Hydridoiridium(III) sulfoxide complexes and their reactivity toward dioxygen

Abstract

, and PAL KVINTOVICS. Can. J. Chem. 64, 897 (1986). Synthetic routes to hydridoiridium(II1) dimethylsulfoxide complexes via oxidative addition of HCl or Hz to precursor in situ iridium(1) species are described. The complexes, tran~,mer-IrHCl~(DMSO)~ (la) and ci~,rner-IrH~Cl(DMSO)~ (2), have been characterized by 'H nrnr and ir, and contain only S-bonded sulphoxide, DMSO. Comparison is made with data for other isomers reported in the literature, and some discrepancies are discussed. The decomposition of l a and 2 in chloroform leads to isomers of IIC~~(DMSO)~, while (2) with HCl generates C~~,C~~-I~HC~~(DMSO)~(DMSO) with the 0-bonded sulfoxide trans to hydride. The reaction of l a in dichloromethane with dioxygen occurs with a 1 : 1 stoichiometry and generates two complexes tentatively formulated as Ir(OH)CIZ(DMS0)2H20 (3) and IrC12(02)(DMS0)2~DMS0 (4); a hydroperoxide intermediate (Ir-OOH) initially formed from l a is considered to react with further l a in the rate-determining step. Oxidation of coordinated DMSO to the sulphone is not observed, implying that such a catalyzed 02-oxidation reported earlier in aqueous 2-propanol proceeds via reaction of IrOOH with free DMSO, or else via free hydrogen peroxide. BRIAN R. JAMES, ROBERT H. MORRIS, et PAL KVINTOVICS. Can. J. hem. 64, 897 (1986).On dtcrit des voies de syntheses de complexes de l'hydroiridium(III) et du dimtthylsulfoxyde qui impliquent l'addition de HCl ou de Hz a des prtcurseurs d'iridium(1) prtpar6s in situ. On a caracttrist les complexes, soit le IrHC12(DMS0)3-trans,mer (la) et le IrHC12(DMS0)3-cis,mer (2), en faisant appel a la rmn du 'H et a la spectroscopic ir et ils ne contiennent que des sulfoxydes lits par le soufre, DMSO. On fait une comparaison avec les donntes publites anttrieurement pour d'autres complexes et on discute des divergences. La dtcomposition des composes l a et 2 dans le chloroforme conduit ?ides isomtres du IrC13(DMS0)3 alors que la rtaction du compost 2 avec du HCl conduit a la formation de IrHC12(DMS0)2(DMS0)-cis,cis dans lequel le sulfoxyde est lit par I'oxygkne en position trans par rapport a l'hydrure. Dans le dichloromtthane, le compos6 l a rtagit avec le dioxygkne avec une sto'ichiomttrie 1:l et conduit 21 deux complexes auxquels on a attribut, ?i titre d'essai, les formules Ir(OH)C12(DMS0)2H20 (3) et IrC12(02)(DMS0)2.DMS0 (4); on a considere qu'un intermtdiaire hydroperoxyde (Ir-OOH) qui se forme initialement ?i partir de l a reagirait 2 1 nouveau avec le compost l a dans I'ttape dtterminante. On n'a pas observt d'oxydation du DMSO coordonnt en sulfone; ce rtsultat implique qu'une telle reaction catalyste d'oxydation par 0 2 , dont on a anttrieurement suggtrt I'existence pour des rtactions dans le propanol-2 aqueux, se produirait soit par une rtaction du W O H avec du DMSO libre soit via du peroxyde d'hydrogkne libre.[Traduit par la revue]

Synthesis and Reactivity of Ru-, Os-, Rh-, and Ir-Halide−Sulfoxide Complexes

“…405 Later, James and co-workers reported that the decomposition of trans-IrCl 2 H-(dmso-S) 3 in chloroform led to a mixture of the two linkage isomers mer-IrCl 3 (dmso-S) 3 (53) and mer,cisIrCl 3 (dmso-S) 2 (dmso-O) (54) (Chart 33), while decomposition of the dihydride cis,mer-IrH 2 Cl(dmso-S) 3 led to 53 exclusively. 406 It should be noted, though, that these neutral species were not isolated, but identified only in solution by NMR spectroscopy. 406 A neutral Ir(III)-dmso species containing metalated benzylacetophenone, cis,cis-IrCl 2 (dmso-S) 2 (PhCO-(CH 2 )CHPh), was isolated in small amounts during the hydrogenation of benzylideneacetophenone by propan-2-ol catalyzed by 51 and was structurally characterized by X-ray diffraction.…”

“…406 It should be noted, though, that these neutral species were not isolated, but identified only in solution by NMR spectroscopy. 406 A neutral Ir(III)-dmso species containing metalated benzylacetophenone, cis,cis-IrCl 2 (dmso-S) 2 (PhCO-(CH 2 )CHPh), was isolated in small amounts during the hydrogenation of benzylideneacetophenone by propan-2-ol catalyzed by 51 and was structurally characterized by X-ray diffraction. 409 The group of Milstein has recently reported the preparation of two novel Ir(I)-dmso complexes, IrCl-(dmso-S) 3 (55) led to the isolation of the chloro-bridged dimer [(dmso-S) 2 Ir(µ-Cl) 2 Ir(dmso-S) 2 ] (57).…”

Reactivity of electrophilic Cp*Ru(NO) complex towards alcohols

“…NMR spectrum for the reaction between 1 and 2-propanol in CDCl3 (verified by passing gaseous H2 through the same sample). Additionally, the formation of trace amounts of CHDCl2 was detected in CDCl3 solutions as a characteristic pattern of three lines of equal intensity centered at δ 5.33, resulting from the spin-spin coupling between proton and deuterium nuclei.The genesis of H2 and CHDCl 2 under these conditions could be ascribed to the formation of a short-lived metal hydride species[26]. The effect of deuterium substitution in the alcohol molecule was investigated to determine the source of the transferred hydrogen atom, through comparison of the reaction rates of 1 with 2-propanol vs (CD 3 ) 2 CD-OD[27].…”

Ir(I)/HCl Catalyzed Head-to-Tail Homocoupling Reactions of Vinylsilanes

“…On the basis of the results presented above, we proposed the mechanism displayed in Scheme for the vinylsilane homocoupling reaction . Initially, cyclooctene in the iridium(I) complex 2 undergoes exchange with vinylsilane to generate the corresponding vinylsilane-coordinated iridium(I) complex 5 , which then is protonated by HCl to produce the β-silylethyliridium(III) complex 7 via the intermediacy of hydridoiridium(III) complex 6 . The silylethyl group in 7 undergoes migratory insertion into the vinylsilane ligand through a carbometallation process to give 2,4-disilylbutyliridium(III) complex 8 .…”

“…Polymer 13a ( n = 2) was degraded by using perfluoro-hexyl iodide/BEt 3 -promoted iodine atom transfer radical addition followed by atom transfer cleavage with BEt 3 /H 3 PO 2 /pyridine as described above (Scheme a). This reaction leads to selective carbon–silicon bond cleavage to give α-perfluoroalkyl ketone 14 and the unstable silanol 15 , which dimerizes to form siloxane 16 .…”