Oxidation of diphosphazane-bridged derivatives of diruthenium nonacarbonyl by silver(I) salts in protic solvents: synthesis, structural characterization and protonation of the adduct [Ru2{µ-η2-OC(O)}(CO)4{µ-(RO)2PN(Et)P(OR)2}2](R = Me or Pri) involving a novel mode of co-ordination of carbon dioxide
摘要:
Treatment of [Ru2(mu-CO)(CO),{mu-(RO)2PN(Et)P(OR)2)2] (R = Me or Pr(i)) with AgSbF6 in methanol, ethanol or tetrahydrofuran-water resulted in the formation of the solvento species [Ru2(CO)5(R'OH){mu-(RO)2PN(Et)P(OR)2}2] [SbF6]2 which is isolable for R' = H but which spontaneously deprotonatesto the alkoxycarbonyl-bridged derivative [Ru2{mu-eta2-OC(OR')}(CO)4{mu-(RO)2PN(Et)P(OR)2}2]SbF6 for R' = Me or Et. The aqua species [Ru2(CO)5(H2O){mu-(RO)2PN(Et)P(OR)2}2] [SbF6], was readily deprotonated in consecutive steps by appropriate bases to afford respectively the hydroxycarbonyl-bridged species [Ru2{mu-eta2-OC(OH)}(CO)4{p-(RO)2PN(Et)P(OR)2}2]SbF6 and the adduct [Ru2{mu-eta2-OC(O)}(CO)4{mu-(RO)2PN(Et)P(OR)2}2] in which the carbon dioxide molecule adopts a novel bridging co-ordination mode; this deprotonation is reversible and treatment of the latter with HBF4.OEt2 leads to stepwise regeneration of the aqua species. The co-ordinated water molecule in [Ru2(CO)5(H2O){mu-(PriO)2PN(Et)P(OPri)2)2] [SbF6]2 was readily displaced by acids HA derived from conjugate bases with potential co-ordinating properties such as thiolate ions R''S- (R'' = H or Ph) or carboxylate ions R'''CO2- (R''' = H, Me, Ph or CF3), to produce monocationic pentacarbonyl species of the type [Ru2A(CO)5{mu-(PriO)2PN(Et)P(OPri)2)2]SbF6, detection of an intermediate, presumably [RU2(CO)5-(HA){mu-(PriO)2PN(Et)P(OPri)2}2] [SbF6]2, was possible for HA = HCO2H and MeCO2H. The sulfido derivatives [RU2(SR'')(CO)5{mu-(PriO)2PN(Et)P(OPri)2}2]SbF6 (R'' = H or Ph) rapidly decarbonylate in solution to afford the tetracarbonyl products [RU2(mu-SR'')(CO)4{mu-(PriO) 2PN(Et)P(OPri)2}2]SbF6 in which the sulfido group bridges the two ruthenium atoms. On the other hand the carboxylato derivatives [Ru2{OC(O)R'''}(CO)5{mu-(PriO)2PN(Et)P(OPri)2}2]SbF6 (R''' = H, Me, Ph or CF3) are stable to decarbonylation in solution at room or elevated temperatures but can be decarbonylated to the carboxylato-bridged products [Ru2{mu-eta2-OC(R''')O}(CO)4{mu-(PriO)2PN(Et)P(OPri)2}2]SbF6 by irradiation with ultraviolet light. The water molecule in [Ru2(CO)5(H2O){mu-(PriO)2PN(Et)P(OPri)2}2]-[SbF6]2 was also readily displaced by the conjugate bases of the above acids HA, but in contrast to that observed for the carboxylic acids R'''CO2H (R''' = H, Me or Ph), reaction of the aqua species with the corresponding carboxylate ions R'''CO2- led to direct formation of the carboxylato-bridged species [Ru2{mu-eta2-OC(R''')O}(CO)4(mu-(PriO)2PN(Et)P(OPri)2}2]SbF6. Possible mechanisms for the formation of the various products are discussed as are the structures of [Ru2(CO)5(H2O){mu-(PriO)2PN(Et)P(OPri)2}2][SbF6]2.OCMe2, [RU2{mu-eta2-OC(OEt)}(CO)4{mu-(MeO)2PN(Et)P(OMe)2}2]SbF6, [Ru2{mu-eta2-OC(Me)O}(CO)4{mu-(PriO)2PN(Et)P(OPri)2}2]PF6 and [RU2{mu-eta2-OC(O)}(CO)4{mu-(PriO)2-PN(Et)P(OPri)2}2], established X-ray crystallographically.
Oxidation behaviour of the unsaturated diruthenium species [Ru<sub>2</sub>(µ<sub>sb</sub>-CO)<sub>2</sub>(CO)<sub>2</sub>{µ-(Pr<sup>i</sup>O)<sub>2</sub>PNEtP(OPr<sup>i</sup>)<sub>2</sub>}<sub>2</sub>]
作者:John S. Field、Raymond J. Haines、Mark W. Stewart、Stephen F. Woollam
DOI:10.1039/dt9960001031
日期:——
Treatment of the formally unsaturated species [Ru-2(mu(sb)-CO)(2)(CO)(2)(mu-etipdp)(2)][sb = semi-bridging, etipdp = ((PrO)-O-i)(2)PNEtP(OPri)(2)] with silver (1) salts such as AgSbF6 or AgBF4 In MeCN or PhCN led directly to the formation of the disolvated species [Ru-2(CO)(4)(RCN)(2)(mu-etipdp)(2)]X(2) (R = Me or Ph; X = SbF6 or BF4), with no intermediates being detected. In contrast, as established spectroscopically, oxidation of this complex with silver(I) salts-in very weakly co-ordinating solvents such as acetone or methanol afforded silver adducts of the parent species. Also, reaction with the electron acceptor tcnq (7,7,8,8-tetracyano-p-quinodimethane) in tetrahydrofuran (thf) gave the electron-transfer salt [Ru-2(eta(1)-tcnq)(CO)(4)(thf)(mu-etipdp)(2)][tcnq], while with p-chloranil (tetrachloro-1,4-benzoquinone) produced [Ru-2(mu-Cl)(CO)(4)(mu-etipdp)(2)][p-OC6Cl4O](2) as a consequence of the benzoquinone functioning as a chlorinating agent as well as an electron acceptor. Cyclic voltammograms of [Ru-2(mu(sb)-CO)(2)(CO)(2)(mu etipdp)(2)] and [Ru-2(CO)(4)(RCN)(2)(mu-etipdp)(2)][SbF6](2) (R = Me or Ph) have been measured in both aceto- and benzo-nitrile and are readily interpreted in terms of the redox process [Ru-2(mu(sb)-CO)(2)(CO)(2)(mu-etipdp)(2)] + 2RCN (2e)reversible arrow(-2e) [Ru-2(CO)(4)(RCN)(2)(mu-etipdp)(2)](2+). The structure of the acetonitrile species [Ru-2(CO)(4)(MeCN)(2)(mu-etipdp)(2)][BF4](2) . CH2Cl2 has been determined X-ray crystallographically.