Butterfly topologies: new expanded carbon-rich organometallic scaffolds

Starting from either (tetraethynylcyclobutadiene)cyclopentadienylcobalt or [1,2-diethynyl-3,4-(2-dioxanyl)cyclobutadiene]cyclopentadienylcobalt a sequence of copper and Pd-catalyzed couplings of the Eglinton and the Heck–Cassar–Sonogashira–Hagihara type furnishes five bow-tie shaped doubly annelated dehydroannulenes, the largest of which featuring a (formal) 7,8:13,14:25,26:31,32-tetra(4′alkyl-1′,2′-benzo)tricyclo[18,16,02,19]hexatricosa-3,5,9,11,15,17,21,23,27,29,33,35-dodecayne-1,7,13,19,25,31-hexaene hydrocarbon ligand with a cyclopentadienyl-cobalt stabilized cyclobutadiene complex as its central unit. Single crystal X-ray structures of two of the smaller butterflies are reported and their surprising solid-state packing is discussed herein.