Portal de Periódicos da CAPES

Reactions of the complexes M(Pr3)2(CO)3 (M = Cr, Mo, W; R =iPr, Cy) with thiols, hydrogen sulfide, disulfides, hydrogen iodide and iodine. The role of heteroatoms in determining the metal hydrogen bond strength at a sterically crowded metal center

1997; Elsevier BV; Volume: 259; Issue: 1-2 Linguagem: Inglês

10.1016/s0020-1693(97)05510-2

1873-3255

Russel F. Lang, Telvin D. Ju, G. Kiss, Carl D. Hoff, Jeffrey C. Bryan, Gregory J. Kubas,

CO2 Reduction Techniques and Catalysts

The complexes M(PCy3)2(CO)3 (M = Cr, Mo, W) react with phenyl disulfide to form stable 17-electron radical complexes Ṁ(PCy3)2(CO)3(SPh). Reaction with other alkyl and aryl disuufides also yields stable radicals and reaction with I2 yields Ẇ(P1Pr3)2(CO)3(I). Reaction with thiols, hydrogen sulfide and hydrogen iodide yield the corresponding 18-clectron hydrides W(P1Pr3)2(CO)3(H)(X). The crystal structure of W(P1Pr3)2(CO)3(H)(I) is reported and allows comparison with the structure of the radical complex Ẇ(P1Pr3)2(CO)3(I). The WH bond strengths in these heteroatorn complexes are low, 55–57 kcal mol−1. In spite of steric crowding, H atom transfer from W(P1Pr3)2(CO)3(H)(SPh) to Ċr(CO)2(PPh3)Cp occurs readily due to the stronger nature of the CrH bond formed. The chromium radical does not appear to attack the molecular hydrogen complex W(Pr3)2(CO)3(H2) or its dihydride form W(Pr3)2(CO)n3(H)2 based on rate of hydrogenation studies. Phenyl disulfide does react with either W(Pr3)2(CO)3(H2) a its dihydride tautomer W(Pr3)2(CO)3(H)2 to form thiophenol and W(Pr3)2(CO)3(SPḣ). This reaction is proposed to proceed by reaction of ṠPh radicals which are generated in situ. These studies are used to bracket the first WH bond dissociation energy in W(Pr3)2(CO)3(H)2. Additional studies of H atom and heteoratom transfer are described.