“…methylphosphonates) and their potential applications in the antisense strategy for the artificial control of gene expression has stimulated wide interest in this class of compounds (Englisch & Gauss, 1991;Miller, 1989). In contrast, only three solid-state structures of dinucleoside methylphosphonates are known to date, namely SpdAp(Me)T (Chacko, Lindner, Saenger & Miller, 1983), Rp-dCp(Me)G (Han et al, 1990) and SpTp(Me)sT (where sT is 4-thiothymidine) (Szab6, Norrus, Norrestam & Stawifiski, 1993).…”