- Structural analogues of the bimetallic reaction center in acetyl CoA synthase: A Ni - Ni model with bound CO
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Models for the active site of the acetyl CoA synthase (ACS) were synthesized by attachment of Cu+ and Ni(0) to nickel diaminodithiolate (S2N2) and diamidodithiolate (S2N2-) complexes. The Ni-Ni species form stable CO adducts, i.e., [{(CO)2Ni}{NiS2N2-}]2-, whereas the Cu-NiS2N2 and Cu-NiS2N2- models do not. These results provide supporting evidence for a biological role for reduced nickel in ACS. Copyright
- Linck, Rachel C.,Spahn, Cameron W.,Rauchfuss, Thomas B.,Wilson, Scott R.
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- Functionally substituted monocyclopentadienyl compounds. Formation of and derivatives with other phosphines. X-Ray crystal structure of
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reacts with (X = Cl, Br, I, CN, SCN) to give monocyclopentadienyl complexes.The reactions of these complexes with tertiary phosphines or carbon monoxide are described.The crystal structure of has been determined, and shows the nickel atom to be in a pseudo-pentacoordinate environment.
- Ballester, L.,Perez, S.,Gutierrez, A.,Perpinan, M. F.,Gutierrez-Puebla, E.,et al.
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- Metal nitrosyls. III. The reaction of nitric oxide with nickel carbonyl
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The reaction of nitric oxide with nickel carbonyl in polar and nonpolar solvents leads to a variety of compounds derived from the species [NiNO]+. When this reaction is carried out in the presence of cyclopentadiene there is almost complete conversion to nitrosylcyclopentadienylnickel.
- Feltham, Robert D.,Carriel, Jonathan T.
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- SYNTHESES OF ?-CYCLOBUT-1-EN-3-ONYL COMPLEXES BY CYCLOADDITION OF KETENES TO SOME TRANSITION METAL ALKYNYL COMPLEXES
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Reactions of ketenes (R1R2C=C=O) with (η5-C5H5)Ni(PPh3)-CCR (1) and (η5-C5H5)Fe(CO)(L)-CCR (III, L = CO and PPh3) give ?-cyclobut-1-en-3-onyl complexes, (VI) and (IX)>, (2+2) cycloaddi
- Hong, Pangbu,Sonogashira, Kenkichi,Hagihara, Nobue
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- The reactivity of a nucleophilic nickel acylate complex
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The reactivity of a nucleophilic nickel acylate complex with a tungsten carbene complex, Fe(CO)5, Cr(CO)6, PPh3, and CO was investigated. With the tungsten carbene complex, a methyl transfer occurred. With the metal carbonyl complexes, the acylate group on the nickel and a carbonyl on the iron or chromium traded places. With the PPh3 and CO, the acylate anion was replaced by the phosphine or CO ligand.
- Hermanson, James R.,Figley, Timothy M.,Seibert, Anna L.,Pinhas, Allan R.
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- Nickel-Catalyzed Decarbonylative Cyanation of Acyl Chlorides
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Ni-catalyzed decarbonylative cyanation of acyl chlorides with trimethylsilyl cyanide has been achieved. This transformation is applicable to the synthesis of an array of nitrile compounds bearing a wide range of functional groups under neutral conditions. The step-by-step experimental studies revealed that the reaction sequences of the present catalytic reaction are oxidative addition, transmetalation, decarbonylation, and reductive elimination.
