The crystal structure of the cis isomer of cis-bis(l-DOPA-κ²N,O)copper(II) monohydrate (l-DOPA is 3,4-dihydroxy-l-phenylalanine) (CuLD), [Cu(C₉H₁₀NO₄)₂]·H₂O, is a singular example of a structurally characterized, homoleptic, crystalline metal l-DOPA complex. CuLD crystallizes in the space group P2₁, with Z′ = 2. The two independent molecules are square planar, and are interconnected by a linear hydrogen-bonded chain containing 12 independent hydrogen bonds. The copper ions in both molecules have weak apical intermolecular Cu…O interactions [2.739 (2) and 2.973 (2) Å] with catechol –OH groups. A survey of the Cambridge Structural Database suggested that cis and trans isomers of Cu(NH₂–C–CO₂)₂ amino acid complexes are equally likely to occur. 12 strong O—H…O and N—H…O hydrogen bonds stabilize an unusual linear arrangement of the Cu complexes. The Cu…Cu′ distances along the chain are nearly equal [5.0739 (3) and 5.1107 (3) Å] and the Cu…Cu′…Cu angles are nearly linear [176.75 (1)°]. The MATCH procedure available in the Oxford University Crystals for Windows package was used to carry out a detailed analysis of the relationship between the two independent molecules. MATCH has some particular advantages in studying the details of pseudosymmetry, which include: (i) no atomic-order requirements; (ii) the pseudosymmetry matrix is readily available, which allows quick insight into the symmetry elements involved and their location; and (iii) the differences between molecular centroids, as well as between all atomic positions and torsion angles, are listed. A tutorial presentation is designed to attract new users to the technique. In the present case, a search for a pseudosymmetric relationship between the two independent molecules showed that they are related by a pseudo-4₂ axis along the crystallographic c direction. A detailed analysis shows that the pseudo-4₂ symmetry is disrupted by torsions about the CH₂—C(ipso) bonds, and that there is no supergroup that can be used to describe the crystal structure.

中文翻译：

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cis-Bis(l-DOPA-κ2N,O)copper(II) monohydrate：合成、晶体结构和假对称性分析方法

所述的晶体结构的顺式异构体的顺式-双（升-DOPA-κ ² Ñ，ö）铜（II）一水合物（升-DOPA是3,4-二羟基-升-苯丙氨酸）（CuLD），[铜（C ₉ H ₁₀ NO ₄ ) ₂ ]·H ₂ O 是具有结构特征的、均配的、结晶金属l- DOPA 络合物的一个单一实例。CuLD在空间群P 2 _{1 中}结晶，其中Z' = 2。两个独立的分子是方形平面，并通过包含 12 个独立氢键的线性氢键链相互连接。两个分子中的铜离子与邻苯二酚-OH 基团具有弱的顶端分子间 Cu…O 相互作用 [2.739 (2) 和 2.973 (2) Å]。剑桥结构数据库的一项调查表明，Cu(NH ₂ –C-CO ₂ ) _{2 的}顺式和反式异构体氨基酸复合物同样可能发生。12 个强 O-H...O 和 N-H...O 氢键稳定了 Cu 配合物的不寻常线性排列。沿着链的 Cu…Cu' 距离几乎相等 [5.0739 (3) 和 5.1107 (3) Å]，Cu…Cu'…Cu 角度几乎是线性的 [176.75 (1)°]。牛津大学Crystals for Windows 中提供的 MATCH 程序包被用来对两个独立分子之间的关系进行详细分析。MATCH 在研究伪对称的细节方面有一些特别的优势，包括： (i) 没有原子序要求；(ii) 伪对称矩阵很容易获得，可以快速了解所涉及的对称元素及其位置；(iii) 列出了分子质心之间以及所有原子位置和扭转角之间的差异。教程演示旨在吸引新用户使用该技术。在本案例中，对两个独立分子之间伪对称关系的研究表明，它们通过沿晶体学c的伪 4 ₂轴相关方向。详细分析表明，关于CH ₂ -C( ipso ) 键的扭转破坏了伪4 ₂对称性，并且没有可用于描述晶体结构的超群。