ELECTRON ORGANOMETALLIC CLUSTERS .47. SYNTHESIS, CHARACTERIZATION, AND REACTIVITY TOWARD ELECTROPHILES/OXIDANTS OF H2RU3(RC(2)R')(CO)(6)(PPH(3))3 AND CRYSTAL STRUCTURES OF (MU-H)(2)RU-3(MU(3)-ETA(2)-ETCCET)(CO)(7)(PPH(3))(2) AND (MU-H)(2)RU-3(MU(3)-E

摘要

Electrochemical and chemical oxidations of 48-electron clusters (mu-H)(2)Ru-3(RCCR')(CO)(6-)(PPh(3))(3) (RCCR' = EtCCEt, HCCOEt, PhCCPh) give unstable radical cations. The radical cation derived from (mu-H)(2)Ru-3(EtCCEt)(CO)(6)(PPh(3))(3) decomposes in the presence of halide sources primarily by disproportionation to [(mu-H)(2)Ru-3(mu-X)(EtCCEt)(CO)(6)(PPh(3))(3)](+) (X = F, Cl). Electrophilic additions using Cl-2, I-2, and CF3CO2H give the analogous [(mu-H)(2)Ru-3(mu-X)-(EtCCEt)(CO)(6)(PPh(3))(3)](+) (X = Cl, I, H). Although the 48-/46-electron couple [Fe-3(RCCR)-(CO)(9)](2-)/Fe-3(RCCR)(CO)(9) is well-documented, and the 46-electron cluster [H2Ru3(HC(2)CMe(3))-(CO)(9-n)(PPh(3))(n)](2+) has been reported to be stable, there is no evidence for formation of 46-electron [H2Ru3(RCCR')(CO)(6)(PPh(3))(3)](2+) by two-electron oxidation of (mu-H)(2)Ru-3(RCCR')(CO)(6-)(PPh(3))(3). Two crystal structures are reported. For the diphosphine derivative (mu-H)(2)Ru-3-(EtCCEt)(CO)(7)(PPh(3))(2), the single Ru(1)-Ru(3) bond length is 2.757(2) Angstrom while the hydrido-bridged distances are Ru(1)-Ru(2) = 2.889(2) Angstrom and Ru(2)-Ru(3) = 2.993(2) Angstrom. The EtCCEt ligand is sigma-bonded to Ru(2) and Ru(3) (Ru(2)-C(2) = 2.118(8) Angstrom and Ru(3)-C(1) = 2.123(8) Angstrom) and pi-bonded to Ru(1) Ru(1)-C(1) = 2.338(7) Angstrom and Ru(1)-C(2) = 2.295(9) Angstrom. One PPh(3) ligand occupies an equatorial site on Ru(1); the second occupies an axial site on Ru(2), trans to the Ru(2)-alkyne sigma-bond. The single Ru(1)-Ru(3) bond length for (mu-H)(2)Ru-3- (EtCCEt)(CO)(6)(PPh(3))(3) . 3CH(2)Cl(2) is 2.744(1) Angstrom while the hydride-bridged distances are Ru(1)-Ru(2) = 2.891(1) Angstrom and Ru(2)-Ru(3) = 3.077(1) Angstrom. The EtCCEt ligand is bonded in the same 2 sigma,pi-manner as for the previous structure. Two PPh(3) ligands occupy those same two sites as in the diphosphine complex (equatorial on Ru(1), axial on Ru(2)), while the third occupies a close-to-equatorial site on Ru(3). Hydride ligands were located and refined in each structural study. [References: 48]