cas 13007-92-6, Chromium hexacarbonyl | Articles data

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Germylene-transition metal complexes of the type X2GeM(CO)5 · THF, where M Cr or W, X F or Cl, react with 1,2 dipoles such as aldehydes, imines and oximes, by nucleophilic exchange at the germanium atom to form new stable adducts. Similar reactions were observed with various oxidizing agents (e.g. dimethylsulfoxide, nitrosobenzene, pyridine-N-oxide). The high stability of the germanium-transition metal bond in these adducts impedes their decomposition into doubly bonded germanium intermediates ({A figure is presented}, YO, NR) by methathesis.
Castel,Riviere,Satge,Ahbala
p. 123 - 132
(1987)
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Fischer,E.O. et al.
p. P29 - P32
(1969)
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Chromium-manganese selenide carbonyl complexes: Paramagnetic clusters and relevance to C = O activation of acetone
The paramagnetic even-electron cluster, [Et4N] 2[Se2Cr3(CO)10], was found to react readily with Mn(CO)5Br in acetone to produce two unprecedented mixed chromium-manganese selenide carbonyl complexes, [Et4N][Me 2CSe2{Mn(CO)4}{Cr(CO)5} 2] ([Et4N][1]) and [Et4N]2[Se 2Mn3(CO)10{Cr(CO)5}2] ([Et4N]2[2]). X-ray crystallographic analysis showed that anion 1 consisted of two Se-Cr(CO)5 moieties, which were further bridged by one isopropylene group and one Mn(CO)4 moiety. The dianionic cluster 2 was shown to display a Se2Mn3 square-pyramidal core with each Se atom externally coordinated by one Cr(CO)5 group. The formation of complex 1, presumably via C=O activation of acetone, was further facilitated by acidification of the reaction of [Et4N]2[Se2Cr3(CO)10] with Mn(CO)5Br in acetone. Complex 1 readily transformed into 2 upon treatment with Mn2(CO)10 in a KOH/MeOH/MeCN solution. Cluster 2 was a 51-electron species, which readily converted to the known 49-electron cluster [Se2Mn3(CO)9]2- upon heating and bubbling with CO. Magnetic studies of the even-electron cluster, [Et4N]2[Se2Cr3(CO) 10], and the odd-electron species, [Et4N]2[2] and [PPN]2[Se2Mn3(CO)9], were determined by the SQUID measurement to have 2, 3, and 1 unpaired electrons, respectively. In addition, the nature and formation of complexes 1 and 2 are discussed, and the magnetic properties and electrochemistry of [Se 2Cr3(CO)10]2-, 2, and [Se 2Mn3(CO)9]2- were further studied and elucidated by molecular orbital calculations at the PW91 level of density functional theory.
Shieh, Minghuey,Lin, Chien-Nan,Miu, Chia-Yeh,Hsu, Miao-Hsing,Pan, Yi-Wen,Ho, Li-Fang
p. 8056 - 8066
(2010)
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Elementary Arrhenius Parameters in the CO-for-Ethylene Dissociative Substitution of Cr(CO)5(C2H4)
Gas-phase samples of Cr(CO)5(C2H4) are prepared in situ by laser irradiation of quantitative mixtures of Cr(CO)6, CO, and C2H4.In the presence of CO and C2H4, Cr(CO)5(C2H4) decays thermally to re-form Cr(CO)6 by the mechanism of dissociative substitution.Systematic study of the rate of this reaction as a function of partial pressures of CO and C2H4 yields the elementary high-pressure limiting thermal rate constant for unimolecular dissociation of Cr(CO)5(C2H4) (k1) and the relative constant for recombination of Cr(CO)5 with CO and C2H4 (k2/k3).Measurements of k1 and k2/k3 extended over a range of precisely controlled temperatures determine Arrhenius parameters reflecting energetic and statistical properties of these elementary rate processes.
McNamara, Bruce,Becher, Dawn M.,Towns, Marcy H.,Grant, Edward R.
p. 4622 - 4626
(1994)
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Siliciumhaltige Carben-Komplexe IX. Thermische Fragmentierung von Alkoxy(triphenylsilyl)carben-Komplexen, (CO)5MC(OR)SiPh3 (M=Cr, Mo, W)
On thermolysis of (CO)3M=C(OEt)SiPh3 (M=W, Mo, Cr) in the solid state or in solution three different decomposition pathways are observed, which are unusual for Fischer-type carbene complexes; fragmentation of the complex to give triphenylsilane, ethylene
Schubert, Ulrich,Hoernig, Hannelore
p. 307 - 316
(1987)
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The Photochemical Synthesis of in Solution: I.r. Evidence for Co-ordinated Molecular Dihydrogen
(1) is synthesised by u.v. photolysis of dissolved in liquid Xe doped with H2 at 200 K and the co-ordinated molecular dihydrogen has a νH-H i.r. band at 3030 cm-1; can also be generated photochemically in n-heptane at room temperature under high pressures (100 atm) of H2.
