, V = 7012(6) A(3), and Z = 8. Complex 2 crystallizes in the chiral trigonal space group P3(2)21 with a = 11.9961(19) A, b = 11.9961(19) A, c = 16.062(5) A, gamma = 120 degrees , V = 2001.7(8) A(3), and Z = 3. Complex 1 is a trigonal bipyramidal complex in which three [Ni(bpm)(2)](2+) units are situated in the equatorial plane and are connected to the two apical [Co(CN)(6)](3)(-) units via three N ends of the cyanide groups. Complex 2 possesses a triangular left-handed helical chain structure composed of [Co(bpm)(2)](2+) linked by [Fe(CN)(5)NO](2)(-); the shortest intramolecular Co...Fe distance is 5.162 A. To the best of our knowledge, this is the first observation of a heteronuclear helical chain structure based on pentacyanonitrosylferrate(II). The structure of complex 3 is roughly determined by X-ray crystallograhy analysis to be a 1D zigzag chain. These structure variations, from a discrete cluster to a 1D helical chain and a 1D zigzag chain, rely on the semirigidity of the capping ligand bpm. Magnetic susceptibility measurements indicate that complex 1 has an intramolecular ferromagnetic interaction (J = 4.06 cm(-)(1)) between the nickel(II) ions; this is further confirmed by the magnetization measurements. In complexes 2 and 3, the cobalt(II) ions are located in a moderately strong field.
authors.affiliation: Department of Chemistry, Nankai University, Tianjin 300071, People's Republic of China.
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.forename: Jun
authors.initials: J
authors.lastname: Xia
authors.forename: Peng
authors.initials: P
authors.lastname: Cheng
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
authors.forename: Hai-Bin
authors.initials: HB
authors.lastname: Song
authors.forename: Hong-Gen
authors.initials: HG
authors.lastname: Wang
authors.forename: Shi-Ping
authors.initials: SP
authors.lastname: Yan
authors.forename: Dai-Zheng
authors.initials: DZ
authors.lastname: Liao
authors.forename: Zong-Hui
authors.initials: ZH
authors.lastname: Jiang