Synthesis and Crystal Structures of Novel Zn(II) and Ni(II) Coordination Polymers with 1,4-bis(3-pyridyl)-2,3-diazo-1,3-butadiene Ligands

Institute of Organic and Polymeric Materials, National Taipei University of Technology
â—‹Gene-Hsiang Lee Hsin-Ta Wang

Two novel coordination polymers with 1D metal-organic frameworks (MOFs) have been synthesized by reacting 1,4-bis(3-pyridyl)-2,3-diazo-1,3-butadiene (L) with zinc dichloride. Both compounds have the same repeating unit [ZnLCl2]n of a distorted tetrahedral Zn(II) center coordinated by two chlorides and two pyridyl nitrogen atoms of two bridging bismonodentate ligands. These two complexes show different structural conformations, with one forming a helical chain crystallized in an orthorhombic space group Pna21 with a = 7.9652(3), b = 21.4716(7), c = 8.2491(3)Å, V = 1410.81(9) Å 3 and Z = 4 and the other producing a square-wave chain crystallized in a monoclinic space group P21/n with a = 9.1752(3), b = 14.5976(4), c = 10.3666(3) Å , β = 98.231(2)o, V = 1374.16(7) Å 3 and Z = 4. When Ni(NO3)2 was used instead of ZnCl2 under the same reaction conditions, a new 3D metal-organic coordination polymer, [Ni2(L)3(NO3)4.EtOH]n was obtained. This compound shows the monoclinic system, space group P21/c with a = 16.3181(10), b = 14.9976(8), c = 19.6917(11)Å, β = 98.360(2)o, V = 4768.0(5)Å3, Z = 4. The Ni(II) ion lies in the distorted octahedral environment with three bridging ligands and two nitrate anions, and also an ethanol guest molecule occupies of a ca. 6.7 x 8.5Å2 cavity.