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首页> 外文期刊>Polyhedron: The International Journal for Inorganic and Organometallic Chemistry >Mononuclear Cu and dinuclear Cu-Ln complexes of benzimidazole based ligands including N and O donors: Syntheses, characterization, X-ray molecular structures and magnetic properties
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Mononuclear Cu and dinuclear Cu-Ln complexes of benzimidazole based ligands including N and O donors: Syntheses, characterization, X-ray molecular structures and magnetic properties

机译：苯并咪唑基配体（包括N和O供体）的单核Cu和双核Cu-Ln配合物：合成，表征，X射线分子结构和磁性

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摘要

The synthesis of two mononuclear precursor copper complexes, [(HL ~2)_2Cu], 1, and [(HL~3)_2Cu] ·H_2O,2, and three dinuclear Cu-Ln complexes, [(HL ~1)_2Cu(CH_3CN)_2Gd(NO_3) _3], 3, [(HL~3)_2CuGd(NO_3) _3]·2(H_2O) 4, and [(HL~3) _2CuTb(NO_3)_3]·2(H_2O), 5, based on the ligands H_2L~1 (4-bromo-2-[1-(5-bromo-2-hydroxy- 3methoxybenzyl)-1H-benzimidazol-2-yl]-6-methoxyphenol), H_2L ~2 (2-(1H-benzimidazol-2-yl)-4-bromo6-methoxyphenol) and H _2L~3 (2-(1H-benzimidazol-2-yl)-6-methoxyphenol) are described in this contribution. The X-ray crystal structures of H _2L~2, 1, 3, 4, and S have been solved. The novel ligand H_2L~2 crystallizes with two independent molecules in the asymmetric unit; several intermolecular hydrogen contacts connect alternate independent H_2L~2 molecules into chains developing along c. In complex 1, two (HL~2)~- ligands chelate the copper ion through their imidazolyl nitrogen and phenoxo oxygen atoms, in a relative head to tail arrangement. The molecular structure of 3 is similar to those of the previously reported Cu-Ln complexes OF H_2L~1. In the isostructural complexes 4 and 5, two HL~3 ligands sandwich one Cu ~(2+) ion through their N,O sites and one Ln~(3+) ion through their O_2 site, implying a relative head to head arrangement, at variance with the relative head to tail arrangement of HL~2 in the mononuclear copper precursor 1. The magnetic properties of 1, 3,4, and 5 have been investigated. Extended intermolecular antiferromagnetic interactions operate in complex 1 (U_(chain)= -0.8(1) cm~(-1)). Ferromagnetic interactions between Gd (S = 7/2) and Cu (S =1 /2) centers operate in complexes 3 and 4, leading to an S - 4 ground state (J_(CuGd) - 7.2(2) cm~(- 1) for 3 and J_(CuGd)- 6.5(2) cm~(-1) for 4). Depopulation of the Tb Stark levels, preclude obtaining reliable information on the presence and sign of the Cu-Tb interaction in 5. These new complexes are complementary to those previously reported: the Cu-O_2-Gd core is planar while deformations are borne by the ligands at variance with previous examples where the constraints were located at the Cu-O_2-Gd core. The presence of two independent ligands in the Cu,Gd coordination spheres confers a degree of freedom greater than that allowed by a unique tetradentate ligand. As a result, the strength of the magnetic interaction is not solely related to the dihedral angle between the CuOO and GdOO planes in the central core.
机译：两种单核前体铜配合物[（HL〜2）_2Cu]，1和[（HL〜3）_2Cu]·H_2O，2的合成，以及三种双核Cu-Ln配合物[（HL〜1）_2Cu（ CH_3CN）_2Gd（NO_3）_3]，3，[（HL〜3）_2CuGd（NO_3）_3]·2（H_2O）4和[（HL〜3）_2CuTb（NO_3）_3]·2（H_2O），5 ，基于配体H_2L〜1（4-溴-2- [1-（5-溴-2-羟基-3甲氧基苄基）-1H-苯并咪唑-2-基] -6-甲氧基苯酚），H_2L〜2（2-在该文献中描述了（1H-苯并咪唑-2-基）-4-溴6-甲氧基苯酚和H _2L〜3（2-（1H-苯并咪唑-2-基）-6-甲氧基苯酚）。解决了H _2L〜2、1、3、4和S的X射线晶体结构。新的配体H_2L〜2在不对称单元中以两个独立的分子结晶。几个分子间氢接触将交替的独立H_2L〜2分子连接成沿c形成的链。在配合物1中，两个（HL〜2）〜-配体通过它们的咪唑基氮原子和苯氧基氧原子螯合铜离子，相对的头对尾排列。 3的分子结构与先前报道的H_2L〜1的Cu-Ln配合物相似。在同构配合物4和5中，两个HL〜3配体通过其N，O位点夹着一个Cu〜（2+）离子，并通过它们的O_2位点夹着一个Ln〜（3+）离子，这意味着相对的头对头排列，与单核铜前体1中HL〜2的相对头尾排列有关。研究了1，3,4，和5的磁性。扩展的分子间反铁磁相互作用在复合物1中起作用（U_（chain）= -0.8（1）cm〜（-1））。 Gd（S = 7/2）和Cu（S = 1/2）中心之间的铁磁相互作用在配合物3和4中起作用，从而导致S-4基态（J_（CuGd）-7.2（2）cm〜（- 1）适用于3，J_（CuGd）-6.5（2）cm〜（-1）适用于4）。 Tb Stark水平的减少，使得无法获得有关5中Cu-Tb相互作用的存在和迹象的可靠信息。这些新的配合物与先前报道的配合物是互补的：Cu-O_2-Gd核心是平面的，而变形则由约束条件位于Cu-O_2-Gd核心的以前的例子中，其配体有所不同。 Cu，Gd配位球中存在两个独立的配体，其自由度大于唯一的四齿配体所允许的自由度。结果，磁性相互作用的强度不仅与中心芯中的CuOO和GdOO平面之间的二面角有关。

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