38800-77-0Relevant academic research and scientific papers
Sonochemistry and Sonocatalysis of Metal Carbonyls
Suslick, Kenneth S.,Goodale, James W.,Schubert, Paul F.,Wang, Hau H.
, p. 5781 - 5785 (1983)
Ultrasonic irradiation of liquids produces acoustic cavitation: the rapid formation, growth, and implosive collapse of vapor filled vacuoles.This generates short-lived ''hot spots'' with peak temperature ca. 3000 K and nanosecond lifetimes.We have studied the effects of high intensity ultrasound on a variety of metal carbonyls and have observed the general phenomenon of sonochemical ligand dissociation, which often produces multiple CO substitution.Fe(CO)5, for example, upon sonolysis, yields Fe3(CO)12 in the absence of additional ligands and Fe(CO)3L2 and Fe(CO)4L (L = phosphine or phosphite) in their presence.Similar substitution patterns are observed for Fe3(CO)12, Mn2(CO)10, Cr(CO)6, Mo(CO)6, and W(CO)6.In all cases examined the rates of sonochemical ligand substitution are first order in metal carbonyl concentration and independent of L concentration.In addition, ln Kobsd correlates well with solvent system vapor pressure.These results are consistent with a dissociative mechanism in which coordinatively unsatureted species are produced by the cavitation process.Further use of these transient intermediates is made as alkene isomerization catalysts.Sonocatalysis by a wide range of metal carbonyls shows many similarities to photocatalysis, but different relative efficiencies and selectivities have also been observed.
Rapid synthesis of Group VI carbonyl complexes by coupling borohydride catalysis and microwave heating
Birdwhistell, Kurt R.,Schulz, Brian E.,Dizon, Paula M.
, p. 69 - 71 (2013/01/15)
Several Group VI tetracarbonyl phosphine and tertiary amine complexes [M(CO)4 L2, M = Cr, Mo, W, L2 = 2PPh 3, dppm, dppe, dppp, dppb, bpy, phen, dppf] were synthesized in minutes in the microwave at moderate temperature, atmospheric pressure, and utilizing NaBH4 as a catalyst. The reactions were optimized by careful solvent selection. The octahedral complexes were isolated in percent yields ranging from 17 to 95. The lower temperatures, shorter reaction times, benign solvents, and lower pressures as compared to the traditional thermal syntheses provide a rapid, eco-friendly synthetic route to these common Group VI complexes.
Synthesis and characterization of 6,7 and 8-coordinate monomeric complexes of tungsten obtained from reaction of [W(CO)3(MeCN)3] with pyridine-2-thiol (pySH) and PPh3
Anjumanara,Begum, Noorjahan,Camellia, Farzana K.,Kabir, Shariff E.,Kundu, Kalipada
, p. 1123 - 1125 (2007/10/03)
Complexes [W(CO)4(PPh3)2] 1, [W(CO) 4(pySH)(PPh3)] 2, [W(CO)2(pyS) 2(PPh3)] 3 and [W(pyS)4] 4 have been obtained from the reaction of [W(CO)3(MeCN)3] with pyridine-2-thiol (pySH) and PPh3 in refluxing THF. 1 and 2 are normal 6-coordinate complexes but 3 and 4 are unusual 7 and 8-coordinate complexes, respectively. The complexes have been characterized by IR, 1H and 31P{1H}NMR, mass spectra and elemental analysis.
Organometallic chemistry in a conventional microwave oven: The facile synthesis of group 6 carbonyl complexes
Ardon, Michael,Hogarth, Graeme,Oscroft, Daniel T.W.
, p. 2429 - 2435 (2007/10/03)
Syntheses proceeding by reflux may be improved, accelerated and simplified, by carrying out the reaction in a modified conventional microwave oven. To demonstrate the potential of this method, the synthesis of over 20 group 6 organometallic compounds is reported. Hexacarbonyls, most notably Mo(CO)6, react with a range of mono, and bi, and tridentate ligands in a modified conventional microwave oven. They generally proceed without an inert atmosphere, yields are high and reaction times are short. For example, cis -[Mo(CO)4(dppe)] is prepared in >95% yield in 20 min. Reaction of Mo(CO)6 with dicyclopentadiene affords a simple one-step synthesis of [CpMo(CO)3]2 in >90% yield, which reacts further with alkynes in toluene to produce dimetallatetrahedrane derivatives, [Cp2Mo2(CO)4 (μ-RC2R)]; presumably via the in situ formation of air-sensitive [CpMo(CO)2]2. Dimolybdenum tetra-acetate is also prepared in 48% yield in 45 min, however, this reaction requires an inert atmosphere. While W(CO)6 reacts rapidly with amines to give cis diamine adducts in high yields, direct reactions with phosphines are not so clean. Bis(phosphine) complexes are, however, cleanly formed when a small amount of piperidine is added to the reaction mixture, presumably via the bis(piperidine) complex cis-[W(CO)4(pip)2]. Reactions with Cr(CO)6 generally require an inert atmosphere and proceed less cleanly, although the important synthon [Cr(CO)5 Cl][NEt4] was prepared in 30 min (74% yield), while [(η6-C6H5OMe)Cr(CO)3] can be prepared in 45% after 4 h.
