Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture (Angew. Chem. Int. Ed. Engl. 9/1991)
The cover picture shows the carbon-metal framework in the dimetal-sandwich compound bis(η5-pentamethylcyclopentadienyl)dicobalt—reminiscent of the double-cone structure of metallocenes proposed by E. O. Fischer. The two cones are linked via a Co=Co double bond (2.253 Å, blue), which is stable without bridging ligands. Each Co atom thus achieves a 16-VE configuration. More about this prototype of a new class of sandwich compounds and about further products which are formed upon cocondensation of pentamethylcyclopentadiene and cobalt are reported in a communication by J. J. Schneider et al. on p. 1124 ff (see also Highlight on p. 1120).