53433-12-8Relevant academic research and scientific papers
Reaction Behavior of Decacarbonyldimetalates(2-) (M = Cr and Mo) towards the Nitrosyl Carbonyls of Iron and Cobalt
B?ttcher, Hans-Christian
, p. 410 - 412 (2017)
The reaction of the nitrosyl carbonyl complexes [Fe(NO)2(CO)2] and [Co(NO)(CO)3] with the decacarbonyldimetalates [M2(CO)10]2– (M = Cr and Mo) in THF as the solvent at room temperature was investigated. Thereby a substitution of one nitrosyl ligand towards carbon monoxide was observed in each case. Both reactions afforded the known metalate complexes [Fe(NO)(CO)3]– and [Co(CO)4]–, respectively. These species were isolated as their corresponding PPN salts [PPN+ = bis(triphenylphosphane)iminium cation] in nearly quantitative yields. The products were unambiguously identified by their IR spectroscopic and elemental analytic data as well as by their characteristic colors and melting points.
DOUBLE DEOXYGENATION OF PPN(NO2) USING METAL CARBONYL CLUSTERS OF COBALT, RHODIUM, AND IRIDIUM
Stevens, Robert E.,Liu, Phillip C. C.,Gladfelter, Wayne L.
, p. 133 - 144 (1985)
The reaction of PPN(NO2) with M4(CO)12 (M = Co, Rh) gives the nitrido clusters - in 13 and 21percent yields, respectively.A high yield synthesis (77percent) of - directly from Rh(CO)16 and PPN(NO2) is also presented.PPN(NO2) reacts with Ir4(CO)12 to give the new isocyanato cluster, - in 34percent yield, while the direct synthesis of this isocyanate product occurs in 77percent yield from PPN(N3) and Ir(CO)12.Modifications of published procedures for the preparation of 2 and Ir6(CO)16 are reported that allow shorter reaction times and give higher yields.The reaction of Ir6(CO)16 with one equivalent of PPN(NO2) generates a new cluster, PPN, in 57percent yield which is proposed to contain a bent nitrosyl ligand.An additional equivalent of PPN(NO2) gives (PPN)2 in 84percent yield with the evolution of N2O as well as CO2.
The synthesis of heteronuclear transition metal clusters derived from alkylidyne tricobalt cluster precursors. I. The reaction of (μ3-CCl)Co3(CO)9 with transition metal carbonyl anions. The crystal and molecular structure of (μ3-CCl)
Duffy, D. Neil,Kassis, Maram M.,Rae, A. David
, p. 97 - 104 (2007/10/02)
Metal exchange reactions were used to produce heterometallic clusters derived from alkylidyne tricobalt precursors. Reaction of the cluster (μ3-CCl)Co3(CO)9 with the potassium salt of (η5-C5H5)Mo(CO)3- produced (μ3/s
Reaction of metal carbonyl anions with metal carbonyl dimers: Thermodynamic and kinetic factors that control the reactions
Corraine, M. Shauna,Atwood, Jim D.
, p. 2315 - 2318 (2008/10/08)
The reactions of mononuclear metal carbonyl anions, M- (M- = Co(CO)4-, CpFe(CO)2-, Re(CO)5-, Mn(CO)4L-, L = PPh3, PBu3, P(OPh)3, CpM(CO)3- (M = Cr, Mo, W)) with metal carbonyl dimers, M′2 (M′2 = Co2(CO)8, Cp2Fe2(CO)4, Re2(CO)10, Mn2(CO)10, Cp2M2(CO)6 (M = Cr, Mo, W), and Cp2Ru2(CO)4)), are described: 2M- + M′2 → M2 + 2M′- To determine the thermodynamic parameters, we have derived values for the two-electron-reduction potentials (M2 + 2e- → 2M-) and shown that these values correctly predict the direction of reaction. The order of these reduction potentials is (all are negative) Co2(CO)8 > Cp2Cr2(CO)6 > Cp2Mo2(CO)6 > Mn2(CO)10 > Re2(CO)10 > Cp2Fe2(CO)4. In each case a clean reaction is observed with only M2 and 2M′- produced. The kinetics show that the rate has a first-order dependence on [M-]; rate = k[M-][M′2]. All dimers that contain a cyclopentadienyl ligand react more rapidly than expected from the potential. Product distributions for reactions of heterobimetallic complexes are also consistent with a different mechanism for dimers with a cyclopentadienyl ligand.