- Wang, Zhenhua,Wang, Xiu,Ura, Yasuyuki,Nishihara, Yasushi
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supporting information
p. 6779 - 6784
(2019/08/26)
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- Synergy between Experimental and Computational Chemistry Reveals the Mechanism of Decomposition of Nickel-Ketene Complexes
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A series of (dppf)Ni(ketene) complexes were synthesized and fully characterized. In the solid state, the complexes possess η2-(C,O) coordination of the ketene in an overall planar configuration. They display similar structure in solution, except in some cases, the η2-(C,C) coordination mode is also detected. A combination of kinetic analysis and DFT calculations reveals the complexes undergo thermal decomposition by isomerization from η2-(C,O) to η2-(C,C) followed by scission of the C=C bond, which is usually rate limiting and results in an intermediate carbonyl carbene complex. Subsequent rearrangement of the carbene ligand is rate limiting for electron poor and sterically large ketenes, and results in a carbonyl alkene complex. The alkene readily dissociates, affording alkenes and (dppf)Ni(CO)2. Computational modeling of the decarbonylation pathway with partial phosphine dissociation reveals the barrier is reduced significantly, explaining the instability of ketene complexes with monodentate phosphines.
- Staudaher, Nicholas D.,Arif, Atta M.,Louie, Janis
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supporting information
p. 14083 - 14091
(2016/11/06)
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- Synthesis and reactions of mono- and dinuclear Ni(I) thiolate complexes
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The dinuclear and mononuclear nickel(I) thiolates, [Ni(PPh 3)(μ-SR)]2 (1a: R is 2,4,6-triisopropylphenyl (Tip), 1b:R is 1-adamantyl (Ad)), (DxpS)Ni(μ-SDxp)Ni(PPh3)(2) (Dxp is 2,6-dixylylphenyl), and Ni(SDmp)(PPh3)(3) (Dmp is 2,6-dimesitylphenyl), have been synthesized by the reaction of the nickel(I) amide Ni{N(SiMe3)2}(PPh3)2 with the corresponding thiols. The two nickel centers of 1a and 1b are equivalent, and are linked by two thiolato sulfurs and aNi-Ni bond, whereas the two inequivalent nickels of 2 are connected by a SDxp sulfur, a η2/η 3-xylyl group of the other SDxp ligand, and a Ni-Ni bond. A slightly bulkier m-terphenyl thiolate, SDmp, prevents its nickel complex from forming a Ni-Ni bond, and the mononuclear nickel(I) center of 3 is bound to PPh 3 and SDmp through interactions with the sulfur and a η2-mesityl. The coordinatively unsaturated nickel(I) complex 3 is reactive, and the reaction of 3 with TEMPO generated diamagnetic Ni(SDmp)(PPh3)(O, N:η2-TEMPO) (4). N-Heterocyclic carbenes, 1,3,4,5-tetramethylimidazolin-2-ylidene (IMe′) and 1,3-bis-(2,4,6-trimethylphenyl)imidazolin-2-ylidene (IMes), also react with 3 to afford a dinuclear nickel(I) complex, [Ni(IMe′)(μ-SDmp)]2 (5), and a mononuclear nickel(I) complex, Ni(SDmp)(IMes) (6), respectively. The reaction of 3 with 1 equiv of tBuNC afforded the dinuclear complex [Ni(CNtBu)(μ-SDmp)]2 (7), whereas the analogous reaction with 1 equiv of CO resulted in a mixture of Ni(PPh3) 2(CO)2 and Ni(CO)(SDmp)2(PPh3)(8).
- Ito, Mikinao,Matsumoto, Tsuyoshi,Tatsumi, Kazuyuki
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p. 2215 - 2223
(2009/08/08)
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- Synthetic, structural, and thermochemical studies of N-heterocyclic carbene (NHC) and tertiary phosphine ligands in the [(L)2Ni(CO)2] (L = PR3, NHC) system
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Two new dicarbonyl N-heterocyclic carbene nickel(0) complexes of the type (NHC)2Ni(CO)2 (NHC = ICy, [N,N′- bis(cyclohexylimidazol)-2-ylidene (2), IMes [N,N′-bis(2,4,6- trimethylphenyl)imidazol)-2-ylidene] (3)) have been prepared by a substitution reaction of (NHC)Ni(CO)2 (NHC = ItBu [N,N′-bis(tert- butylimidazol)-2-ylidene], IAd [N,N′-bis(1-adamantylimidazol)-2-ylidene]) and 2 equivalents of ICy or IMes. Single-crystal X-ray analyses confirmed the monomeric 18-electron compositions of [(ICy)2Ni(CO)2] (2) and [(IMeS)2Ni(CO)2] (3). The greater electron-donating properties of the NHC ligands compared to tertiary phosphines are also demonstrated through calorimetric studies and enabled the determination of average bond dissociation enthalpies for Ni-L (L = NHC and tertiary phosphine).
