Azido-amine-cobalt(III) complexes - Crystal structures of cis-[Co(tren)(N-3)(2)]ClO4 and trans-[Co(3,2,3-tet)(N-3)(2)]ClO4

The structures of the two complexes cis-[Co(tren)(N-3)(2)]ClO4 (I) and tran s-[Co(3,2,3-tet)(N-3)(2)]ClO4 (II) (tren=2,2',2 "-triaminotriethylamine; 3, 2,3-tet=1,10-diamino-4,7-diazadecane) have been determined by X-ray crystal lography. The compounds consist of isolated complex cations [Co(tren)(N-3)( 2)](+) and [Co(3,2,3-tet)(N-3)(2)](+) with distorted octahedral geometry an d ClO4- counter ions. The two single coordinated azido ligands are arranged cis and trans in the cations of I and II, respectively. The Co-N(azido) di stances vary from 1.946(3) to 1.964(3) Angstrom. The configurational geomet ry for these complexes were previously reported based on the position of th e asymmetric stretching mode of vibration of the coordinated azido ligands, nu a(N-3) in the 2000-2065 cm(-1) region. The results of X-ray studies are consistent with the previous assigned geometry based on the IR of nu a(N-3 ) and strongly support its use as a valuable tool for elucidating the geome trical isomerism in octahedral diazido metal complexes. (C) 1999 Elsevier S cience Ltd. All rights reserved.