Synthesis and reactivity of the metal-substituted borane (CO)4CoBH2·THF. Preparation of the ambiphilic clusters (CO)9Co3C(CH2)nOH (n = 4, 5)
Basil, John D.,Aradi, Allen A.,Bhattacharyya, Nripendra K.,Rath, Nigam P.,Eigenbrot, Charles,Fehlner, Thomas P.
, p. 1260 - 1270 (2008/10/08)
The reaction Co2(CO)8 + 2BH3·THF → 2(CO)4CoBH2·THF (I) + H2 has been demonstrated to occur cleanly at -15°C in THF. I has been characterized by low-temperature 11B NMR and infrared spectroscopies as well as classical chemical analysis. The formation of I bears a remarkable similarity to that of (CO)4CoSiR3. Displacement of the bound THF of I occurs with Lewis bases, and the Lewis acidity of I relative to that of BH3·THF for SMe2 has been estimated. Displacement of [Co(CO)4]- from I occurs easily; e.g., reaction with PhMgBr yields PhBH2. I readily accepts hydride from [HFe2(CO)8]-, losing [Co(CO)4]- but reduces the CO ligands of hydride-free metal carbonylate anions. I is a very active reducing agent and above 10°C cleaves THF and condenses with hydrocarbyl and metal fragments to yield a mixture of clusters including an unusual tailed cluster (CO)9Co3C(CH2)nOH (n = 4,5) (II). A deuterium labeling experiment showed that four of the n carbons in the hydrocarbyl chain of II arise from THF. The results of an X-ray diffraction study suggest association of II in the solid state. [Crystals of II (the ratio of II with n = 5/n = 4 is 4) form in the space group R3 with unit cell parameters a = 34.409 (15) A?, b = 34.398 (21) A?, c = 8.575 (5) A?; β = γ = 90°, γ = 120°, V = 8789.8 A?3, and Z = 18. Solution was by direct methods, and all atoms were refined to R1 = 0.077 and R2 = 0.096 for 1443 independent reflections (Fo > 3σ(Fo)). Because of the disorder caused by the cocrystallization of species with different chain lengths, the last two atoms at the OH end of the chain could not be fully defined.] Association of II in solution is shown by a 1H NMR study, thereby demonstrating that II behaves as an ambiphilic cluster.
Oxidation-reduction of carbonylcobalt cation-anion pairs in coupling to dimeric cobalt carbonyls
Lee,Kochi
, p. 567 - 578 (2008/10/08)
The carbonylcobalt cation Co(CO)3(PPh3)2+ reacts with the anionic Co(CO)3PPh3- upon mixing to afford quantitative yields of the dimeric Co2(CO)6(PPh3)2. The same coupling occurs with the analogous Bu3P-substituted cation-anion pair to produce Co2(CO)6(PBu3)2, but at a significantly attenuated rate. Cross couplings of the substitution-inert Co(CO)3P2+ and Co(CO)3P′-, as well as the reverse phosphine combination, afford mixtures of Co2(CO)6P2, Co2(CO)6PP′ and Co2(CO)6P′2 diagnostic of extensive ligand (P,P′) scramblings. Facile ligand exchange of reactive intermediates is also indicated by the production of only Co2-(CO)6(PBu3)2 from Co(CO)3(PPh3)2+ and Co(CO)3PPh3- when carried out in the presence of added PBu3-without materially affecting the coupling rate. The marked solvent and salt effects together with the observation of characteristic charge-transfer absorption bands point to the contact ion pairs [Co(CO)3P2+] [Co(CO)3P′-] as critically involved in the rate-limiting activation process. A general mechanistic formulation is presented in Scheme II, in which the contact ion pair evolves into the radical pair consisting of the 19-electron Co(CO)3P2? and the 17-electroh Co(CO)3P′?. The behavior of these carbonylcobalt radicals is independently established in the preparative and transient electrochemistry of their precursors Co(CO)3P2+ and Co(CO)3P′- in reduction (Ec) and oxidation (Ea), respectively. Indeed the reactivity patterns in ion-pair, annihilation parallel the differences in the redox potentials J(Ec - Ea) as a direct measure of the driving force for electron transfer. Cyclic voltammetry is shown to be a particularly useful probe to demonstrate (i) the rapid dimerization rates of the 17-electron radicals to afford dicobalt carbonyls and (ii) the facile exchange of phosphine ligands between Co(CO)3P? and Co(CO)3P′? via the highly labile 19-electron intermediates Co(CO)3PP′?. Although the electron-transfer mechanism in Scheme II accounts for all the experimental observations relating to ion-pair annihilation, the possibility of alternative nonradical pathways previously proposed is also discussed.
