Metalloporphines: Dimers and Trimers

Procedures for the purification and subsequent crystallization of the slightly soluble four-coordinate metallporphines, the simplest possible porphyrin derivatives, are described. Crystals of the porphine derivatives of cobalt­(II), copper­(II), platinum­(II), and two polymorphs of zinc­(II) were obtained. Analysis of the crystal and molecular structures shows that all except the platinum­(II) derivative form an unusual trimeric species in the solid state. The isomorphous cobalt­(II), copper­(II), and one zinc­(II) polymorph pack in the unit cell to form dimers as well as the trimers. Interplanar spacings between porphine rings are similar in both the dimers and trimers and range between 3.24 and 3.37 Å. Porphine rings are strongly overlapped with lateral shifts between ring centers in both the dimers and trimers with values between 1.52 and 1.70 Å or in Category S as originally defined by Scheidt and Lee. Periodic trends in the M–Np bond distances parallel those observed previously for tetraphenyl- and octaethyl­porphyrin derivatives.

本文阐述了微溶性四配位金属卟啉（metallporphines）——结构最为简单的卟啉衍生物——的纯化与后续结晶实验流程。我们成功制备得到钴(II)、铜(II)、铂(II)的卟吩衍生物晶体，以及锌(II)卟吩衍生物的两种多晶型样品。晶体与分子结构分析结果表明，除铂(II)衍生物外，其余金属卟啉在固态下均会形成非常规的三聚体结构。同构的钴(II)、铜(II)及其中一种锌(II)多晶型在晶胞内同时形成二聚体与三聚体结构。卟吩环之间的面间距在二聚体与三聚体中均处于3.24至3.37 Å范围内，二者数值相近。二聚体与三聚体中的卟吩环均发生显著重叠，环中心之间的侧向位移介于1.52至1.70 Å之间，属于Scheidt与Lee最初定义的S类（Category S）堆叠模式。金属-卟吩氮（M–Np）键长的周期变化规律与此前报道的四苯基卟啉及八乙基卟啉衍生物的相关规律一致。