SYNTHESIS, NMR SPECTROSCOPIC INVESTIGATION, AND CRYSTAL-STRUCTURES OF 1,3-DIHYDRO-2-LAMBDA-4-BENZOTELLUROLE-2,2-DIYL BIS(DIETHYLDITHIOCARBAMATE), C8H8TE[S2CNET2]2 - S,S'-1,3-DIHYDRO-2-LAMBDA-4-BENZOTELLUROLE-2,2-DIYL O,O,O',O'-TETRAETHYL BIS(DITHIOPHOSPHATE), C8H8TE[S2P(OET)2]2 - AND 1,3-DIHYDRO-2-LAMBDA-4-BENZOTELLUROLE-2,2-DIYL BIS(O-ETHYL XANTHATE), C8H8TE[S2COET]2E