Synthesis of 9-substituted-8, 9 10, 11-tetrahydro-7H-7, 11-diaza-9k5 -phosphacycloocta [d,e] naphthalene-9-sulfides/selenides (4–13) was accomplished in three steps. 1,8-diamino naphthalene (2) was reacted with tris (bromomethyl) phosphine (1) in the presence of triethylamine in dry tetrahydrofuran (THF) under N2 atmosphere to form the corresponding intermediate (3). It was converted to the corresponding sulfide (4) and selenide (5) by the reaction with sulfur and selenium, respectively. The intermediates 4 and 5 were reacted with two achiral alcohols and two achiral amines to obtain the title compounds (6–13). The structures of the title compounds were established by elemental analysis and spectral data (IR, 1 H, 13C, 31P NMR, and FAB mass). The antimicrobial activity of these compounds was evaluated and they exhibited significant activity.