The cis/trans-isomerism on cobalt(III) complexes with 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid)

Abstract

The X-ray structure determinations show that 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic) acid H4L forms both cis- and trans-O,O isomeric complexes with Co(III). Orientation of the other donor atoms indicates the formation of cis-O1,O2-trans-N1,N8-cis-O1,N4-[Co(HL)].

The kinetically preferred cis-isomer is easily formed due to the strong hydrogen bond between the neighboring phosphonic acid groups.

Keywords

• cis/trans-isomerism
• cobalt(III) complexes
• methylphosphonic acid