Steric and Electronic Factors That Control Two-Electron Processes between Metal Carbonyl Cations and Anions
Zhen, Yueqian,Feighery, William G.,Lai, Chung-Kung,Atwood, Jim D.
, p. 7832 - 7837 (2007/10/02)
Reactions of metal carbonyl cations (Mn(CO)6(+), Re(CO)6(+), Mn(CO)5PPh3(+), Mn(CO)4(PPh3)2(+), Mn(CO)5PEt3(+), Mn(CO)5PPh2Me(+), Re(CO)5PPh3(+), and CpFe(CO)3(+)) with metal carbonyl anions (Co(CO)3PPh3(-), Co(CO)4(-), Mn(CO)5(-), Mn(CO)4PPh3(-), Mn(CO)4PEt3(-), Mn(CO)4PPh2Me(-), Mn(CO)3(PPh3)2(-), CpFe(CO)2(-), Re(CO)5(-), and Re(CO)4PPh3(-)) are reported.Peak potentials are reported for all ions, and nucleophilicites (as measured by reaction with MeI) are reported for the anions.Reaction of any metal carbonyl cation with any metal carbonyl anion leads ultimately to binuclear products, which are the thermodynamic products.The binuclear products are formed by single-electron transfer.In over half of the reactions between metal carbonyl cations and anions, a two-electron change results in a new metal carbonyl cation and anion.The two-electron change may be considered mechanistically as a CO(2+) transfer with the more nucleophilic of the two anions retaining the CO(2+).The kinetic and thermodynamic driving forces and the suggested mechanism are examined.
Sensitized photoreduction of cobalt(II) and iron(II). Structural characterization of 2)2PF6
Lin, Jiann T.,Wang, Shiow Y.,Yeh, Show K.,Chow, Yuan L.
, p. C17 - C21 (2007/10/02)
Triplet-state ketones readily sensitized the photoreduction of bis(acetylacetonato)cobalt(II) or Cosolv2+ under atmospheric pressure of carbon monoxide to give Co(CO)4-.The low-valent cobalt could be trapped and isolated as phosphine-substituted metal carbonyl complexes.The crystal structure of one of the products, 2)2>PF6 has been determined.It is orthorhombic, space group Pbca, Z=8, with unit cell dimensions a 19.704(5), b 24.850(13), c 21.865(9) Angstroem.Phosphine-substituted iron(0) carbonyl complexes have also been isolated from similar photoreductions of iron(II) species.
Solution Homolytic Bond Dissociation Energies of Organotransition-Metal Hydrides
Tilset, Mats,Parker, Vernon D.
, p. 6711 - 6717 (2007/10/02)
The homolytic bond dissociation energies (BDEs) of the mononuclear metal carbonyl hydride complexes (η5-C5H5)M(CO)3H (M = Cr, Mo, W), (η5-C5Me5)Mo(CO)3H, (η5-C5H5)W(CO)2(PMe3)H, (η5-C5H5)M(CO)2H (M = Fe, Ru), H2Fe(CO)4, Mn(CO)4PPh3H, Mn(CO)5H, Re(CO)5H, and Co(CO)3LH (L = CO, PPh3, P(OPh)3) have been estimated in acetonitrile solution by the use of a thermochemical cycle that reguires knowledge of the metal hydride pKa and the oxidation potential of its conjugate base (anion).The BDE values obtained by this method fall in the range 50-67 kcal/mol.In mostcases, these results agree well with literature data.Our data provide strong support for the common assumption that the M-H bond energies are greater for third-row and for second-row metals than for first-row metals, the difference being 5-11 kcal/mol.Effects of neither phosphine or phosphite substitution nor permethylation of the cyclopentadienyl ring on the M-H bond energies could be detected within the error limits of the method.The results are discussed in relation to previous M-H BDE estimates and metal hydride reactivity patterns.
