CIRCULAR-DICHROISM AND C-13 NUCLEAR MAGNETIC-RESONANCE STUDIES OF SOME PHENYL-SUBSTITUTED ETHYLENEDIAMINE-N,N,N',N'-TETRAACETATE ANALOGS

The cobalt(III) complexes containing the I-stilbenediamine-N, N, N', N'-tetraacetate ion, [Co(l-sdta)]-, and the xylylenediamine-N, N, N', N'-tetraacetate ion, [Co(xdta)]-, have been synthesized and characterized by circular dichroism and carbon-13 nuclear magnetic resonance spectroscopy. Both complexes are analogues of [Co(edta)]- (edta=ethylenediamine-N, N, N', N'-tetraacetate ion). The complex [Co(l-sdta)]- contains a benzene ring bonded to each carbon of the ethylenediamine backbone, producing two asymmetric centers. The formation of the complex is stereoselective, yielding only one optical isomer. The complex [Co(xdta)]- has a benzene ring incorporated into the ethylenediamine backbone, producing a seven-membered ring when coordinated. Although studies indicated that the complex may be somewhat labile, resolution by fractional recrystallization after diastereoisomer formation was successful. The absorption, circular dichroism, 1H NMR, and 13C NMR spectra are reported and compared to those of other cobalt(III) sexidentate complexes. The phenyl groups appear to be the cause of some unusual behavior. © 1979, American Chemical Society. All rights reserved.