novel hydrogen - phosphonodithioate compositions are provided which are particularly useful for forming internucleotide and internucleoside linkages in oligonucleosides or oligonucleotides . the oligonucleotides and analogs thereof made by using the hydrogen - phosphonodithioate compositions may be therapeutically useful as antiviral and anticancer agents and may have other therapeutic or diagnostic uses . a method for making the hydrogen - phosphonodithioates is provided as well as a method for converting same to an activated intermediate for substitution on the phosphorus atom .