Tri- and tetranuclear palladium-cobalt clusters containing bridging Ph2PCH2PPh2 (dppm) ligands. Crystal structures of [Pd2Co2(μ3-CO)2(CO) 5(μ-dppm)2] and [Pd2Co(μ3-CO)2(CO) 2(μ-dppm)2][PF6]
Braunstein, Pierre,De Méric De Bellefon, Claude,Ries, Michel,Fischer, Jean,Bouaoud, Salah-Eddine,Grandjean, Daniel
, p. 1327 - 1337 (2008/10/08)
The heterotetranuclear cluster [Pd2Co2(CO)7(dppm)2] (1) was synthesized in high yield by the reaction of [Co(CO)4]- with [Pd2Cl2(dppm)2] (dppm = μ-Ph2PCH2PPh2), whereas the A-frame complexes [Pd2Cl2(μ-Y)(dppm)2] (Y = CO, CH2) are much less reactive. The molecular structure of 1·2.5THF has been determined by X-ray diffraction. Crystal data: triclinic, space group P1 with Z = 2, a = 18.417 (8) A?, b = 14.798 (6) A?, c = 13.855 (6) A?, α = 113.61 (2)°, β = 107.50 (2)°, γ = 82.20 (2)°, V = 3299 A?3, R = 0.055, Rw = 0.076. This cluster contains a metalloligated triangular core of which two edges are bridged by the dppm ligands in such a way that the four P atoms and the four metal atoms are almost coplanar. The lability of the P→Pd bond of the precursor complex accounts for the easy formal insertion of the Co(CO)3 fragment into this bond. A metal-exchange reaction can be thermally induced that transforms 1 into the triangular cluster [PdCo2(CO)5(dppm)2]. The reaction of 1 with anionic nucleophiles X- was found to regioselectively break the exocyclic Pd-Co bond, and it afforded the clusters [Pd2CoX-(CO)3(dppm)2] (X = Cl, Br, I, OH, SCN). The reversibility of this reaction was investigated, and the reaction leading to the halogeno clusters was best carried out in acetone, proceeding faster depending upon the nature of X- (I- ≈ Br- ? Cl-) and of the corresponding cation (PPN+ ? K+, Na+). Re-formation of the exocyclic Pd-Co bond was observed in Et2O. The cationic cluster [Pd2Co(CO)4(dppm)2]+ was prepared by carbonylation of the halide-substituted Pd2Co clusters in the presence of a halide abstractor. Its unique Pd-bound terminal CO ligand is very labile and can be reversibly and selectively replaced by a solvent molecule (acetone, THF, MeCN) depending upon CO partial pressure. The molecular structure of [Pd2Co(CO)4(dppm)2]-[PF 6]·C3H6O (7·acetone) has been determined by X-ray diffraction. Crystal data: monoclinic, space group Cc with Z = 4, a = 22.87 (2) A?, b = 14.198 (4) A?, c = 22.27 (2) A?, β = 122.35 (5)°, V = 6109 A?3, R = 0.053, Rw = 0.069. The structure of the cation may be considered as derived from that of 1 by the replacement of the terminally bound Co(CO)4 unit by a carbonyl group. Spectroscopic IR and 1H and 31P{1H} NMR data are discussed in relation with the structure and reactivity of these new clusters. The synthesis and chemistry of 1 are characterized by reactions formally taking place within the Pd2P4 plane. The bonding description of the clusters with a Pd2Co(dppm)2 core emphasizes their belonging to a new class of clusters where an anionic 18-electron metal carbonyl fragment is part of a closo structure.
