The synthesis, structures and magnetic characterisation of a family of discrete planar pentanuclear Cu(II) 12-MC-4 metallacrowns of formulae [Cu5(L1)4(MeOH)4](ClO4)2 (1), [Cu5(L1)4(py)2](ClO4)2·py (2), [Cu5(L1)4(py)6](ClO4)2 (3) and [Cu5(L2)4(MeOH)4](ClO4)2·H2O (7) (where L1H2 = 2-(dimethylamino)phenylhydroxamic acid and L2H2 = 2-(amino)phenylhydroxamic acid) are reported. UV-vis and Electrospray MS studies indicate solution stability with respect to their Cu5(L)4}2+ cores. Magnetic susceptibility measurements confirm strong antiferromagnetic exchange between the Cu(II) ions resulting in isolated S = 1/2 ground spin states. The introduction of ditopic co-ligands such as 4,4′-bipyridine (4,4′-bipy), pyrazine (pz) and 4,4′-azopyridine (4,4′-azp) results in their coordination at a number of axial Cu(II) sites within the Cu5} metallacrown nodes to afford the extended networks [Cu5(L1)4(4,4′-bipy)3](ClO4)2·(H2O)}n (4), [Cu5(L1)4(4,4′-azp)2(MeOH)2](ClO4)2}n (5) and [Cu5(L2)4(pz)2(MeOH)3](ClO4)2·MeOH}n (6).
一系列离散平面五核 Cu(II) 12-MC-4
金属冠的合成、结构和磁性表征,这些
金属冠的
化学式分别为[Cu5(L1)4(MeOH)4](
ClO4)2 (1)、[Cu5(L1)4(py)2]( )2-py (2)、报告了[Cu5(L1)4(py)6]( )2 (3) 和 [Cu5(
L2)4(MeOH)4]( )2-
H2O (7)(其中 L1H2 = 2-(二甲基
氨基)苯基羟
肟酸,
L2H2 = 2-(
氨基)苯基羟
肟酸)。紫外可见光和电喷雾质谱研究表明,它们的Cu5(L)4}2+核心具有溶液稳定性。磁感应强度测量结果证实,Cu(II) 离子之间存在强烈的反
铁磁交换,从而形成了孤立的 S = 1/2 地面自旋态。引入 4,4′-联
吡啶 (4,4′-bipy)、
吡嗪 (pz) 和 4,4′-氮杂
吡啶 (4,4′-azp)等二价共配位体后,它们在Cu5}
金属冠节点内的多个轴向 Cu(II) 位点配位,形成扩展网络 [Cu5(L1)4(4、4′-bipy)3]( )2-( )}n (4)、[Cu5(L1)4(4,4′-azp)2(MeOH)2]( )2}n (5) 和 [Cu5(
L2)4(pz)2(MeOH)3]( )2-MeOH}n (6)。