1,4,7-Triazacyclononane


1,4,7-Triazacyclononane, known as "TACN" which is pronounced "tack-en," is a cyclic organic compound with the formula C6H123. TACN is derived, formally speaking, from cyclononane by replacing three equidistant CH2 groups with NH groups. TACN is one of the oligomers derived from aziridine, C2H4NH. Other members of the series include piperazine, C4H82, and the cyclic tetramer 1,4,7,10-tetraazacyclododecane.

Synthesis

The ligand is prepared from diethylene triamine as follows by macrocyclization using ethyleneglycol ditosylate.

Coordination chemistry

TACN is a popular tridentate ligand. It is threefold symmetric and binds to one face of an octahedron of metalloids and transition metals. The M unit is kinetically inert, allowing further synthetic transformations on the other coordination sites. A bulky analogue of TACN, is the N,N',N"-trimethylated analogue trimethyltriazacyclononane.

Illustrative complexes