The synthesis and crystal structures of pyridine-2,6-dicarboxamide oxime, C7H9N5O2, and its nickel(II) and copper(II) co-ordination compounds

Abstract

The crystals of pyridine-2,6-dicarboxamide oxime, C ₇ H ₉ N ₅ O ₂ , are monoclinic, space group P2 ₁ with a = 7.569(1), b = 4.695(1), c = 12.534(2) Å, β = 106.50(2)° and Z = 2. The reaction of the ligand with nickel(II) sulfate hexahydrate yielded purple crystals of formula [Ni(C ₇ H ₉ N ₅ O ₂ ) ₂ ] [SO ₄ ]·5H ₂ O which crystallized in the triclinic space group P1 with a = 7.502(1), b = 11.493(2), c = 15.526(1) Å, α = 104.60(1)°, β = 101.91(6)°, γ = 97.35(1)° and Z = 2. The reaction of the ligand with copper(II) sulfate pentahydrate resulted in a green crystalline complex of formula [{Cu(C ₇ H ₉ N ₅ O ₂ )(SO ₄ )}·2H ₂ O] _n which crystallized in the monoclinic space group P2 ₁ /n with a = 10.427(3), b = 8.876(2), c = 13.777(4) Å, β = 93.254(1)° and Z = 4. The nickel complex consists of discrete [Ni(C ₇ H ₉ N ₅ O ₂ ) ₂ ] ²⁺ cations and sulfate anions, the cation existing in a slightly distorted octahedral complex with bonding through the heterocyclic and oxime nitrogen atoms. The copper complex consists of a two-dimensional polymeric chain of Cu(C ₇ H ₉ N ₅ O ₂ ) units connected by bridging sulfate groups.