Osmium(IV) Halide Complexes with Dimethyl Sulfoxide[H(dmso) 2 ][OsX 5 (dmso‐κ O )], X=Cl, Br: Synthesis, Structure, and Properties

Two osmium complexes of common formula [H(dmso) 2 ][Os IV Х 5 (dmso‐κ O )] 1 (Х=Cl) and 2 (Х=Br) are synthesized via the reaction of H 2 OsX 6 (Х=Cl, Br) with DMSO. The complex 1 crystallized in the orthorhombic space group Pca2 1 . For 2 , two orthorhombic polymorphs are found, namely, 2 a in space group Cmcm and 2 b in space group Pbca . Within the [H(dmso) 2 ] + cations of 1 and 2 a , the cis ‐configuration of the DMSO moieties has been observed for the first time. The complexes are characterized by a set of spectroscopic (NMR, IR, UV‐Vis, EXAFS/XANES) and diffraction (single crystal and powder) techniques. Both complexes 1 and 2 retain their molecular structures in DMSO and acetone solutions, as evidenced by Os L 3 ‐edge EXAFS/XANES. 1 H NMR spectra of 1 and 2 in DMSO solutions reveal signals of coordinated DMSO. In acetone solutions, signals of the [H(dmso) 2 ] + cations are observed in addition to those of coordinated neutral DMSO.