- Vibrational Couplings in Hydridocarbonyl Complexes: A 2D-IR Perspective
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Hydridocarbonyl complexes, a class of industrially relevant catalysts, contain both the M-H and M-CO moieties. Here, using two-dimensional infrared spectroscopy, we examine the coupling of the typically weak M-H stretching mode and the intense M(CO) mode. By studying a series of Ir(I)- and Ir(III)-based hydridocarbonyl complexes, we show that the arrangement of the H and CO ligands in a trans configuration leads to strong vibrational coupling and mode delocalization. In contrast, a cis arrangement leads to no coupling, with the localized M-H mode having a much larger anharmonicity. These results highlight a promising strategy for enhancing the M-H vibration by intensity borrowing from the strong CO modes in a trans configuration, allowing for direct determination by infrared spectroscopy of both the oxidation (by frequency shifts) and the protonation state (via vibrational coupling) of the complex, in mechanistic studies of proton-coupled electron transfer reactions.
- Fernández-Terán, Ricardo,Hamm, Peter,Ruf, Jeannette
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- Reaction of an (alkyl)(alkenyl)(alkynyl)iridium(III) complex with HCl: Intramolecular C-C bond formation from alkyl, alkenyl, and alkynyl groups coordinated to "Ir(CO)(PPh3)2". H/D exchange between CH3 and DCl
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Reaction of the (alkyl)(alkenyl)(alkynyl)iridium(III) complex [Ir(CH3)(CH=CHNEt3)(C≡ C(p-C6H4CH3))(CO)(PPh3) 2]ClO4 (3) with aqueous HCl initiates an intramolecular co
- Chin, Chong Shik,Cho, Haeyeon,Won, Gyongshik,Oh, Moonhyun,Ok, Kang Min
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p. 4810 - 4816
(2008/10/08)
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- Tetravalent tellurium ligands
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Oxidative addition of TeCl4 to Vaska's complex gave the trichlorotelluronium complex [IrCl2-(TeCl3)(CO)(PPh3)2] (structure depicted), which contains a rare example of a structurally characterized tetravalent tellurium ligand. The coordination at the Te(IV) center is - in full agreement with the VSEPR model - distorted trigonal bipyramidal.
- Dyson, Paul J.,Hill, Anthony F.,Hulkes, Alexander G.,White, Andrew J. P.,Williams, David J.
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p. 512 - 514
(2007/10/03)
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- New products in an old reaction: Isomeric products from H2 addition to Vaska's complex and its analogues
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para-Hydrogen enhanced NMR signals aid detection of minor isomers of complexes IrH2(L)2(CO)Cl (L = PPh3, PMe3, PPh2Cl and AsPh3) containing magnetically inequivalent hydride ligands that ar
- Hasnip, Sarah K.,Duckett, Simon B.,Sleigh, Christopher J.,Taylor, Diana R.,Barlow, Graham K.,Taylor, Mike J.
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p. 1717 - 1718
(2007/10/03)
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- Oxidative addition/decarbonylation of αω-alkanedioyl dichlorides. Metallacycle formation via intramolecular reductive cyclization of a pendant acid chloride with samarium(II) iodide
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Controlled oxidative addition and decarbonylation at one end of α,ω-alkanedioyl dichlorides is reported with (Ph3P)2Ir(N2)Cl, giving Ir(III) alkyl complexes bearing a pendant acid chloride functionality. The use of the dinitrogen complex enables suppression of competitive intramolecular lactonization processes. Use of 2 equiv of samarium(II) diiodide uniquely promotes intramolecular reductive cyclometalation of one of these complexes, forming a cyclic acyl complex. This cyclization is highly sensitive to both electronic factors in the substrate and the nature and stoichiometry of the reducing agent.
- Zizelman, Paul M.,Stryker, Jeffrey M.
