Syntheses and Crystal Structures of Tungsten Complexes with Various Ligands Containing (1,3-Dithioliumyl)diphenylphosphine

The (dithioalkylcarbonyl)diphenylphosphinotungsten complexes W(CO)5[PPh2(CS2R)] (2−5) (R = CH2C⋮CH; CH2C⋮CD; CH2C⋮N; CH(CH3)C⋮N) are accessible by the alkylation reactions of the complex [Et4N][W(CO)5PPh2CS2] (1) with unsaturated organic halides. Protonation of 2−5 with HBF4 at room temperature causes intramolecular cyclization to form the cationic complexes (6−9) (R, R‘ = H, CH3; H, CH2D; H, NH2; CH3, NH2). The complex (10) is produced by the reaction of 4 or 8 with Ph3CBF4. In complexes 6−10, proton-induced intramolecular cyclization was followed by an unprecedented 1,3-hydrogen shift, forming five-membered cationic 1,3-dithiolium rings. The 1,3-hydrogen shift process did not occur in similar organic compound but in this metal-assisted system. The mechanism was confirmed both by the reactions of 4 with Ph3CBF4 and by deuterium-labeling experiments. The protonation reaction of 2 to 6 is not reversible, but deprotonation of 8 by n-BuLi or PPh3 gives 4 quantitatively. Treatment of 8 with n-Bu4NF yielded co...