The monosodium salt of trithiocyanuric acid, C3N3S3H2Na, has been isolated as its trihydrate (1) by partial neutralisation of C3N3S3H3 with NaOH. Each sodium in the structure displays a novel cis-S2NaO4 coordination sphere and is hydrogen bonded to the anion, which adopts its thione form. Compound 1 has been used to synthesise other unsymmetrically-metallated trithiocyanuric acid derivatives. typified by [C3N3S3H2Cu(PPh3)(2)] and whose structure has also been determined. The nickel complex [C3N3S3H2NiCl(PPh3)(2)] (.) 0.5CH(2)Cl(2) was also obtained, but only tri-substituted compounds C3N3S3[Au(PPh3)](3) (.) 2CH(2)Cl(2) and C3N3S3(SnMe3)(3) were formed when 1 was reacted with (Ph3P)AuCl and Me3SnCl, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.