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p. 1713 - 1715
(2008/10/08)
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- Reactions of iridium(I) alkoxide complexes with acyl and alkyl sources: Carbon-oxygen bond-forming reactions
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The reactions of alkoxyiridium complexes trans-ROIr(CO)(PPh3)2 (R = Me, Ph, t-Bu, i-Pr) with organic substrates R′X (R′ = Me, CH3C(O), C6H5C(O), C6H5CH2C(O), HC(O); X = Cl, I, H)
- Bernard, Karen A.,Atwood, Jim D.
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p. 795 - 800
(2008/10/08)
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- Selectivity in C-O bond formation: Reaction of acid chlorides and methyl iodide with trans-MeOIr(CO)(PPh3)2
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Reactions of RX (RX = MeI, CH3C(O)Cl, C6H5C(O)Cl, and C6H5CH2C(O)Cl) with trans-MeOIr(CO)(PPh3)2 have been examined. In each case, an adduct is formed, RIr(OMe)(CO)(PPh3)2X, which is stable for R = Me. For the acid chlorides, this adduct eliminates ester, forming Ir(CO)(PPh3)2Cl. Thus the carbon-oxygen bond leading to ester products is formed more readily than the carbon-oxygen bond leading to dimethyl ether.
- Bernard, Karen A.,Atwood, Jim D.
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p. 1133 - 1134
(2008/10/08)
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- FORMATION OF CARBON-CARBON BONDS ON DI(ORGANO)IRIDIUM COMPLEXES, RR'Ir(CO)(PPH3)2X (R,R' = Me, Ph, CH2Ph, C(O)CH3; X = Cl, I) AND THE CRYSTAL STRUCTURE OF cis,cis,trans-
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The reactions of RX with trans-R'Ir(CO)(PPh3)2 are reported.Addition of CH3C(O)Cl to trans-CH3Ir(CO)(PPh3)2 leads to acetone; addition of CH3I to trans-PhIr(CO)(PPh3)2 leads to toluene; and addition of CH3I to trans-C6H5CH2Ir(CO)(PPh3)2 leads to ethylbenzene.Reaction of C2H5Br with trans-CH3Ir(CO)(PPh3)2 leads to CH4 and C2H4.The addition of CH3I to trans-CH3Ir(CO)(PPh3)2 leads to Ir(CH3)2Ir(CO)(PPh3)2I from which Ir(CH3)2(CO)2(PPh3)2(1+) and Ir(CH3)2(CO)(PPh3)2(1+) can be prepared.These dimethyl complexes do not undergo reductive elimination of ethane, acetone or diacetyl under a variety of conditions (CH4 and C2H6 are formed at decomposition).Thus for these complexes the charge, the presence of a free coordination site and the cis stereochemistry do not facilitate reductive elimination reactions.To ascertain that no structural features were preventing reductive elimination from the dimethyl complex we have examined the structure of cis,cis,trans-.This crystallizes in the centrosymmetric triclinic space group P (C1i; No. 2) with a 11.708(2), b 11.738(2), c 14.702(2) Angstroem, α 87.544(13), β 79.181(14), γ 76.963(15)deg, V 1933.4(6) Angstroem3 and D(calc'd) 1.64 g cm-3 for mol. wt. 951.9 and Z = 2.X-ray diffraction data (Mo-Kα, 2θ 4.5-50.0deg) were collected with a Syntex P21 automated four-circle diffractometer and the structure was refined to R 3.5percent for all 6835 reflections (R 2.9percent for those 6133 reflections with F0 > 6?(F0)).The central d6 iridium(III) ion has a slightly distorted octahedral stereochemistry, with Ir-CO 1.943(5) and 1.956(5) Angstroem, Ir-CH3 2.152(5) and 2.155(5) Angstroem and Ir-PPh3 2.391(1) and 2.400(1) Angstroem; interligand angles include OC-Ir-CO 102.09(20), CH3-Ir-CH3 89.70(19) and PPh3-Ir-PPh3 174.68(4)deg.
- Churchill, Melvyn Rowen,Fettinger, James C.,Janik, Thomas S.,Rees, Wayne M.,Thompson, Jeffrey S.,et al.