- Scott, Natalie M.,Clavier, Herve,Mahjoor, Parisa,Stevens, Edwin D.,Nolan, Steven P.
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p. 3181 - 3186
(2009/02/04)
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- Reaction of C(NMe2)4 with Ni(CO)4 - syntheses and structures of [C(NMe2)3][(CO)3NiC(O)NMe2], [C(NMe2)3]2[Ni5(CO)12], and[C(
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The reaction of C(NMe2)4 with Ni(CO)4 in THF produces the carbamoyl complex [C(NMe2)3][(CO)3NiC(O)-NMe2] (1); side products are the purple cluster compound [C(NMe2)su
- Petz
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p. 2274 - 2280
(2008/10/08)
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- Reaction of carbodiphosphorane Ph3P=C=PPh3 with Ni(CO)4. Experimental and theoretical study of the structures and properties of (CO)3NiC(PPh3)2 and (CO)2NiC(PPh3)2
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The carbodiphosphorane Ph3P=C=PPh3 (1) readily reacts with Ni(CO)4 in toluene to give the substitution product (CO)3NiC(PPh3)2 (2). If the reaction is carried out in THF solution, additionally red crystals of the dicarbonyl complex (CO)2NiC(PPh3)2 (3) are formed. 2 smoothly converts into 3 when dissolved in THF. The compounds have been characterized by single-crystal X-ray diffraction. Quantum chemical calculations at the DFT level of theory (B3LYP) are given for the geometries of model compounds 1a-3a with PH3 ligands instead of PPh3, which are in good agreement with the experimental results for 1-3. The metal-ligand bond energies are also predicted at B3LYP. The calculated Ni-C(PH3)2 bond energy of 3a (D0 = 33.7 kcal/mol) is nearly the sum of the Ni-C(PH3)2 (D0 = 20.9 kcal/mol) and first Ni-CO bond energy of 2a (D0 = 16.3 kcal/mol). The analysis of the metal-ligand bonding using the CDA method shows that there is mainly ligand → metal donation and much less metal → ligand back-donation between Ni and C(PH3)2 in 2a. Donation and back-donation become stronger and back-donation becomes more important in 3a than in 2a.
- Petz, Wolfgang,Weller, Frank,Uddin, Jamal,Frenking, Gernot
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p. 619 - 626
(2008/10/08)
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- Synthesis and reactivities of novel η2-(C,O) alkylphenylketene complexes of nickel. Coordination-mode switching reaction of the ketene ligand
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A series of bis(tertiary phosphine)(alkylphenylketene)nickel complexes, Nia), C2H5 (b); L = P(C6H5)3 (1), P(C6H5)2(p-CH3C6H4) (2)>, were isolated from the reaction of bis(1,5-cyclooctadiene)nickel with alkylphenylketene in the presence of the corresponding tertiary phosphines.The spectroscopic analyses of 1 and 2 suggest η2-(C,O) to be a ketene structure close to the structure of oxanickelacyclopropane.Based on their chemical reactivities and fluxional behaviors in 1H and 13C NMR, the ketene moieties of 1 and 2 switch their coordination-mode from η2-(C,O) to η2-(C,C) type via an associative process involving binuclear μ-ketene intermediates prior to undergoing further reactions.