Upmacis, Rita K.,Gadd, Gerard E.,Poliakoff, Martyn,Simpson, Michael B.,Turner, James J.,et al.
p. 27 - 30
(1985)
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Synthesis, structure, and reactivity of cyclic (arene)chromium carbene complexes
In contrast to benzannulation products obtained by photolysis, thermolysis of the chromium carbene complexes [(1,1′-biphenyl-2-yl)methoxymethylene]pentacarbonylchromium (1) and [(1,1′-biphenyl-2-yl)(dimethylamino)methylene]pentacarbonylchromium (4) provide the new cyclic arene carbene complexes {[(1′,2′,3′,4′,5′,6′-η)-1,1′- biphenyl-2-yl]methoxymethylene}dicarbonylchromium (3) and {[(1′,2′,3′,4′,5′,6′-η)-1,1′- biphenyl-2-yl](dimethylamino)methylene}dicarbonylchromium (5). The 13C NMR spectra of these new complexes have unusually high-field-shifted and low-field-shifted signals for the carbene and carbonyl carbon resonances, respectively. The complexes are remarkably stable and do not show the high electrophilic behavior typical of Fischer carbene complexes. A new protocol for the aminolysis of Fischer carbene complexes is reported. The structure of complexes 3 and 5 were determined by single-crystal X-ray diffraction studies. 3 crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 16.154 (2) A?, b = 12.256 (2) A?, c = 15.575 (2) A?, and β = 122.92 (1)°, with Z = 8. 5 crystallizes in the monoclinic space group P21/n with unit cell dimensions a = 11.47 (1) A?, b = 7.082 (7) A?, c = 20.87 (2) A?, and β = 108.13 (2)°, with Z = 4. The structures were refined by full-matrix least-squares procedures to final R = 0.028 and Rw = 0.050 for 2074 unique observed reflections for 3 and R = 0.066 and Rw = 0.101 for 1580 unique observed reflections for 5.
Merlic, Craig A.,Xu, Daqiang,Khan, Saeed I.
p. 412 - 418
(1992)
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Time-Resolved IR Study of Gas-Phase Reaction of Benzene with Group VIB Metal Pentacarbonyls and Tetracarbonyls
The gas-phase reactions of benzene and deuterated benzene (benzene-d6) with group VIB metal pentacarbonyls M(CO)5 (M=Cr and W) and tetracarbonyl W(CO)4 were probed with time-resolved infrared spectroscopy.Benzene reacts with M(CO)5 forming presumably (η2-benzene)M(CO)5 in which benzene coordinates to the metal via an isolated double bond.The rate constants for reactions of C6H6 and C6D6 with Cr(CO)5 were found to be (3.0 +/- 0.7) and (3.3 +/- 0.2) x 1013 cm3 mol-1 s-1, respectively.The corresponding values with W(CO)5 are (2.8 +/- 0.4) and (3.5 +/- 0.6) x 1013 cm3 mol-1 s-1.From the temperature dependence of the rate of dissociative loss of benzene from (η2-benzene)Cr(CO)5, a bond dissociation energy of 9.2 +/- 0.8 kcal mol-1 was determined for (η2-benzene)Cr(CO)5.The lower limit for bond dissociation energy for loss of the benzene ligand from (η2-benzene)W(CO)5 was estimated to be 11.7 kcal mol-1.Benzene reacts with W(CO)4 producing a species, presumably (η2-benzene)W(CO)4, which is stable in the milisecond time scale.The rate constants for reactions of C6H6 and C6D6 with W(CO)4 were determined to be (3.5 +/- 0.2) and (4.1 +/- 0.4) x 1013 cm3 mol-1 s-1, respectively.Secondary addition of CO to (η2-benzene)W(CO)4 forms (η2-benzene)W(CO)5, and the rate constants are (9.4 +/- 0.9) and (8.7 +/- 1.0) x 1011 cm3 mol-1 s-1, respectively, for additions of CO to (η2-C6H6)W(CO)4 and (η2-C6D6)W(CO)4.
Wang, Wenhua,Zheng, Youfeng,Lin, Jingu,She, Yongbo,Fu, Ke-Jian
p. 11921 - 11928
(1993)
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STUDY OF THE PHOTOLYSIS OF ARENETRICARBONYLCHROMIUM COMPLEXES BY IR, UV AND 1H AND 13C NMR SPECTROSCOPY
The mechanism of photolysis of arenetricarbonylchromium complexes is investigated by a number of spectral techniques.Experimental data are obtained in favour of the formation during the ArCr(CO)3 photolysis of a multicenter complex, photodecay of which leads to the formation of chromium hexacarbonyl.A mechanism for the photolysis of arenetricarbonylchromium complexes is proposed.
