The crystal structures of six cobalt sandwich complexes—four in the η5-cyclopentadienyl/η4-cyclobutadiene family, two from the related η5-cyclopentadienyl/η4-cyclopentadienone family—are presented and discussed alongside related structural precedents. In each of the complexes an undecorated cyclopentadienyl ligand is present whereas the partner cyclobutadiene or cyclopentadienone ligand bears four identical aromatic substituents (phenyl, p-tolyl, p-fluorophenyl, 2-thienyl or 2,2′-bithienyl). This range of substituents allows for detailed structural comparison between members of the families of sandwich complexes presented here, and with previously reported structures. Crystal structures of members of the η5-cyclopentadienyl/η4-tetraarylcyclobutadiene (left) and η5-cyclopentadienyl/η5-cyclopentadienone (right) families of sandwich complexes are presented.

中文翻译：

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η5-环戊二烯基/η4-环丁二烯和η5-环戊二烯基/η4-环戊二烯酮家族中钴夹心配合物的晶体结构

六种钴夹心配合物的晶体结构——四个在 η5-环戊二烯基/η4-环丁二烯家族中，两个来自相关的 η5-环戊二烯基/η4-环戊二烯酮家族——与相关的结构先例一起呈现和讨论。在每个配合物中都存在未修饰的环戊二烯基配体，而配对的环丁二烯或环戊二烯酮配体带有四个相同的芳族取代基（苯基、对甲苯基、对氟苯基、2-噻吩基或 2,2'-联噻吩基）。这一范围的取代基允许在此处介绍的夹心复合物家族成员之间进行详细的结构比较，并与以前报道的结构进行比较。