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p. 233 - 246
(2007/10/02)
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- Complexes of the Platinum Metals. Part 30. Fragmentation Reactions of Rhodium and Iridium Trichloro- and Tribromo-acetates
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The nitrosyl complexes (M = Rh or Ir) react readily with trichloroacetic acid in acetone solution at ambient temperature to afford the dichloro-complexes in excellent yield.The rhodium-based reaction performed at ca. 0 deg C and quickly worked-up affords the carboxylate complex which is stable in pure acetone, but rapidly converts to the dichloride when free trichloroacetic acid and triphenylphosphine are introduced to the solution.The complexes , , mer-, and also react with trichloroacetic acid to form trichloroacetates which undergo similar ligand fragmentation reactions.Reaction pathways involving formation of CCl3(1-), Cl(1-), :CCl2, and CO2 fragments are outlined; hydrolysis of dichlorocarbene affords carbonyl ligands.Similar reactions have been observed with tribromoacetic acid.
- Boyar, Esther B.,Robinson, Stephen D.
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p. 2113 - 2120
(2007/10/02)
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- REACTION OF POWDERED IRIDIUM WITH CHLORINE AND CARBON MONOXIDE: SOME NEW CHLOROCARBONYL DERIVATIVES OF IRIDIUM
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In a search for better methods of preparing carbonyl compounds of the transition metals the reaction of powdered iridium with carbon monoxide and chlorine under various conditions has been studied.The outcome of the reaction depends on the CO/Cl2 ratio and on the temperature.The iridium(II) complex Ir(CO)2Cl (1) has been isolated, and its reactions with CO, AsPh4Cl, PPh3 and Cl- ions examined.The anion (IrCOCl4>- has been isolated as its caesium and bis(triphenylphosphine)iminium salts, and the complex Ir2(CO)4Cl6 has been identified by mass spectrometry.
- Canziani, Franco,Tuissi, Mario,Angoletta, Maria
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p. 169 - 174
(2007/10/02)
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- Cycloaddition Reactions of Azide Ligands in Phosphane Complexes of Palladium(II), Platinum(II), and Iridium(I)
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Nitriles are added to the azide ligands of the planar compounds cis-(R3P)2Pt(N3)2 and trans-(Ph3P)2Ir(CO)N3 to give to 5-R-tetrazolato complexes 1 - 3.Kinetic studies show that the rate of the -cycloaddition increases with donor strength of the phosphane ligands and with electron-poor nitriles.The mechanism of the reactions is discussed.Using HCl or acyl chlorides, from 3 and (Ph3P)2Pd(5-R-tetrazolate)2 the free 5-R-tetrazoles or disubstituted tetrazoles are obtained under mild conditions. (Ph3P)2Pd(N3)2 reacts with MeO2CCCCO2Me to give the triazolato complexes 5, 6.Organic isothiocyanates and thiocyanates yield tetrazolinethionato (7) and 5-(methylthio)tetrazolato complexes (8).Using 1H NMR spectroscopy isomeric complexes with these ambidentate heterocyclic ligands can be detected.
- Kreutzer, Peter H.,Weis, Johann Ch.,Bock, Henning,Erbe, Juergen,Beck, Wolfgang
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p. 2691 - 2707
(2007/10/02)
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- Preparation and interconversion of two isomeric iridium trihydrides
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The preparation, separation, and structural characterization of a,b,c-trihydrido-f-carbonylbis(triphenylphosphine)iridium(III) and a,b,f,-trihydrido-d-carbonylbis(triphenylphosphine)iridium(III) are described. The kinetics of interconversion of the two isomers and of the displacement of H2 from both isomers by triphenylphosphine have been measured and indicate that interconversion occurs via reversible reductive elimination/oxidation sequence. Both the isomerization and substitution reactions are postulated to involve the intermediate IrH(CO)P2. The relationship of the present results to other studies of the stereochemistry of oxidative additions to square-planar iridium(I) complexes is discussed.
- Harrod,Yorke
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p. 1156 - 1159
(2008/10/08)
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