Domogatskaya, E. A.,Setkina, V. N.,Baranetskaya, N. K.,Trembovler, V. N.,Yavorskii, B. M.,et al.
p. 161 - 170
(1983)
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Preparation and properties of some new cobalt and chromium carbonyl derivatives of 1,4-bis(dimethylsilyl)benzene
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Mance,Miro,Van Dyke,Viswanathan
p. 635 - 637
(1981)
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Matrix isolation study into the mechanism of photoinduced cyclization reactions of chromium carbenes
The complex (CO)5Cr[C(OMe)(Me)] is known to react photochemically with N-benzyli-denemethylamine (CH3NC(Ph)H) to form a β-lactam (1,3-dimethyl-3-methoxy-4-phenyl-2-azetidinone), whereas our study shows that (CO)5W[C(OMe)(Me)] does not. Irradiation of the complexes in argon and nitrogen matrices (λ > 390 nm) resulted in a geometrical isomerization and the trapping of the syn isomers. There was no evidence from the matrix isolation experiments for the formation of a metal-ketene complex, a likely intermediate in the solution photochemistry of (CO)5Cr[C(OMe)(Me)] with respect to β-lactam formation. Three differences were observed in the matrix and solution photochemistry of (CO)5Cr-[C(OMe)(Me)] and (CO)5W[C(OMe)(Me)]. (i) (CO)5Cr[C(OMe)(Me)] undergoes CO loss upon irradiation with UV light more readily than its tungsten analogue, (ii) Upon UV irradiation of (CO)5Cr[(C(OMe)(Me)] in a nitrogen matrix bands were observed in the IR spectrum which indicated that two (CO)4(N2)Cr[C(OMe)(Me)] isomers were formed, whereas irradiation of (CO)5W[C(OMe)(Me)] under the same conditions produced only one nitrogen adduct. (iii) Irradiation of (CO)5Cr[C(OMe)(Me)] in solution and in a solid CO matrix showed that this complex underwent loss of the carbene ligand more readily than the tungsten analogue. These findings are consistent with the proposal that, upon irradiation of chromium carbenes, a ketene transient could be formed by a cleavage of the chromium-carbene σ bond and intramolecular nucleophilic attack by the carbene on a metal carbonyl. The photochemistry of the complex (CO)5Cr(OMeXbiphenyl) was studied in both argon and nitrogen matrices. This complex underwent CO loss very readily, and it is likely that this step is involved in at least one pathway of its solution photochemistry.
Gallagher, M. Louise,Greene, J. Barry,Rooney, A. Denise
p. 5260 - 5268
(1997)
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tBu2Si=Cr(CO)5 * Na(CF3SO3) * 2 THF: a salt-adduct of a chromium-silicon double bond
The salt-adduct (tBu)2Si=Cr(CO)5 * Na(CF3SO3) * 2 THF a chromium-silicon double bond has been investigated in the solid state and in solution.The triflate Na(CF3SO3) does not coordinate rigidly to 1 but exchanges rapidly in non-polar solvents (29Si-NMR 150.7 ppm).The X-ray crystal structure of 1*Na(CF3SO3) shows a Cr-Si bond distance of 2.475(1) Angstroem and an Si-O6 bond distance of 1.857(3) Angstroem.The sum of bond angles at Si is 349.5o.In the crystal the molecules of 1*Na(CF3SO3) are linked by heptacoordinate sodium ions to form a helix along the 21 direction of the unit cell (P21/c).Upon treatment with pyridine or CO, 1*Na(CF3SO3) eliminates di(tert-butyl)silylene which trimerizes to give cyclic 3. 1*Na(CF3SO3) can be transformed with HPMA (hexamethylphosphorotriamide) into (t-Bu)2(HMPA)Si=Cr(CO)5, 3.A single crystal X-ray structure determination of 3 shows a Cr-Si bond distance of 2.527(3) Angstroem and an Si-O6 bond distance of 1.777(6) Angstroem.Complex 3 can be described as a ?-donor complex (t-Bu)2(HMPA)Si -> Cr(CO)5.
Handwerker, Hermann,Paul, Martin,Riede, Juergen,Zybill, Christian
p. 151 - 156
(1993)
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Photoinduced Se-C insertion following photolysis of (η5- C4H4Se)Cr(CO)3. A picosecond and nanosecond time-resolved infrared, matrix isolation, and DFT investigation
The photochemistry of (η5;-C4H 4Se)Cr(CO)3 was investigated by matrix isolation, time-resolved infrared spectroscopy, and steady-state photochemical methods. Density functional theory (DFT) was used to assist in the identification of the photoproducts. Irradiation (λexc= 406 nm) of (η5-C4H4Se)Cr(CO)3 in either an Ar or CH4 matrix at 20 K produced the selenophene ring-opened insertion product (C,Se-C4H4Se)Cr(CO)3. Further irradiation of this matrix produced the CO-loss species (C,Se-C 4H4Se)Cr(CO)2. Pulsed irradiation at 400 nm produced the CO-loss species (η5-C4H 4Se)Cr(CO)2(S) in n-heptane (S) along with the insertion products (C,Se-C4H4Se)Cr(CO)3 and (C,Se-C 4H4Se)Cr(CO)2, both of which may have triplet character. Time-resolved measurements on the microsecond time scale confirmed that the CO-loss species (η5-C4H4Se)Cr(CO) 2(S) reacts with CO (k2 = 5.8 × 106 dm3 mol-1 s-1 at 298 K), while (C,Se-C4H 4Se)Cr(CO)3 and (C,Se-C4H4Se)Cr(CO) 2 do not react on this time scale. DFT calculations provide an explanation of the stability of the triplet (C,Se-C4H 4Se)Cr(CO)3 species in terms of a chromaselanabenzene structure, which is consistent with previously observed metal insertion into coordinated selenophene ligands.
