Cobalt(III) complexes of 3,7-dithianonane-1,9-diamine
Abstract
A convenient synthetic route to the ligand 3,7-dithianonane-1,9-diamine (dtnd) has been developed. A series of cobalt(III) complexes, [Co(dtnd)Cl2]+, [Co(dtnd)O3C]+, [Co(dtnd)(NO2)2]+, [Co(dtnd)(NO2)Cl]+, [Co(dtnd)-(NO2)Br]+, [Co(dtnd)(ox)]+(ox = oxalate), with a variety of anions have been prepared and characterised. The cis-complexes have the cis-β-configuration in contrast to the complexes of 3,6-dithiaoctane-1,8-diamine (dtod) which give only the cis-α-isomers. In the case of [Co(dtnd)Cl2]+, both the cis-β- and the trans-isomers can be prepared. In the complex [Co(dtnd)(NO2)2]+, one nitro-group is readily replaced by Cl– or Br– on treatment with the appropriate mineral acid. A recent crystal-structure determination on the complex [Co(dtnd)(NO2)Cl]Cl has shown that the nitro-group trans to the sulphur atom is displaced. The complex has the cis-β-configuration with the six-membered chelate ring in the chair conformation. The sulphur centres have the same chirality. N.m.r., i.r., and electronic spectra of the complexes are discussed.