91311-62-5Relevant articles and documents
Protonation and hydrogenation of triosmium clusters containing the bridging diphosphine ligands Ph2P(CH2)nPPh2 (n=1 to 4)
Deeming, Antony J.,Kabir, Shariff E.
, p. 359 - 366 (1988)
Members of the series of bridging diphosphine clusters where diphos=Ph2P(CH2)nPPh2 show interesting differences in their reactivity towards H+ and H2.Protonation leads to
The Preparation of an Unsaturated Hydrido Osmium Cluster by Hydrogenolysis of a Cyclometallated Phosphine; the X-Ray Structure of
Clucas, Jennifer A.,Harding, Marjorie M.,Smith, Anthony K.
, p. 1280 - 1281 (1985)
Treatment of > with H2 affords a high yield of the unsaturated cluster which has been characterised by X-ray crystallography.
Ortho-metalation dynamics and ligand fluxionality in the conversion of Os3(CO)10(dppm) to HOs3(CO)8[μ- PhP(C6H4-μ2,ν1)CH 2PPh2]: Experimental and DFT evidence for the participation of agostic C-H and π-aryl intermediates at an intact triosmium cluster
Huang, Shih-Huang,Keith, Jason M.,Hall, Michael B.,Richmond, Michael G.
, p. 4041 - 4057 (2011/01/07)
The mechanism for the stepwise conversion of Os3(CO) 10(dppm) to HOs3(CO)9[μ-PhP(C 6H4)CH2PPh2] and HOs 3(CO)8[μ-PhP(C6H4- μ2,ν1)CH2PPh2] has been investigated. The octacarbonyl cluster HOs3(CO)8[μ- PhP(C6H4-μ2,ν1)CH 2PPh2] is in rapid equilibrium with the isomer containing a metalated phenyl ring that is bound to a single osmium, HOs 3(CO)8[μ-PhP(C6H4- ν1)CH2PPh2], which in turn captures CO to give HOs3(CO)9[μ-PhP(C6H4)CH 2PPh2] in a reaction that is first-order in cluster and CO with a rate constant of 23.9(3) × 10-3 M-1 s -1 at 288 K. The kinetics for the transformation of HOs 3(CO)9[μ-PhP(C6H4)CH 2PPh2] to Os3(CO)10(dppm) have been studied in toluene over the temperature range 317-340 K and found to be first-order in starting cluster and independent of CO. Important insight into the reductive coupling process was obtained from the carbonylation kinetics employing DOs3(CO)9[μ-(Ph-d2)P(C 6H3D)CH2PPh2-d4], which was prepared from Os3(CO)10(dppm-d8) and where all of the ortho sites on the aryl groups contained deuterium. Here, a significant inverse isotope effect (kH/kD = 0.50) was found, whose origin actually derives from an inverse equilibrium isotope effect, and this supports a preequilibrium phase of the reaction involving a hydride (deuteride) cluster and an intact Os3 cluster containing a coordinated aryl moiety, prior to the rate-limiting formation of the unsaturated cluster Os3(CO)9(dppm-Pa,Pe). Experimental proof for the intermediacy of an extremely labile cluster-aryl complex(es) in the proposed preequilibrium step has been demonstrated by photochemical experiments using the isotopically labeled cluster Os 3(CO)10(dppm-d4), where each aryl group contains one ortho hydrogen and deuterium atom. Photolysis of Os 3(CO)10(dppm-d4) in toluene-d8 gives a 70:30 mixture of the octa- and nonacarbonyl HOs3(CO) 8,9[μ-(Ph-d1)P(C6H3D)CH 2PPh2-d4] and DOs3(CO) 8,9[μ-(Ph-d1)P(C6H4)CH 2PPh2-d4], respectively, over the temperature range 243-298 K. These data indicate that the intermediates formed after CO loss are kinetically labile and that the ortho metalation leads to a thermodynamically equilibrated mixture of hydride and deuteride clusters. DFT calculations corroborate the experimental findings and provide crucial details on the nature and lability of those cluster species that do not lend themselves to direct spectroscopic observation.
Oxidative addition of silanes R3SiH to the unsaturated cluster [Os3(μ-H){μ3-Ph2PCH2PPh(C 6H4)}(CO)8]: Evidence for reversible silane formation in the dynamic behaviour of [Os3(μ-H)-(SiR 3)(CO)9(μ-dppm)]
Deeming, Antony J.,Hassan, Md. Manjur,Kabir, Shariff E.,Nordlander, Ebbe,Tocher, Derek A.
, p. 3709 - 3714 (2007/10/03)
Oxidative addition of the silanes R3SiH (R3 = Ph 3, Et3, EtMe2) to the unsaturated cluster [Os3(μ-H){μ3-Ph2PCH2PPh(C 6H4)}(CO)8] leads to the saturated clusters [Os3(μ-H)(SiR3)(CO)9(μ-dppm)] (SiR 3 = SiPh3 1, SiEt3 2 and SiEtMe2 3) and the unsaturated clusters [Os3(μ-H)2(SiR 3){μ3-Ph2PCH2PPh(C 6H4)}(CO)7] (SiR3 = SiPh3 4, SiEt3 5 and SiEtMe2 6). Structures are based on spectroscopic evidence and a XRD structure of [Os3(μ-H)(SiPh 3)(CO)9(μ-dppm)] 1 in which all non-CO ligands are coordinated equatorially and the hydride and the silyl groups are mutually cis. From variable-temperature 1H NMR spectra of the SiEt3 compound 2, exchange of the P nuclei is clearly apparent. Simultaneous migrations of the SiEt3 group and of the hydride from one Os-Os edge to another generate a time-averaged mirror plane in the molecule. VT 1H NMR spectra of the somewhat less bulky compound [Os 3(μ-H)(SiMe2Et)(CO)9(μ-dppm)] 3 have been analysed. Two isomers 3a and 3b are observed with the hydride ligand located on different Os-Os edges. Synchronous migration of the hydride and SiMe 2Et groups is faster than the observed interconversion of isomers which occurs by hydride migration alone. The synchronous motion of H and SiR3 only occurs when these ligands are mutually cis as in the major isomer 3a and we propose that this process requires the formation of a transient silane complex of the type [Os3(η2-HSiR 3)(CO)9(μ-dppm)]. Turnstile rotation within an Os(CO)3(η2-HSiR3) group leads to the observed exchange within the major isomer 3a without exchange with the minor isomer. This process is not observed for the minor isomer 3b because the hydride and the silyl group are mutually trans. Protonation to give [Os 3(μ-H)2(SiR3)(CO)9(μ-dppm)] + totally suppresses the dynamic behaviour because there are no edge vacancies.
