Synthesis, characterization and X-ray structure of stannocanes substituted with a cyclic dithiophosphate ligand X(CH 2CH 2S) 2Sn nBu [S 2P(OCH 2C(Et 2)CH 2O)], (X=O, S): a study about the conformational tendencies and the relationship with the anomeric effect of the stannocane rings

Abstract

The preparation and conformational study of two stannocanes, 5- n-butyl-5-(5′,5′-diethyl-2′-thioxo-1′,3′,2′-dioxaphosphorinane-2′-thiolate)-1-oxa-4,6-dithia-5-stannocane, O(CH 2CH 2S) 2Sn n Bu[S 2P(OCH 2CEt 2CH 2O)] ( 1) and 2- n-butyl-5-(5′5′-diethyl-2′-thioxo-1′,3′,2′-dioxaphosphorinane-2-thiolate)-1,3,6-trithia-2-stannocane S(CH 2CH 2S) 2Sn n Bu[S 2P(OCH 2CEt 2CH 2O)] ( 2) is reported. These compounds were prepared from the corresponding chloro-oxa and -thia-stannocanes and the sodium salt of dithiophosphoric acid (2-mercapto-2-thiono-1,3,2-dioxaphosphorinane) in ethanol. Compounds 1 and 2 were characterized by IR, EI-MS and multinuclear NMR ( 1H, 13C, 31P). The molecular structures were determined by X-ray analyses. The eight-membered ring in both compounds has a boat–chair conformation with a 1,5 transannular Sn⋯O (2.468 Å), Sn⋯S (2.94 Å) interaction. The 1,3,2-dioxaphosphorinane ring in 1 and 2 present a chair conformation with the stannocane in the axial position, in accordance with the anomeric effect. The coordination of the Sn-atoms is trigonal-bipyramidal in 1 and intermediate between trigonal-bipyramidal and a bicapped tetrahedral arrangement in 2.