- Miyashita, Akira,Sugai, Ryu-ji,Yamamoto, Jun-ichi
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p. 239 - 247
(2007/10/02)
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- Preparation and properties of metallacyclobutanes of nickel and palladium
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Bis(phosphine)-3,3-dimethylnickela- and palladacyclobutanes have been prepared by intramolecular C-H insertion reaction of the corresponding dineopentyl metal complexes.Nickelacyclobutane complexes decompose when heated thereby undergoing competitive carb
- Miyashita, Akira,Ohyoshi, Mayumi,Shitara, Hiroaki,Nohira, Hiroyuki
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p. 103 - 112
(2007/10/02)
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- HETERONUCLEAR COMPLEXES CONTAINING GROUP 6 TRANSITION METALS; CHEMICAL, SPECTROSCOPIC, AND THEORETICAL STUDIES ON SOME BINUCLEAR COMPLEXES AND THE X-RAY CRYSTAL STRUCTURE DETERMINATION OF (WNi(CO)3(PPh3)2(Η5-C5H5))
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Reactions of anions (M(CO)3(η5-C5H5))(-) with (NiCl2(PPh3)2) in tetrahydrofuran afford paramagnetic, bimetallic complexes (MNi(CO)3(PPh3)2(η5-C5H5)) (M=Mo (1) or W(2), and a less stable chromium analogue (M=Cr(3)), as green crystalline solids.Ready cleavage of these bimetallic complexes occurs, as on reaction with CO or Ph2PCH2Ch2PPh2, and related reactions of (WRh(CO)3(PPh3)2(η5-C5H5)) (5) are also presented.An X-ray diffraction study of crystalline (2) (monoclinic, space group P21/c, a=17.873(9), b=10.156(6), c=21.249(7) angstroem, β=105.05(3) deg, Z=4) establishes the structure ((η5-C5H5)(OC)W(μ-CO)2Ni(PPh3)2 (R=0.062, R'=0.087) with semibridging CO groups and a relatively short W-Ni separation (2.574(3) angstroem).Spectroscopic studies on complexes (1)-(3) include analyses of e.s.r. spectra both in solution, where coupling to inequivalent 31P nuclei is observed, and in the solid state.Comparative extended-Hueckel molecular orbital studies on model complexes (MM'(CO)3(PH3)2(η5-C5H5)) (M=Mo, M'=Rh; M=W, M'=Ni or Cu (two conformers)) are discussed and the bonding analysed in terms of both direct M-M' and semibridging M(μ-CO)M' interactions.Cyclic voltammetry of complexes (2), (5), and (WCu(CO)3(PPh3)2(η5-C5H5)) is reported and simple redox processes occur for (2) and (5).
- Carlton, Laurence,Lindsell, W. Edward,McCullough, Kevin J.,Preston, Peter N.
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p. 2741 - 2750
(2007/10/02)
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- Transition-Metal-Silyl Complexes, 20. - Investigations on the Reactivity of the Anionic Silyl Complexes -
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Phosphane-substituted anionic silyl complexes - (1) are distinctly more reactive than their tetracarbonyl analoga, particularly towards metal or metal-complex halides.Their solution structure depends on the corresponding cation, with which they are able to form contact ion pairs.Reaction of 1 with CH3I, Me2SiHCl or Me3SnCl (R''3EX) yields phosphanesubstituted alkyl silyl, bissilyl or silyl stannyl complexes mer-Fe(CO)3(PR'3)(ER''3)SiR3.By reaction of 1 with (Ph3PAgCl)4, Ph3PAuCl, PhHgBr, or HgBr2 (LnMX) stable hetero-binuclear complexes mer-Fe(CO)3(PR'3)(SiR3)MLn can be prepared, which contain unsupported Fe-Ag-, Fe-Au-, or Fe-Hg bonds.X-ray structure analysis of Fe(CO)3(PPh3)(SiMePh2)AuPPh3 (6) (Fe-Au 255.1 (1), Fe-Si 235.7 (3) pm) reveals that the SiMePh2 and the PPh3 ligand are cis oriented to the Fe-Au bond.