Brennan, Peter,George, Michael W.,Jina, Omar S.,Long, Conor,McKenna, Jennifer,Pryce, Mary T.,Sun, Xue-Zhong,Vuong, Khuong Q.
p. 3671 - 3680
(2008)
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Recombination of Cr(CO)n with CO: Kinetics and Bond Dissociation Energies
The pressure dependence of the recombination kinetics of Cr(CO)5 and Cr(CO)4 with CO has been studied with the technique of time-resolved infrared laser absorption spectroscopy.The high pressure limiting rate constants are 2.1 X 106 and 7.5 X 1
Fletcher, T. Rick,Rosenfeld, Robert N.
p. 2097 - 2101
(1988)
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An experimental determination of the Cr-DMB (DMB = 3,3-dimethyl-1-butene) bond energy in Cr(CO)5(DMB): Effects of alkyl substitution on chromium-olefin bond energies in Cr(CO)5(olefin) complexes
The chromium-olefin complex Cr(CO)5(DMB) (DMB = 3,3-dimethyl-1-butene) has been studied in the gas phase using transient infrared spectroscopy. This complex forms by addition of DMB to photogenerated Cr(CO)5 with a rate constant, kL = (7.0 ± 1.5) × 10-11 cm3 molecule-1 s-1. The bond enthalpy for the DMB-Cr(CO)5 bond has been determined from the kinetics for the decay of Cr(CO)5(DMB) to be 20.1 ± 1.7 kcal/mol at 298 K. An energy decomposition analysis has been performed for a series of Cr(CO)5(olefin) complexes (olefin = DMB, ethylene, propene, 1-butene, 1-hexene, cis-2-butene, trans-2-butene, isobutene, and tetramethylethylene (TME)) using density functional theory. These calculations provide insights into trends in the chromium-olefin bond energy. The results reveal that the trend in bond energies in these complexes correlates with the number and the nature of the alkyl groups around the double bond, and that the dominant factor in this trend is the deformation energy of the olefin and Cr(CO)5, where the deformation energy is the energy required to deform the olefin ligand and the unsaturated metal centered moiety from their isolated ground-state geometries to the geometry they adopt in the bound complex.
Cedeno, David L.,Weitz, Eric
p. 4651 - 4660
(2002)
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THE MECHANISM OF THE ADDITION OF HALOALKANES TO ALKENES IN THE PRESENCE OF TRICARBONYL-η6-NAPHTHALENECHROMIUM(0)6-C10H8)>
The title reaction has been subjected to a detailed kinetic study, the results of which when taken with an examination of reaction intermediates suggest a mechanism ivolving a non-chain sequence in which acts as a catalyst, but which involves free radical intermediates.A brief comparison is made of the efficiency of a range of complexes of formula 6-arene)> in promoting addition of CCl4 to oct-1-ene.
Bland, William J.,Davis, Reg,Durrant, Jim L. A.
p. 95 - 104
(1985)
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THE EFFECT OF REPLACING CARBONYL GROUPS BY OTHER LIGANDS ON THE CATALYTIC PROPERTIES OF ARENECHROMIUM CARBONYL COMPLEXES
The activities of a series of areneCr(CO)2L complexes in catalytic hydrogenation has been studied and found to be poorer than those of the Cr(CO)3 analogs.The IR ν(CO) changes of these complexes in THF have been shown to have value in predicting catalytic properties.
Dabard, R.,Jaouen, G.,Simonneaux, G.,Cais, Michael,Kohn, D.H.,et al.
p. 91 - 101
(1980)
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Effect of temperature on N-ethylcarbazole chromium tricarbonyl complex studied by two-dimensional infrared correlation spectroscopy
Temperature-dependent variation of N-ethylcarbazole chromium tricarbonyl complex by itself without the solid support has been studied by carefully examining their IR spectra with the aid of two-dimensional correlation analysis. Two obvious stages have been observed during the heating process. In the first stage, the crystalline ECzC undergoes a slow process to change into the amorphous form due to the strong interactions of the hydrogen bonding. In the second stage, ECzC gradually decomposes, which results in the formation of Cr(CO)6. The results suggest that the interaction between the organometallics and its solid support may not have direct influence to the final product generated under the thermal treatment.
