Nickel thioether chemistry: syntheses of nickel(II) complexes of tetra- and penta-thia macrocyclic ligands. The single-crystal structures of [Ni([16]aneS4)(OH2)2][BF4]2 and [Ni([15]aneS5)][PF6]2([16]aneS4=1,5,9,13-tetrathiacyclohexadecane, [15]aneS5=1,4,7,10,13-pentathiacyclopentadecane)
Abstract
Treatment of [Ni(OH2)6][BF4]2 with 1 molar equivalent of [12]aneS4([12]aneS4= 1,4,7,10-tetrathiacyclododecane) or [16]aneS4([16]aneS4= 1,5,9,13-tetrathiacyclohexadecane) in MeNO2 in the presence of acetic anhydride for 30 min affords blue solutions from which the complexes [Ni([12]aneS4)(OH2)2]2+ and [Ni([16]aneS4)(OH2)2]2+ can be isolated. The complex [Ni([16]aneS4)(OH2)2][BF4]2 crystallises in the triclinic space group P, with the octahedral nickel atom lying on a crystallographic centre of symmetry, the aqua ligands mutually trans, Ni–S 2.4290(10), 2.4231(10), Ni–O 2.083(3)Å, and the macrocycle co-ordinated in the equatorial plane. Treatment of [Ni(OH2)6][BF4]2 or [Ni(OH2)6][PF6]2 with [15]aneS5 in MeNO2 in the presence of acetic anhydride affords purple solutions of the complex [Ni([15]aneS5)]2+. A single-crystal structure determination on [Ni([15]aneS5)][PF6]2, which crystallises in the monoclinic space group P21, shows the cation to adopt a square-pyramidal geometry, Ni–Sapical 2.413(5), Ni–Sbasal 2.146(7), 2.169(6), 2.177(6), 2.198(6)Å. The complex cation [Ni([15]aneS5)]2+ forms six-co-ordinate adducts with MeCN, pyridine and chloride.