Exploring the coordination chemistry and reactivity of dialkylamino- and bis(dialkylamino)-phosphines in the coordination sphere of metals
Dyer, Philip W.,Fawcett, John,Hanton, Martin J.,Kemmitt, Raymond D.W.,Padda, Ranbir,Singh, Narendra
, p. 104 - 113 (2007/10/03)
The coordination chemistry of a range of dialkylamino- and bis(dialkylamino)-phosphines, RxP(NR′2) 3-x (x = 1 or 2; R = Cl, Me, Ph, C6F5; R′ = Et, Pri), 1-7, has been studied and the resulting Group 6 tetracarbonyl and platinum dichloride bis(phosphine) complexes fully characterised. Subsequently, the reactivity of the P-N bonds of the metal-bound phosphines was probed. Treatment of R″OH (R″ = Me, Et, allyl) solutions of the bis(dialkylaminodiphenylphosphine) complexes with anhydrous HCl gas led to substitution of NR′2 by OR″; the resulting P-alkoxy complexes were isolated in excellent yields. Acidification of ethylene glycol solutions of the aminophosphine complexes afforded the corresponding bis(chlorodiphenylphosphine) derivatives. Following reaction of trans-[W(CO)4(P{NEt2}Ph2)2] with either aqueous HCl or H2SO4, trans-[W(CO) 4(P{OH}Ph2)2] could be isolated as its dichloromethane solvate in excellent yield (81%). Reactions of the bis(bis{dialkylamino} phenylphosphine) complexes under identical conditions yielded a range of unidentified products. Reactions of ligands 1-7 with [{RhCl(CO)2}2] and elemental selenium have been undertaken and the products used to assess the phosphines' donor capabilities. Depending on the substituents at phosphorus, either trans-diphosphine or cis-dicarbonyl complexes result from reaction with [{RhCl(CO)2} 2]. The sterically demanding phosphine P(NPr2 i)2Ph (5) proved unreactive towards complexation with metals, although its selenide could be prepared and isolated. In order to probe the observed lack of oxidation or complexation the molecular structure P(NPr2i)2(C6F5) has been determined by X-ray crystallography. The Royal Society of Chemistry 2003.
Photophysical and photochemical properties of W(0) and Re(I) carbonyl complexes incorporating ferrocenyl-substituted pyridine ligands
Sun, Shih-Sheng,Tran, Dat T.,Odongo, Onduru S.,Lees, Alistair J.
, p. 132 - 135 (2008/10/08)
The photophysical and photochemical properties of a series of W(O) and Re(I) carbonyl complexes incorporating ferrocenyl-substituted pyridine ligands were investigated.
Intramolecular hydrogen-bonding, cation - π, and π-stacking interactions affecting cisltrans isomerization: Hexacarbonyltungsten derivatives of pyridyl-substituted arylphosphane ligands
Hirsivaara, Leeni,Haukka, Matti,Pursiainen, Jouni
, p. 2255 - 2262 (2007/10/03)
A series of triphenylphosphane- and diphenyl(2-pyridyl)phosphane-substituted tetracarbonyltungsten derivatives has been prepared. Attractive intramolecular interactions between the phosphane ligands have been studied in both the neutral and protonated complexes; π-stacking, hydrogen-bonding, and cation - π bonding interactions were identified and were found to have an influence on the cis/trans isomerism of the complexes. It was found that the cis/trans isomerism could be switched by protonation or deprotonation of the diphenyl(2-pyridyl)phosphane derivatives. The complexes have been characterized by 31P-, 1H-, and 13C NMR spectroscopy, X-ray crystallography, IR spectroscopy, and mass spectrometry.
Crystal Structures of , and (M = Mo or W): A Comparative Study of Structure and Bonding in Complexes (E = P, As or Sb; M = Cr, Mo or W)
Aroney, Manuel J.,Buys, Irmi E.,Davies, Murray S.,Hambley, Trevor W.
