Reactions of 1,8-diheterocyclotetradeca-4,11-diynes with (eta(4)-cycloocta-1,5-diene)(eta(5)-cyclopentadienyl)cobalt

The following monocyclic and bicyclic 14-membered diynes were treated with [CpCo(cod)]: 1-oxacyclotetradeca-4,11-diyne (2), 1,8-dioxacyclotetradeca-4, 11-diyne (3), cyclotetradeca-4,11-diynone (4), cyclotetradeca-4,11-diyne-1, 8-dione (5), 1,1,8,8-tetramelhyl-1,8-disilacyclotetradeca-4,11-diyne (6), 1 -allyl-1-azacyclotetradeca-4,11diyne (7), 1,8-dipropyl-1,8-diazacyclotetrad eca-1,11-diyne (8), diazacyclotetradeca-4,11-diyne (9), 1,8-diazabicyclo[6. 6.4]octadeca-4,11-diyne (10), 1,8-diazabicyclo[6.6.6]eicosa-4, 11diyne (11) , 1,10-diazabicyclo[8.6.6]docosa-13,19-diyne (12) and 1,12-diazabicyclo[10. 6.6]tetracosa-15,21-diyne (13). In all cases we obtained an intramolecular cyclobutadiene complex stabilized with a CpCo fragment (15-26). For 3 we co uld isolate, besides the cyclobutadiene complex 16, the trimerization produ ct 28. In the cases of 15, 16, 18, 20, 23, 25, and 26 the structure of the cylobutadiene complexes could be confirmed by X-ray studies. Common to all structures is a boat-like conformation of the tricyclic unit containing the cyclobutadiene ring. The two cycloheptene units adopt a chair conformation in which the heteroatom is removed from the metal center.