Reaction of N,N′-bridged 1,10-diazacyclooctadeca-5,14-diynes with [CpCo(cod)]: a new type of superphane

Abstract

The reaction of N,N′-bridged 1,10-diazacyclooctadeca-5,14-diynes 1a–d with [CpCo(cod)] (2) leads to both intra- (3) and inter-molecular (4) CpCo–cyclobutadiene complexes. The yield of intramolecular complex decreases and the yield of intermolecular complex increases with growing length of the alkane bridge. X-Ray investigations on single crystals of 3a, 3d and 4d reveal that the repulsions between the Cp ring and two CH₂-groups in β-position to the cyclobutadiene ring increase from 3a to 3d. Such steric repulsions are not found in 4d.