Five-coordinate fluorobenzothiolate osmium(IV) complexes [Os(SRF)4(PR3)] (RF = C6F4H-4, R3 = Ph2(C6F5); RF = C6F4H-4, R3 = (OPh)3; RF = C6F5, R3 = (OPh)3): Single-crystal structures and solution structural characterization

Reactions of OsO4 with excess of HSRF and PR3 in ethanol afford five-coordinate compounds [Os(SRF)4(PR3)] (RF = C6F4H-4, R3 = Ph2(C6F5) (1); RF = C6F4H-4, R3 = (OPh)3 (2); and RF = C6F5, R3 = (OPh)3 (3)). Single crystal X-ray diffraction studies of 1–3 exhibit a common pattern with an osmium center in a trigonal-bipyramidal coordination arrangement. Axial positions are occupied by mutually trans thiolate and phosphine or phosphite ligands, while the remaining three equatorial positions are occupied by thiolate ligands. In compound 1 the tetrafluorophenyl rings of the equatorial ligands are directed away from the axial phosphine ligand in a “3-up” arrangement. In contrast, a “2-up, 1-down” arrangement was found in compounds 2 and 3, where only two of the fluorinated rings from the equatorial thiolates are directed towards the axial thiolate, while the fluorinated substituent of the third equatorial thiolate is directed towards the phosphine ligand. Structural characterization in solution by 1H, 31P{1H} and 19F NMR, variable temperature and COSY 19F–19F NMR studies are discussed.

Graphical abstractOsO4 with excess of HSRF and PR3 afford the trigonal bipyramidal compounds [Os(SRF)4(PR3)] with the phosphorous-containing ligand in an axial position. Substituents of the equatorial thiolates exhibit “3-up” or “2-up, 1-down” arrangements both in solution and solid state. NMR studies establish that restricted rotations become fluxional as the temperature increases.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► OsO4 with excess of HSRF and PR3 afford trigonal bipyramidal compounds. ► Restricted rotations become fluxional as the temperature increases. ► “3-up” and “2-up, 1-down” arrangements are found clearly in solution and solid state. ► Fluorinated systems offer the possibility to distinguish the structural details.