Shen, Yi,Wu, Peiyi
p. 72 - 76
(2008)
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Unprecedented allenylidene transfer from chromium to tungsten
Pyrimidylallenylidene complexes 1 ([(CO)5M=C=C=C(NC 3H3NEt)]; M = Cr (a), W (b)) were prepared in a one-pot procedure from readily available 2-ethynylpyrimidine, butyllithium, [(CO) 5M-(THF)], and triethyloxonium tetrafluoroborate. In addition to 1a,b, the homobinuclear allenylidene complexes 2a,b ([(CO)5M=C=C= C(NC3H3NEt)M(CO)5]; M = Cr, W) were formed. In 2a,b the second (CO)5M moiety is attached to the nonalkylated nitrogen atom of the pyrimidyl ring. Treatment of the chromium complex la with an excess of [(CO)5W(THF)] afforded the tungsten allenylidene complex 2b by transmetalation of the allenylidene ligand and addition of (CO) 5W. The allenylidene ligands of other chromium allenylidene complexes [(CO)5Cr=C=C=C(R1)R2] could likewise be transferred to tungsten. In contrast, the reverse transmetalation from tungsten to chromium could not be achieved. DFT calculations indicate that the reaction proceeds by an associative rather than a dissociative pathway. The initiating reaction step is coordination of a (CO)5W fragment to the C α-Cβ bond of the allenylidene ligand.
Szesni, Normen,Drexler, Matthias,Fischer, Helmut
p. 3989 - 3995
(2006)
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Pentacarbonyl(η2-cis-cyclo-octene)chromium: Photochemical Synthesis of a Useful Cr(CO)5 Transfer Reagent
(η2-Olefin)nCr(CO)6-n complexes result from the photoreactions of Cr(CO)6 with cis-cyclo-octene (n = 1) and trans-cyclo-octene (n = 1, 2); (η2-cis-cyclo-octene)Cr(CO)5, isolated as yellow solid, is labile in solution and serves as a useful Cr(CO)5 transfer reagent to produce various LCr(CO)5 derivatives, including the isotopically labelled hexacarbonyl, Cr(CO)5(13CO).
Grevels, Friedrich-Wilhelm,Skibbe, Volker
p. 681 - 683
(1984)
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Synthesis and comparison of transition metal complexes of abnormal and normal tetrazolylidenes: A neglected ligand species
To date, only few examples of tetrazolylidene carbenes coordinated to transition metal complexes have been described. A direct comparison of normal tetrazolylidenes (1,4-substitution pattern) and abnormal tetrazolylidenes (also referred to as mesoionic carbenes ; 1,3-substitution pattern) has not been performed at all. In this work, we describe coordination of both ligand types to a row of transition metals. For example, the first examples of tetrazolylidene Mo, Ag, or Ir complexes have been isolated and fully characterized. The mesoionic tetrazolylidene Ag compound 2d is shown to be a viable carbene transfer reagent. By means of NMR, IR, and Raman spectroscopy, as well as X-ray crystallography and computational results, the pronounced differences between the two ligand substitution patterns are highlighted. It is shown that simply changing the position of a methyl group from N3 to N4 in the heterocycle can cause enormous differences in ligand characteristics.
Schaper, Lars-Arne,Wei, Xuhui,Altmann, Philipp J.,Oefele, Karl,Poethig, Alexander,Drees, Markus,Mink, Janos,Herdtweck, Eberhardt,Bechlars, Bettina,Herrmann, Wolfgang A.,Kuehn, Fritz E.
p. 7031 - 7044
(2013)
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Hydroquinoid chromium complexes bearing an acyclic conjugated bridge: Chromium-templated synthesis, molecular structure, and haptotropic metal migration
The naphthohydroquinoid tricarbonyl chromium complexes 3 and 6, bearing a styryl or phenylazo moiety, have been synthesized and studied for the haptotropic metal migration along the extended π-system. Quantum chemical calculations suggested a feasible stepwise rearrangement of the Cr(CO) 3 fragment from the hydroquinoid to the other terminal phenyl ring for the azo- rather than for the ethene-bridged system. An experimental and kinetic study of the ethene-bridged complex 3 revealed a haptotropic metal shift onto the adjacent naphthalene ring to give isomer 7 and suggested a competing intermolecular decomplexation-recomplexation pathway for the coordination of the terminal phenyl ring, affording bismetalated complexes 8 and 9. Attempts of a controlled metal migration in the azo complex analogue 6 under similar conditions were unsuccessful and resulted in partial decomposition.