- Schubert, Ulrich,Kunz, Erika,Knorr, Michael,Mueller, Johannes
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p. 1079 - 1086
(2007/10/02)
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- Reaction of nickel polymerization catalysts with carbon monoxide
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The nickel compound, Ni(Ph2PCH=C(Ph)O)(PEt3)Ph, is a catalyst precursor for ethylene homopolymerization and the alternating copolymerization of ethylene with carbon monoxide.In the absence of ethylene, CO is a catalyst poison.In an effort to understand the mechanisms of these reactions, we have investigated the chemistry of the compounds with pure CO.The crystal structures of the catalyst precursor and the benzoyl product resulting from the insertion of CO into the Ni-Ph bond are presented.Several zero-valent complexes of Ni and an organic product based on the coupling of the chelating ligand and the benzoyl group have been isolated and characterized.A brief description of the polymerization mechanism is presented.
- Klabunde, U.,Tulip, T. H.,Roe, D. C.,Ittel, S. D.
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p. 141 - 156
(2007/10/02)
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- Metal-formaldehyde chemistry: Metal-promoted elementary transformations of formaldehyde
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Paraformaldehyde reacts with vanadocene, cp2V (I; cp = η5-C5H5), in a toluene solution to form [cp2V(η2-CH2O)] (II). The bonding mode of formaldehyde was determined by an X-ray analysis [V-C = 2.092 (8) A?, V-O = 1.955 (5) A?, and C-O = 1.353 (10) A?]. The formation of II occurred with simultaneous generation of a significant amount of HCOOMe, as a consequence of the fact that II can react further with paraformaldehyde to form HCOOMe. Disproportionation of CH2O to HCOOMe was observed when the CH2O ligand was removed from II by using carbon monoxide. Oxymethylene ligands containing a vanadium-carbon σ bond have been formed by reacting complex II with Lewis acids and alkylating agents. Lewis acids, like BF3 or TiCl4, or alkylating agents, such as Et3OBF4 or MeSO3F, gave very unstable oxymethylene compounds which underwent homolytic fission of one V-C σ bond. Stable oxymethylene compounds were isolated when the alkylation of II was carried out by using acyl halides MeCOCl and PhCOCl. Compounds isolated in crystalline forms were [cp2V(Cl)(OC(O)Me)] (VI; v(CO) = 1710 cm-1) and [cp2V(Cl)(OC(O)OPh)] (VII; v(CO) = 1690 cm-1). The ionization of the V-Cl bond in VI and VII allowed the second oxygen to bind vanadium forming metallacycles [cp2V(CH2-O-C(O)-Me)](BPh4) (VIII) and [cp2V(CH2-O-C(O)-Ph)](BPh4) (IX). The CO stretching band is significantly lowered, to 1605 cm-1 in VIII and to 1600 cm-1 in IX. An important lengthening of the V-C and C-O bond distances accompanying the acylation of formaldehyde [V-C = 2.159 (4) A? and C-O = 1.474 (5) A? in complex VIII; V-C = 2.170 (7) A?, and C-O = 1.481 (8) A? in complex IX] was observed. Complexes VIII and IX did not react or only slightly reacted with CO, inducing homolytic cleavage of the V-C bond and forming [cp2V(CO)2]+. Nickel(0)-phosphine complexes [Ni(PR3)4] (R = n-Bu, XV; R = Ph, XVI) and [Ni(PPh3)2(C2H4)] (XVII) promoted decomposition of formaldehyde to CO and H2, and they formed [Ni(PR3)3(CO)] (XVIII and XIX) and [Ni(PPh3)2(CO)2] (XX), respectively. Reaction of these complexes was stoichiometric, but for XVII the reaction was slightly