Lewis-Base Adducts of Lead(II) Compounds. XV. Synthesis and Structure of Some Adducts of Bis(2-pyridyl)amine With Lead(II) Salts

Abstract

Several complexes of bis(2-pyridyl)amine ('dpa') with lead(II) salts have been synthesized and subjected to room-temperature single-crystal X-ray studies. 1:1 Adducts have been obtained with lead(II) bromide and iodide. They have similar unit cells, also similar to those of a variety of other N,N′-heteroaromatic bidentate ligand adducts with metal(II) halides, and the C2/c cell described elsewhere in this series may be regarded as archetypical. [(dpa)PbBr₂](∞|∞) is monoclinic, P2₁/a, a 9.791(4), b 9.720(4), c 16.498(4) Ǻ, β 95.96(4)′, Z = 4 f.u.; conventional R on |F| at convergence was 0.066 for N_o = 2717 'observed' (I > 3σ(I)) reflections. [(dpa)PbI₂](∞|∞) is monoclinic, P2₁/c, a 8.299(2), b 10.229(3), c 16.905(5) Ǻ, β 101.47(2)°, Z = 4 f.u.; R was 0.044 for N_o 2140. Both complexes, like their 2,2'-bipyridine and 1,10-phenanthroline analogues, are linear polymers with six-coordinate (cis-N₂)Pb(μ-X)₄ environments linked in infinite ... (μ-X)₂Pb(μ-X)₂… one-dimensional chains, and with dpa being bidentate. A 2:1 adduct of bis(2-pyridyl)amine with lead(II) acetate ('Pb(ac)₂') is also described. [(dpa)₂Pb(ac)₂](∞|∞) is monoclinic, C 2/c, a 28.835(5), b 10.868(3), c 7.665(2) Ǻ, β 94.21(2)°, Z = 4; R was 0.029 for N_o 1854. The complex is a linear polymer along c; the lead atom lies on a crystallographic twofold axis with a coordination environment comprising a pair of symmetry-related dpa ligands, in this case unidentate (Pb-N 3.092(6) Ǻ), and a pair of symmetry-related bidentate acetate ligands (Pb-O 2.465(4) and 2.568(5) Ǻ) with the first oxygen atom performing an additional bridging function to adjacent symmetry-related lead atoms (Pb-O 2.663(4)Ǻ).