Multinuclear NMR and crystallographic studies of triorganotin valproates and their in vitro antifungal activities

• Complexes [{SnR3(OVp)}n], R = Me (1), Bu (2) and Ph (3) have been prepared.
• Complexes (1) and (3) have been structurally authenticated.
• Complexes (1)–(3) have been studied by solution- and solid-state 119Sn NMR.
• The biocide activity of (1)–(3) have been screened.

The reactions of triorganotin chlorides and sodium valproate, Na(OVp), yielded three triorganotin valproates [{SnMe3(OVp)}n] (1), [{SnBu3(OVp)}n] (2) and [SnPh3(OVp)] (3). All complexes have been authenticated in terms of infrared, 1H and 13C NMR, and solution- and solid-state 119Sn NMR, 119Sn Mössbauer and X-ray crystallography. The 119Sn NMR experiments provided important informations concerning the structures of (1)–(3) in solution and in the solid state. The X-ray experiments revealed the double-polymeric chain of complex (1), in which the geometry at the Sn(IV) is trigonal bipyramidal with intermolecular valproate bridges. The structure of complex (3) was re-determined and the new data show the tin cation at the centre of a distorted trigonal bipyramid, and not coordinated by four electron donating groups. The biological activity of all derivatives has been screened in terms of IC50 (μmol L−1) against C. albicans (ATCC 18804), C. tropicalis (ATCC 750), C. glabrata (ATCC 90030), C. parapsilosis (ATCC 22019), C. lusitaniae (CBS 6936) and C. dubliniensis (clinical isolate 28). Complex (3) exhibited the best biocide activity.