Hegele, Peter,Santhamma, Bindu,Schnakenburg, Gregor,Froehlich, Roland,Kataeva, Olga,Nieger, Martin,Kotsis, Konstantinos,Neese, Frank,Doetz, Karl Heinz
p. 6172 - 6185
(2010)
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LIGANDENEIGENSCHAFTEN VON Fe3(CO)9(μ3-S)(μ3-ER) (R = ALKYL, ARYL; E = P, As)
The clusters Fe3(CO)9(μ3-S)(μ3-ER) (E = P, As; R = Alkyl, Aryl) react with (CO)5M * THF (M = Cr, W) to give the violet crystalline adducts Fe3(CO)9(μ3-SM(CO)5)(μ3-ER).Spectroscopic data and X-ray structure analyses show that adduct formation occurs via th
Winter, Andreas,Jibril, Ibrahim,Huttner, Gottfried
p. 259 - 270
(1983)
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Diversity and design of metal-based carbon monoxide-releasing molecules (CO-RMs) in aqueous systems: Revealing the essential trends
The CO-releasing ability of a diverse library of primary metal carbonyl complexes has been assessed using a deoxymyoglobin-carbonmonoxymyglobin assay. A wide spectrum of rates for the CO-release process was observed in aqueous systems. For octahedral dsu
Zhang, Wei-Qiang,Atkin, Anthony J.,Thatcher, Robert J.,Whitwood, Adrian C.,Fairlamb, Ian J. S.,Lynam, Jason M.
p. 4351 - 4358
(2009)
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Preparation of α-Diazines and α-2-Pyridylazines containing (1R)-(+)-Camphor or (1R)-(-)-Fenchone Residues and their Complexes with Group 6 Metal Carbonyls
New 2,3,6,7-tetraaza-1,3,5,7-octatetraene (α-diazine) derivatives camph=N-N=CH-CH=N-N=camph I, where camph is a (1R)-(+)-camphor residue, C10H16, and fench=N-N=CH-CH=N-N=fench II, where fench is a 1R-(-)-fenchone residue, C10H16, have been obtained together with the 2'-pyridyl derivatives camph=N-N=CHC5H4N III and fench=N-N=CHC5H4N IV.The configurations around the four C=N bonds of I or II are E,E,E,E whilst those around the two azine C=N bonds in III and IV are E,E.Complexes of the types (M = Cr, Mo or W; L = I-IV), (L = I, L' = NCMe, PPh3 or AsPh3; L = II-IV, L' = PPh3), (L = III or IV) and 3-CH2CH=CH2)L> (L = I, III or IV) containing these azines as ligands have also been obtained.Complexes of II are the most unstable and these together with tetracarbonyl complexes of IV appear to show restricted rotation around the N-N bond(s) caused by the steric requirements of the methyl groups on the fenchone residue(s).All the complexes have been characterised by multinuclear NMR (1H, 13C and 31P), IR and UV/VIS spectroscopies and mass spectrometry.The crystal structures of camph=N-N=CH-CH=N-N=camph I and fench=N-N=CHC5H4N IV have been determined.
Shaw, Bernard L.,Thornton-Pett, Mark,Vessey, Jonathan D.
p. 3597 - 3606
(1994)
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Intermetallic Communication through Carbon Wires in Heterobinuclear Cationic Allenylidene Complexes of Chromium
The reaction of [(CO)5M(THF)] (M = Cr, W) with lithiated 2-ethynylquinoline followed by alkylation of the resulting alkynylpentacarbonylmetalate with [R3O]BF4 (R = Me, Et) gives allenylidene complexes in which the terminal carbon atom of the allenylidene chain is part of an N-alkylated quinoline ring. The reaction of [(CO)5M(THF)] (M = Cr, W) with lithiated 2-ethynylpyridine derivatives, Li[C≡CC5H4BrN], and [Et 3O]BF4 affords allenylidene complexes that contain a terminal six-membered N-heterocycle brominated at the 5- or 6-position. Various alkynyl groups can be introduced into the 5-position of the ring through [PdCl2(PPh3)2] -catalyzed coupling of the 5-bromo-substituted allenylidene complexes with the terminal alkynes HC≡CR′ (R′ = TMS, Ph, C10H21, 4-C 6H4-C≡CPh, 4-C6H4-C≡CH, Fc (Fc = (C5H4,)FeCp), 4-C6H4-C=CFc, 4-C 6H4-C≡CC6H4C≡CFc). The analogous replacement reaction of the 6-bromo-substituted chromium complex with HC≡CFc yields the corresponding 6-ferrocenylalkynyl-substituted complex. Desilylation of [(CO)5Cr=C=C=C(CH)2C(C≡CSiMe 3)CHNEt] (6a) gives [(CO)5Cr=C=C= C(CH) 2C(C=CH)CHNEt] (15a). CuI-catalyzed coupling of 15a with {M}-Br ({M} = Ru(CO)2Cp, Fe-(CO)2Cp*) affords the binuclear complexes [(CO)5Cr=C=C=C(CH)2C(C=C-{M})CHNEt]. The symmetrical binuclear complex is formed by oxidative coupling of 15a with [Cu(OAc) 2]. The attachment of a ferrocenyl group to the chromium center via PPh2 to give cis-[(CO)4(Ph2PFc)Cr=C=C=C(CH) 4NEt] is achieved via displacement of a cis-CO ligand in [(CO) 5Cr=C=C=C(CH)4NEt] by PPh2Fc. On addition of Co2(CO)8 to [(CO)5Cr=C=C=C(CH) 2C(C=CPh)CHNEt] a Co2(CO)6 unit adds to the C≡C bond to form a trinuclear complex. The ferrocenyl unit in [(CO) 5Cr=C=C=C(CH)2C(C≡CR)CHNEt] (R = Fc, C 6H4C≡CFc, C6H4C≡CC 6H4C≡CFc) is readily oxidized. Spectroelectrochemical studies (IR, UV/vis) confirm that in the oxidized form there is strong electronic communication of the ferrocenyl group with the (CO)5Cr unit.