catalytic when carried out in vacuo. A titanium(III) complex, [cpTi(Cl)2(THF)1.5] (XXI), was able to promote the deoxygenation of formaldehyde to ethylene, while titanium is converted into different oxo complexes, namely, [cpTi(Cl)2]2(μ-O) (XXII) and [cpTi(Cl)(μ-O)]4 (XXIII). Suggestions are given on the organometallic precursors leading to the deoxygenation of formaldehyde. Crystallographic details for complex II: space group C2/c (monoclinic); a = 13.634 (3) A?, b = 6.812 (1) A?, c = 20.528 (4) A?, β = 103.24 (2); V = 1855.9 (6) A?3; Z = 8; Dcalcd = 1.51 g cm-3. The final R factor was 0.050 (Rw = 0.051) for 820 observed reflections. Crystallographic details for complex VIII: space group P1 (triclinic); a = 14.542 (4) A?, b = 11.108 (4) A?, c = 10.019 (3) A?, α = 103.51 (3)°, β = 90.59 (3)°, γ = 110.39 (3)°; V = 1467.5 (9) A?3; Z = 2; Dcalcd = 1.30 g cm-3. The final R factor was 0.057 (Rw = 0.064) for 2949 observed reflections. Crystallographic details for complex IX: space group Cc (monoclinic); a = 11.233 (1) A?, b = 16.748 (1) A?, c = 17.475 (1) A?, β = 95.57 (1)°; V = 3272.1 (4) A?3; Z = 4; Dcalcd = 1.29 g cm-3. The final R factor was 0.037 (Rw = 0.039) for 1789 observed reflections.
- Gambarotta, Sandro,Floriani, Carlo,Chiesi-Villa, Angiola,Guastini, Carlo
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p. 2425 - 2433
(2008/10/08)
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- Preparation, structure, and properties of paramagnetic, heterobinuclear complexes containing nickel and molybdenum or tungsten. X-ray crystal structure of [NIW(CO)3(PPh3)2(η-C5H 5)]
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New paramagnetic complexes [MNi(CO)3-(PPh3)2(η-C5H 5)] (M = Mo, W) have been characterized and studied by ESR spectroscopy, EHMO calculations, and cyclic voltammetry; the structure of crystalline [NiW-(CO)3(PPh3)2(η-C5H 5)] has been determined by X-ray diffraction.
- Carlton, Laurence,Lindsell, W. Edward,McCullough, Kevin J.,Preston, Peter N.
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p. 1138 - 1140
(2008/10/08)
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- ARYL- AND ACETYLENE-NICKEL(I) COMPLEXES
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Reduction of various pentafluorophenylnickel(II) complexes in the presence of phosphines gives unstable nickel(I) compounds but Ni(C6F5)CO)2(PPh3)2 is isolated in the presence of CO.Similar NiR(CO)2(PPh3)2 (R=C6F5, C6Cl5, 2,3,5,6-C6Cl4H) are obtained by reaction of the halogenonickel(I) complex with MgRBr or LiR.Reduction of NiX2L2 in the presence of acetylenes gives 2(μ-PhCCR) (R=H, X=Cl and R=Ph, X=Cl, Br) when L=P-n-Bu3 but only NiX(PPh3)3 are recovered when L=PPh3.No reaction with the alkyne is observed for n but n reacts with RCCR' to give paramagnetic NiCl(PPh3)(CRCR') (R=Ph, R'=H, COOEt), diamagnetic 2(μ-PhCCPh) and cyclotrimerization when R=R'=COOMe.Chemical and structural behaviour of the new nickel(I) complexes is described.
- Hernandez, E.,Saez, I.,Royo, P.
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p. 249 - 256
(2007/10/02)
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- Organometallic chemistry of carbon-nitrogen multiple bonds. 4. Reductive coupling of iminium salts by nickel(0) reagents
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Reactions of [R2N=CH2]X (R = CH3, (CH3)2CHCH2; R2 = CH2(CH2CH2)2, O(CH2CH2)2; X = Cl-, Br
- Barefield, E. Kent,Carrier, Allen M.,Sepelak, Dennis J.,Van Derveer, Donald G.
