Zhong Chang, Zhao Min, Stern Charlotte, Barrett Anthony G M, Hoffman Brian M
Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA.
Inorg Chem. 2005 Nov 14;44(23):8272-6. doi: 10.1021/ic050788s.
We report the synthesis and physical studies of a novel porphyrazine (pz) dimer [1[Ni,Cu]]2, which has Ni(II) ions incorporated into the pz cores and is linked by two Cu(II) ions coordinated to bis(picolinamide) chelates attached to the pz periphery. [1[Ni,Cu]]2 was prepared from precursor pz 2 with a selenodiazole ring fused to the pz core. This ring was deprotected to form the diamino-pz 3, which reacted with 2 mol of picolinoyl chloride hydrochloride to form pz 1[2H,2H], with peripheral bis(picolinamide) chelates; this was metalated to form [1[Ni,Cu]]2. The crystal structures of 1[2H,2H] and [1[Ni,Cu]]2 are presented. The latter is a dimer in which parallel, face-to-face pz's with an average separation of 3.30 angstroms are linked through the peripheral picolinamide ligands by a pair of peripheral Cu(II) ions. Each Cu(II) is coordinated with distorted square-planar geometry by a picolinamide from each pz. In this report, we focus on the interaction of these two peripheral Cu(II) ions. We discuss the preparation and magnetic properties of the pz dimer complex [1[Ni,Cu]]2 with two Cu(II) ions in the peripheral chelate but a diamagnetic metal ion Ni(II) in the pz core. Although [1[Ni,Cu]]2 contains two Cu(II) ions (S = 1/2), we could detect no electron paramagnetic resonance signal, which suggests very strong antiferromagnetic exchange between those two Cu(II) ions. Temperature-dependent magnetic susceptibility measurement gives an exchange splitting between the S = 0 ground state and the excited triplet state of delta = 660 cm(-1).
我们报道了一种新型卟吩嗪（pz）二聚体[1[Ni,Cu]]2的合成及物理研究，该二聚体的pz核中含有Ni(II)离子，并通过两个与连接在pz外围的双（吡啶甲酰胺）螯合物配位的Cu(II)离子相连。[1[Ni,Cu]]2由前体pz 2制备而成，pz 2的pz核上稠合有一个硒二唑环。该环经脱保护形成二氨基-pz 3，其与2摩尔的盐酸吡啶甲酰氯反应形成具有外围双（吡啶甲酰胺）螯合物的pz 1[2H,2H]；将其金属化形成[1[Ni,Cu]]2。给出了1[2H,2H]和[1[Ni,Cu]]2的晶体结构。后者是一种二聚体，其中平均间距为3.30埃的平行、面对面的pz通过一对外围Cu(II)离子经由外围吡啶甲酰胺配体相连。每个Cu(II)由来自每个pz的一个吡啶甲酰胺以扭曲的平面正方形几何构型配位。在本报告中，我们关注这两个外围Cu(II)离子的相互作用。我们讨论了pz二聚体配合物[1[Ni,Cu]]2的制备及磁性，该配合物在其外围螯合物中有两个Cu(II)离子，但在pz核中有一个抗磁性金属离子Ni(II)。尽管[1[Ni,Cu]]2含有两个Cu(II)离子（S = 1/2），但我们未检测到电子顺磁共振信号，这表明这两个Cu(II)离子之间存在非常强的反铁磁交换。变温磁化率测量给出了S = 0基态与激发三重态之间的交换分裂，δ = 660 cm(-1)。