Szesni, Normen,Drexler, Matthias,Maurer, Joerg,Winter, Rainer F.,De Montigny, Frederic,Lapinte, Claude,Steffens, Stefan,Heck, Juergen,Weibert, Bernhard,Fischer, Helmut
p. 5774 - 5787
(2006)
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Sulfur dioxide insertion. VI. S-sulfinatopentacarbonyl complexes of group VI and VII transition metals
A number of sulfinatopentacarbonyls of manganese(I) and rhenium(I) have been prepared by the reactions of M(CO)5R (M = Mn, R = CH3, C2H5, and CH2C6H5; M = Re, R = CH3 and CH2C6H5) with refluxing sulfur dioxide and of Mn-(CO)5C6H5 with liquid SO2 at 35-45° under pressure. Complexes containing the anions Cr(CO)5(SO2C6H5)- and W(CO)5-(SO2C6H5)-, the former being isoelectronic with Mn(CO)5(SO2C6H5), were obtained from M(CO)5I- (M = Cr and W) and sodium benzenesulfinate, but the analogous Mo(CO)5(SO2C6H5)- could not be prepared. Other attempted syntheses of M(CO)5(SO2R) (M = Mn and Re) are described and briefly discussed. All of the sulfinatopentacarbonyl complexes prepared have been assigned structures containing M-S(O)2-R linkages from the infrared and proton magnetic resonance spectral data. The infrared carbonyl stretching region spectra of the manganese and rhenium S-sulfinatopentacarbonyls are tabulated and the magnitude of the splitting of the E band is discussed in terms of the size of the metal and bulkiness of substituents on the α-carbon atom of R. Thermal and photolytic treatment of Mn(CO)5(SO2CH2C6H5) provided no evidence of desulfurylation to give Mn(CO)5CH2C6H5.
Hartman, Frederick A.,Wojcicki, Andrew
p. 1504 - 1509
(1968)
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Px ligands with a maximum of electron-donating ability. VI. 4-P4)3>(Cp''=η5-C5H3tBu2-1,3), the product of the reaction between P4 and 2 in the presence of
The reaction of P4 with 2 in the presence of leads to 4-P4)3> (Cp''=η5-C5H3tBu2-1,3) (IUPAC formula 3(PH-1κP1,2κP2,3κP3)>(κ-P1,P2,P3,P4)>>) as a final product.An X-ray structural study reveals a complex with a planar cyclo-P4 ligand capped by a Cp''Co unit.Three of the phosphorus atoms are also coordinated to groups.
Scheer, Manfred,Becker, Uta,Huffman, John C.,Chisholm, Malcolm H.
p. C1 - C3
(1993)
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Photochemistry in Liquid Xenon: Synthesis of from and N2
is produced by u.v. photolysis of dissolved in liquid xenon containing a trace of N2 and is found to be stable in solution at -79 deg C; is converted back into by irradiation with 367 nm light.
Maier II, William B.,Poliakoff, Martyn,Simpson, Michael B.,Turner, James J.
p. 587 - 589
(1980)
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Structural and reaction chemistry of the open chromocene bis(2,4-dimethylpentadienyl)chromium
The reactivity of the open chromocene Cr(2,4-C7H11)2 (C7H11 = dimethylpentadienyl) has been investigated and found to parallel that of metal allyl complexes, such as Ni(C3H5)2. Thus, exposure to an excess of dmpe (Me2PC2H4PMe2) or t-C4H9NC brings about naked chromium reactions , leading to the formation of Cr(dmpe)3 and Cr(CN(t-C4H9))6, respectively, in good yields. With amine hydrochlorides and dmpe, one pentadienyl ligand may be removed, leading to the paramagnetic, 16-electron complex Cr(2,4-C7H11)(Cl)(dmpe), which could also be prepared from CrCl2(dmpe)2 and 1 equiv of K(2,4-C7H11). Reaction of the monochloride complex with LiCH3 leads to the formation of the analogous methyl complex. Structural determinations are reported for Cr(2,4-C2H11)2 and Cr(2,4-C7H11)(Cl)(dmpe). For Cr(2,4-C7H11)2, an open-sandwich structure was found, with the average Cr-C bond distance being 2.163 (3) ?, comparable to the value of 2.169 (4) ? for chromocene. The structure has been refined to agreement indices of R = 0.040 and Rw = 0.053 in space group D44-P43212 (No. 96) with a = b = 8.090 (1) ? and c = 20.847 (3) ? for Z = 4. For Cr(2,4-C7H11)(Cl)(dmpe), an unsymmetric piano-stool geometry was observed, in which one phosphorus atom is located under the open edge of the pentadienyl ligand, while the chlorine atom and other phosphorus atom are located under the formally uncharged C(2) and C(4) atoms of the pentadienyl ligand. The structure has been refined to agreement indices of R = 0.063 and Rw = 0.056 in space group D2h15-Pbca (No. 61) with a = 12.578 (2) ?, b = 12.117 (2) ?, and c = 23.094 (5) ? for Z = 8.
