Cyclic polyamines via a molybdenum(0) templated Mannich-type reaction

Reaction of [Mo(CO)3(3-azahexane-1,6-diamine)] with formaldehyde and the carbon acid nitroethane leads to cyclisation involving one terminal amine and either the internal secondary amine (minor product) or the other terminal primary amine (major product), with zinc/acid reduction yielding new cyclic tetraamines, also characterised as their cobalt(III) complexes. This is the first example of Mannich-style formation of a pendant-arm triazamacrocycle around a molybdenum(0) template. The unexpected N-(1′-aminopropyl)-6-methyl-1,4-diazacycloheptan-6-amine minor product has been characterised by an X-ray structure as its cis-dichlorocobalt(III) complex.