Metal Ion Interactions with Pyridinecarboxylates in Tripodal tris(2-Aminoethyl)amine Ligand System: Crystal Structures of [Ni(tren)(pic)]2(ClO4)2·CH3OH and [Co(tren)(dipic)]ClO4·CH3OH

Abstract

Two new complexes [Ni(tren)(pic)]2(ClO4)2·CH3OH (1) and [Co(tren)(dipic)]ClO4·CH3OH (2), (tren is tris(2-aminoethyl)amine, pic is the anion of picolinic acid, dipic is the dianion of 2,6-pyridinedicarboxylic acid) have been synthesized and structurally characterized. X-ray analysis indicates that the two complexes are mononuclear with tren acting as a quadridentate ligand. In complex 1, the nickel(II) ion is further coordinated with picolinate in μ2-N, O bidentate chelating mode. In complex 2, the cobalt(III) ion is coordinated with the pyridine nitrogen and one carboxylic oxygen of 2,6-pyridinedicarboxylate in μ2-N, O chelating form. The metal atoms in both cases have distorted octahedral geometry. Crystal data: [Ni(tren)(pic)]2(ClO4)2·CH3OH (1), Mr = 869.03, monoclinic, C2/c, a = 26.354(5) A, b = 10.407(2) A, c = 25.839(5) A, β = 96.24(3)°, Z = 8, V = 7045(2) A3, R 1 = 0.0418, wR 2 = 0.1063 [I > 2σ(I)]; [Co(tren)(dipic)]ClO4·CH3OH (2), Mr = 501.77, Triclinic, P-1, a = 8.3667(2) A, b = 10.4434(2) A, c = 11.9431(16) A, α = 73.9590(10)°, β = 88.0240(10)°, γ = 75.5890°, Z = 2, V = 969.97(4) A3, R 1 = 0.0408, wR 2 = 0.1063 [I > 2σ(I)]. Two ternary transition metal complexes, [Ni(tren)(pic)]2(ClO4)2·CH3OH (1) and [Co(tren)(dipic)]ClO4·CH3OH (2) have been synthesized and structurally characterized.