, p. 2827 - 2834 (2007/10/02)
Crystal structures have been determined for , and (M = Mo or W) as part of a systematic study of a series of nine complexes (M = Cr, Mo or W; E = P, As or Sb).Trends in bond lengths and angles are rationalised in terms of streric and electronic interactions between the bonded M(CO)5 and EPh3 fragments.Comparison is made between the solid-state geometry of the free and co-ordinated EPh3.Torsion angles defining the disposition of the EPh3 groups in relation to M(CO)5 show little variation within the series.For all nine complexes the EPh3 groups have propeller geometry with small deviations from symmetric C3 structures.The studies were extended to include other related complexes.Trends in the strutural parameters of 29 such compounds are related to the steric behaviour and ?-acceptor capacity of the ligands L.It is shown that M-P bond dimensions are not adequately explained by hybridisation changes of the phosphorus atom in the ligand L.
Water-soluble organometallic compounds. 3. Kinetic investigations of dissociative phosphine substitution processes involving water-soluble group 6 metal derivatives in miscible aqueous/organic media
Darensbourg, Donald J.,Bischoff, Christopher J.
, p. 47 - 53 (2008/10/08)
Mechanistic aspects of ligand substitution reactions of group 6 metal carbonyl derivatives containing the trisulfonated phosphine P(m-C6H4SO3Na)3 (hereafter referred to as TPPTS) in pure water and water/THF media have been investigated by examination of the reactions of these derivatives with carbon monoxide as an incoming ligand. The reactions, which were carried out under 500 psi of CO in the temperature range 110-160°C, were monitored in situ by infrared spectroscopy employing a cylindrical internal reflectance reactor. Kinetic measurements show the reactions are first-order in metal complex concentration and independent of CO pressure at high CO pressures, and the rates are retarded by added TPPTS. The activation parameters for TPPTS dissociation from M(CO)5TPPTS derivatives (M = Mo, W), e.g., in 1:1 THF/H2O, ΔH? = 28.8 ± 1.4 kcal/mol and ΔS? = -4.2 ± 3.5 eu and ΔH? = 31.8 ± 1.5 kcal/mol and ΔS? = -0.73 ± 3.6 eu, respectively were shown to be quite similar to those determined for the analogous processes involving the nonsulfonated PPh3 ligand in the same solvent systems. In addition only small solvent effects were noted in going from aqueous to organic solvents for these dissociative processes. For the cis-Mo(CO)4[TPPTS]2 derivative, in which the sodium ions are encapsulated by a cryptand, kryptofix-221, a steric acceleration of TPPTS dissociation is noted relative to its PPh3 analog. The steric requirements of the TPPTS ligand were defined by X-ray structural data obtained on [Na-kryptofix-221]3[W(CO)5P(C6H 4SO3)3] and Fe(CO)4TPPTS. By way of contrast for the cis-Mo(CO)4[TPPTS]2 derivative in which the Na+ ions are free to interact with the sulfonate groups, a stabilizing effect is noted which is attributed to intramolecular interligand interactions via the Na+ cations. In the case of cis-W(CO)4[TPPTS]2 and cis-W(CO)4[PPh3]2 an intramolecular rearrangement to the corresponding trans product was observed.
Reduction of CO2 and other substrates using photochemical reactions of the W2(CO)102- complex
Silavwe, Ned D.,Goldman, Alan S.,Ritter, Robin,Tyler, David R.
, p. 1231 - 1236 (2008/10/08)
The photochemistry of the W2(CO)102- complex was investigated with the goal of determining if irradiation of this dimer generates a powerful reducing agent, presumably a 19-electron species. In general, the photochemistry of the W2(CO)102- complex is comparable to that of other metal-metal-bonded carbonyl dimers. Irradiation into the low-energy tail of the d π → σ* electronic transition of the W2(CO)102- complex led to W-W bond homolysis. The resulting 17-electron W(CO)5- radicals could be trapped with suitable ligands such as 4-cyanopyridine to give 19-electron adducts . (See ref 3 for an important definition of the phrase 19-electron adduct .) Evidence is presented that the ligands PPh3 and PBu3 also react with photogenerated W(CO)5- to form adducts: W(CO)5- + PR3 → W(CO)5PR3-. These adducts are powerful reducing agents, and they were used to reduce CO2 to formate and CO. The only organometallic product formed in the reaction was W(CO)5PPh3, the oxidized form of the 19-electron complex. In a similar manner, Mn2(CO)10 was reduced to Mn(CO)5-, Cp2Co+ to Cp2Co, benzophenone to the radical anion, and methylviologen (MV2+) to MV+. Alternative reduction mechanisms involving the W(CO)5- radical, W(CO)52-, or HW2(CO)10- as reductants were shown not to be operating. Nineteen-electron complexes generated by irradiation of Cp2Mo2(CO)6 proved incapable of reducing CO2.