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p. 1395 - 1399
(2008/10/08)
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- Electrochemical Synthesis, IX - Preparation of CO Free Metal Complexes
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The electrochemical synthesis of metal acetylacetonates (M = Cr, Mo, V, Ti) from metal anodes and acetylacetone is reported.In the presence of oxygen the oxo compounds OM(acac)2 are formed for M = Mo, V and Ti instead of M(acac)3.The electrochemical production of Ni(PPh3)4 and Fe(PMe3)4 starting from Ni(acac)2 and Fe metal, respectively, has been investigated.Successful carbonylation to Ni(CO)n(PPh3)4-n (n = 1,2) or Fe(CO)m(PMe)5-m (m = 2,3) proves the hypothesis that replacement of PR3 ligands by CO takes place after reduction of the central metal to the oxidation state 0. - Key words: Electrochemical Synthesis, Transition Metal Complexes, Acetylacetonates, Phosphane Complexes, High Pressure Carbonylation
- Grobe, Joseph,Zimmermann, Heinz
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p. 808 - 811
(2007/10/02)
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- NICKEL(II) INDUZIERTE C-C VERKNUEPFUNG ZWISCHEN KOHLENMONOXID UND ALKINEN UNTER ERHALT DER DREIFACHBINDUNG
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Acetylene and 1-alkynes react with carbon monoxide under basic conditions (amines) with nickel(II) complexes, L2NiBr2 (L=Et2NH, (C6H5)3P), to give acetylencarboxamides with maintenance of the triple bond.Intermediates are isolated, characterised and a mechanism is proposed.
- Hoberg, Heinz,Riegel, Hans Josef
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p. 245 - 250
(2007/10/02)
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- Oxidative Addition of Esters of Formic Acid and β-Lactones to Ni(0)-Complexes Involving Cleavage of the C-O Bond
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Reactions of esters of formic acid, HCOOR (R = C2H5, CH2C6H5), with Ni(0)-complexes (mixtures of bis(1,5-cyclooctadiene)nickel (Ni(cod)2) and tertiary phosphines (PR'3)), lead to decarbonylation of HCOOR to afford (Ni(CO)n(PR''3)4-n and ROH.Vinyl formate gives a mixture of CH3CHO, Ni(CO)n(PR'3)4-n, C2H4, and CO2 on interaction with the Ni(0)-complexes. β-Lactones liberate CO2 on treatment with the Ni(0)-complexes.Oxidative addition of the reactants to Ni involving cleavage of the C-O bond(s) accounts for the formation of the products.
- Yamamoto, Takakazu,Ishizu, Junichi,Yamamoto, Akio
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p. 623 - 624
(2007/10/02)
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- Reactions of nickel, palladium, and platinum complexes with carbonyl sulfide
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The complexes ML3 (M = Ni, Pd, Pt; L = PPh3, P(p-C6H4CH3)3) react with carbonyl sulfide to afford M(CO)L3, M(CO)2L2, M(η2-COS)L2, and M(COS2)L2 complexes, depending upon M, L, and reaction conditions. These reactions are contrasted with those involving CS2 in place of COS. A mechanism for the reductive disproportionation of COS by Pt(PPh3)4 involving a metal-sulfide intermediate is proposed. The dioxygen complexes Pt(O2)L2 and Pd(O2)L2 react with carbonyl sulfide to afford metal thiocarbonates, Pt(CO2S)L2 and Pd(CO2S)L2, in which the thiocarbonate ligand is asymmetrically bound to the metal.
- Gaffney, Thomas R.,Ibers, James A.
