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Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for 2: 1 adducts of the N,N′-bidentate aromatic base 2,2′-bipyridine (' bpy ') with lead(II) nitrate and perchlorate. [( bpy )2Pb(NO3)2]2 is triclinic, Pī , a 14.609(6), b 9.400(4), c 8.396(4) Ǻ, α 71.10(3), β 83.53(3), γ 81.72(3)°, Z = 1 dimer; R was 0.037 for No = 3001 independent, 'observed' (I > 3σ(I)) reflections. [( bpy )2Pb(ClO4)2] is monoclinic, P21/c, a 9.8806(6), b 12.198(6), c 19.924(2) Ǻ, β 106.80(1)°, Z = 4, R 0.040 for No 4456. Unlike the two 1,10-phenanthroline (' phen ') systems which are mononuclear with eight-coordinate PbN4O4 environments incorporating a pair of O,O′;- bidentate anions, the bpy systems are centrosymmetric dimers; in each case the coordination environment incorporates a pair of N,N′- bidentate aromatic bases and an O,O′- bidentate anion, but the other anion is not only O,O′- bidentate, but also bridges by a third oxygen atom to the other lead atom so that it is nine-coordinate PbN4O5. Syntheses and room-temperature single-crystal X-ray structure determinations are also recorded for a pair of 2:1 adducts of 2,2?-bipyridine with lead(II) salts of mixed anion stoichiometry , viz. ( bpy )2PbX(ClO4), X = acetate ('ac'), chloride. [( bpy )2Pb(ac)(ClO4)] is triclinic, Pī , a 15.910(6), b 9.067(5), c 8.588(3) Ǻ, α 102.91(4), β 93.64(3), γ 103.41(4)°, Z = 2, R 0.039 for No 5283. [( bpy )2PbCl(ClO4)2 is monoclinic, P 21/c, a 12.923(2), b 8.759(2), c 19.650(2) Ǻ, β 94.776(9)°, Z = 2 dimers (R 0.037 for No 4433). Like the 1:2 oxoanion/phen adducts, the acetate is a discrete molecular species with an eight-coordinate PbN4O4 lead environment, the oxygen array comprising a pair of O,O′- bidentate perchlorate and acetate ligands. The chloride adduct, however, is like the 1:2 oxoanion/bpy adducts, being centrosymmetric binuclear, a pair of μ-chloride ions linking the two lead atoms which have seven-coordinate PbN4(μ- Cl )2O lead environments, the perchlorate species being O-unidentate. |
