The kinetics of the reactions between [Ni(bipy)(COD)] and bicyclopropylidene (bcp), dicyclopropylacetylene (dcpa) and 1,4-dimethoxy-2-butyne (dmbu) were investigated using stopped-flow techniques. Similar to previous studies the results support an associative mechanism (activation parameters for bcp: ΔH # = 46 � 2 kJ • mol À 1 and ΔS # = À 69 � 8 J • mol À 1 • K À 1) and therefore allowed to postulate a more general reaction mechanism for the reaction pathway. The products, the nickel(0) complexes [Ni(bipy)(bcp)] and [Ni(bipy)(dcpa)], could be structurally characterized and the molecular structures are presented. In addition, the corresponding copper(I) complexes [Cu(bipy)(bcp)]PF 6 and [Cu(bipy)(dcpa)]PF 6 were also structurally characterized and their reactivity towards dioxygen was investigated. A detailed discussion of the structural properties and comparisons to similar literature-known olefinic complexes with transition metals are presented.

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The Cover Feature shows the alkene Bicyclopropylidene (bcp) that became (as well as its derivatives) a versatile C6 building blocks for organic synthesis. It can undergo co‐cyclizations under palladium, nickel, and cobalt catalysis. However, despite the fundamental interest in the mechanism of these reactions, so far only a small number of transition metal complexes with bcp as ligand have been isolated and structurally characterized. Herein, we report the molecular structures of the nickel and copper complexes – [Ni(bipy)(bcp)] [Cu(bipy)(bcp)]PF6 (anion not shown) – with bcp and 2,2′‐bipyridine as a co‐ligand. More information can be found in the Full Paper by A. de Meijere, S. Schindler et al.