SYNTHESIS AND CHARACTERIZATION OF BIS(5,6-DIHYDRO-1,4-DITHIIN-2,3-DITHIOLATO) NICKEL(II), NICKEL(III) AND OF RELATED DIALKYL NICKEL(II) DITHIOLENE COMPLEXES

The reaction between Ni(II) and sodium salt of 5,6-dihydro-1,4-dithiin -2,3-dithiolate (DDDT2-) in the presence of oxygen results in the form ation of Ni(III) species, Ni(DDDT)(2-), which is isolated as tetraalky lammonium salt. The same reaction performed in the absence of oxygen y ields dianionic Ni(II) species, Ni(DDDT)(2)(2-), which is also isolate d as the tetraethylammonium salt. The bis(5,6-dihydro-1,4-dithiin-2,3- dithiolato) nickelate (II) dianion, Ni(DDDT)(2)(2-), reacts with methy l iodide to yield unusually stable bis(methylthio)dithiolene complex, Ni(CH3)(2)C8H8S8. All the isolated dithiolato-nickel(II) and nickel(II I) complexes are characterized by H-1 NMR, UV/Vis, IR and mass spectro scopic methods. The internal redox reaction of the nickel(II)-dithiola te has been studied by spectro-electrochemical method and the results were compared with those of other metal-dithiolenes. The alkylated nic kel(dithiolene) complex presumably undergoes cis-trans isomerization r eaction in solution, judging from the experimental results of variable -temperature H-1 NMR measurements.