[CR(TREN(IMPY)(3))](CLO4)(3), WHERE TREN(IMPY)(3)=N[CH2CH2N=C(H)(PY)](3)

The structure of tris[4-(2-pyridyl)-3-aza-3-butenyl]-amine}chromium tr iperchlorate, [Cr{tren(impy)(3)}]-(ClO4)(3), [Cr(C24H27N7)](ClO4)(3), where tren(impy)(3) is N[CH2CH2N=C(H)(py)](3), consists of [Cr{tren-(i mpy)(3)}](3+) cations in which the Cr-III centre adopts distorted octa hedral coordination geometry. The trigonal twist angle of 52 degrees i s close to that expected for octahedral Cr-III and there is little evi dence suggesting coordination of the apical N atom of the tris(2-amino ethyl)-amine backbone of the ligand.