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p. 2860 - 2864
(2008/10/08)
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- Electrochemical Syntheses, V. Phosphane Substituted Metal Carbonyls of the Iron Group Elements
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The electrochemical synthesis of iron, cobalt, and nickel carbonyl derivatives with phosphane ligands from metal anodes is described. - Keywords: Electrochemical Synthesis, Metal Carbonyls, Phosphane Ligands
- Grobe, Joseph,Schneider, Bernd Heinz
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- Oxidative Addition of Aryl Carboxylates to Ni(0) Complexes Involving Cleavage of the Acyl-O Bond
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Reactions of aryl carboxylates RCOO-p-C6H4X (R=CH3, C2H5, n-C3H7; X=H, CH3, OCH3, CN) with bis(1,5-cyclooctadiene)nickel, Ni(cod)2, in the presence of phosphine ligands yield olefin (R(-H)), p-XC6H4OH, and nickel carbonyl complex(es) when the R group has a β hydrogen, whereas CH4, C2H6, nichel carbonyl complex(es), and nickel phenoxide are formed when the R group is CH3.The formation of the products is accounted for by assuming oxidative addition of the ester to nickel involving the cleavage of the acyl-O bond of RCOO-p-C6H4X followed by decarbonylation of the acylnickel complex and decomposition of the alkylnickel complex: RCOO-p-C6H4X + NiLn -> RCONiLnOC6H4X -> RNiLnOC6H4X + CO.The intermediate alkyl(phenoxo)nickel-type complex NiCH3(OC6H5) was in fact isolated in the reaction of phenyl acetate with Ni(cod)2 in the presence of 2,2'-bipyridine.The rate of the reaction is first order with respect to the concentration of the zerovalent nickel complex and the pseudo-first-order rate constant increases with with the increase in the basicity of the phosphine ligand added and with the increase of the electron-withdrawing ability of X.On the basis of these results a mechanism involving a nucleophilic attack at the carbonyl carbon by nickel is proposed.The activation parameters for the reaction of C2H5COOC6H5 with the mixture of Ni(cod)2 and PPh3 are ΔH=21+/-2 kcal/mol, ΔS=-8.8+/-2.9 eu.
- Yamamoto, Takakazu,Ishizu, Junichi,Kohara, Teiji,Komiya, Sanshiro,Yamamoto, Akio
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p. 3758 - 3764
(2007/10/02)
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- Kinetic study of the reactions of bis(cyclopentadienylcarbonylnickel) with ligands
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The kinetics of the reactions between Cp2Ni2(CO)2 (Cp = cyclopentadienyl) and mono- and bidentate ligands have been studied. The reaction with monodentate ligands proceeds by an SN2 mechanism, but the reaction with bidentate (acetylenic) ligands appears to be a two-stage mechanism with a reversible, first-order process as rate-determining step. The more probable mechanisms are discussed on the basis of the values of the activation parameters and the steric hindrance of the ligand.
- Stanghellini,Rossetti,Gambino,Cetini
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p. 2672 - 2675
(2007/10/05)
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- Kinetics and mechanism of the reactions of di-μ-carbonyl-bis(cyclopentadienyl)dinickel(0) with monodentate ligands
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The ligands carbon monoxide, triphenylarsine, triphenyl phosphite, triphenylphosphine, ethyldiphenylphosphine, and tri-n-butylphosphine react with di-μ-carbonyl-bis(cyclopentadienyl)dinickel(0) to give nickelocene and diliganddicarbonylnickel(0) (eq 1). The kinetics of these reactions have been studied by following the carbonyl region infrared spectra of reaction mixtures or by manometric observation of carbon monoxide absorption. Complicated behavior is observed with tri-n-butylphosphine. The dependence on carbon monoxide concentration was not studied, but reaction according to (1) is much slower than the rate reported for carbon monoxide exchange. For the other ligands studied, a second-order rate law, first order in each reactant, is observed: -d[Ni2(CO)2(C5H5)2]/dt = k[Ni2(CO)2(C5H5)2][L]. The reaction mechanism is discussed. A complex mechanism can be shown to be quantitatively consistent with the data for the reaction with tri-n-butylphosphine.
- Ellgen, Paul C.
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p. 232 - 239
(2008/10/08)
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