Multiple Bonds between Main-Group Elements and Transition Metals. 67. Synthesis of Novel Half-Sandwich Rhenium(V) Complexes of Mono- and Bidentate Sulfur-Containing Ligands: X-ray Crystal Structure of the Xanthate-S,S Complex (ή⁵-C₅Me₅)ReCl₃(S₂CO-c-C₆H₁₁)

The d² rhenium(V) complex (ή⁶-C₆Meg)Re(0)Cl₂ (1) reacts with thiolates under ambient conditions to yield the disubstituted complexes 2 of composition (ή-C₅Me₅)Re(0)(SR¹)₂ [R¹= ethyl (2a), phenyl (2c), 2-pyridyl (2d)]. Bulkier ligands such as 2-methylpropane-2-thiolate give rise to formation of monosubstituted complexes, e.g., (ή⁵-C₅Me₅)Re(0)(Cl)(S-t-C4H₉) (3) at room temperature, while disubstitution occurs in refluxing toluene with formation of compound 2b (R¹= τ-C₄H₉). The reactions of (ή⁶-C₅Meg)ReCl₄(4) with sodium cyclohexylxanthate or with lithium Nβ-diethyldithiocarbamate yield monosubstituted derivatives of formula (ή-C₅Me₅ReCl₃CR²) (5a,b). A single-crystal X-ray diffraction study of the xanthate complex (Å⁵-C₅Me₅)ReCl₃(S₂CO-c-C₆H₁₁) (5a, R²= 0-c-C₆H_n) shows an octahedral coordination sphere around the rhenium, with the sulfur atoms of the bidentate ligand being bonded to the metal atom in an equatorial and in an axial position.