AMINO ACID AMIDES OF DITHIOOXALIC ACID: SPECTROSCOPIC, ELECTROCHEMICAL, AND MAGNETIC PROPERTIES OF COPPER(II) BINUCLEAR COMPLEXES AND CRYSTAL STRUCTURE OF (N,N′-(1,2-DITHIOXOETHANE-1,2-DIYL)BIS(METHYL METHIONINATO))BIS(BROMOCOPPER(II)