Neutral Cu4N12 and Ag4N12 metallacycles with a para-cyclophane framework assembled from copper(I) and silver(I) pyrazolates and pyridazine

Trinuclear copper( I) and silver( I) pyrazolates {[ 3,5( CF3)(2)Pz] M}(3) (M = Cu and Ag) react with pyridazine to give neutral, tetranuclear metallacycles with a para-cyclophane core whereas benzo[ c] cinnoline fails to break the cyclic pyrazolate trimers under similar conditions, and affords a metallapropellane featuring both two- and three-coordinatemetal sites.