Newbound, Timothy D.,Freeman, Jeffrey W.,Wilson, David R.,Kralik, Michael S.,Patton, Alan T.,Campana, Charles F.,Ernst, Richard D.
p. 2432 - 2437
(1987)
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Inenylcarben-Komplexe aus Alkinylcarben-Komplexen und elektronenreichen Alkinen
The alkoxy(phenylethynyl)carbene>pentacarbonyl complexes, (CO)5MCPh> (1) a), Et (b); M = Cr, R = Me (c)>, react with bis(diethyl-amino)ethyne, diethylaminopropyne, and methylthiopropyne, respectively, to give inenyl-carbene comples, (CO)5M1)2) = C(OR)CCPh>> (R1 = NEt2, R2 = NEt2, Me; R1 = MeS, R2 = Me), by insertion of the CC bond of the alkyne into the metal-carbene bond.The reaction is stereoselective.The structure of (CO)5WCPh>> was established by an X-ray diffraction study.
Fischer, Helmut,Meisner, Thomas,Hofmann, Josef
p. 41 - 49
(1990)
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Photochemistry of (η6-arene)Mo(CO)3 and the role of alkane solvents in modifying the reactions of coordinatively unsaturated metal carbonyl fragments
The reactions of (η6-arene)Mo(CO)2(Sol) and M(CO)5(Sol) with CO have been studied in a range of alkane solvents (Sol), and the kinetic and activation parameters have been determined (M = Cr, Mo, or W). For M = Cr the ΔH? is constant (22 ± 2 kJ mol-1), while the ΔS? term becomes less negative as the alkane chain length increases. For the larger metals the variation in kinetic and activation parameters is less significant. Solvent displacement by CO involves an interchange mechanism for the Cr system, while for Mo or W complexes the mechanism is more associative in character. The photochemistry of (η6-arene)Mo(CO)3 (arene = benzene, mesitylene, p-xylene, or hexamethylbenzene) compounds was investigated by laser flash photolysis, supported by matrix isolation and time-resolved infrared spectroscopy (TRIR). In contrast to the behavior to the analogous (η6-arene)Cr-(CO)3, it is found that the efficiency for photochemical expulsion of CO from (η6-mesitylene)-Mo(CO)3 is markedly wavelength dependent (ΦCO = 0.587, 0.120, and 0.053 at 266, 313, and 334 nm, respectively).
Breheny, Ciara J.,Kelly, John M.,Long, Conor,O'Keeffe, Siobhan,Pryce, Mary T.,Russell, Graham,Walsh, Margaret M.
p. 3690 - 3695
(1998)
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Photochemical generation of dihydrogen complexes of chromium and tungsten
Photolysis of solutions of M(CO)6 (M = Cr, W) at low temperature in the presence of hydrogen gas affords Cr(CO)5(H2) (1) and W(CO)5(H2) (2). Complexes 1 and 2 are characterized as dihydrogen complexes based on short T1 values for the hydride resonances and the observation of a large HD coupling in the HD derivatives. Irradiation of a phosphine-substituted derivative (PMe3)Cr(CO) 5 in the presence of hydrogen gas gave similar results. Thus cis-(PMe3)Cr(CO)4(H2) (3) and trans-(PMe 3)Cr(CO)4(H2) (4) were prepared and characterized by 1H and 31P NMR spectroscopy. When the photolysis reactions were carried out in methylene chloride, solvent binding competitive with hydrogen binding was observed. This was not observed in less coordinating solvents such as alkanes. Subsequent displacement of solvent by H2 leads to the dihydrogen complexes. Complexes 1 and 2 are moderately acidic, with deprotonation effected by mild bases.
Matthews, Steven L.,Heinekey, D. Michael
p. 2615 - 2620
(2006)
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Siliciumhaltige Carben-Komplexe XII. Synthese kleiner organischer Ringsysteme aus alkoxy- oder alkylthio-substituirten Silylcarben-Komplexen (CO)5MC(XEt)SiR3 (M=Cr, Mo, W; X=O, S) und davon abgeleiteten Ketenen R3Si(EtX)C=C=O
Ketenes R3Si(EtO)C=C=O (1), prepared in situ from the carbene complexes (CO)5MC(OEt)SiR3 (M=Cr, Mo, W) by reaction with CO, react with ethyl vinyl ether or cyclopentadiene by -cycloaddition.Two stereoisomeric cyclobutanone derivatives, in which the positions of the R3Si and the EtO group are interchanged, are obtained in each case.The reactions proceed with high stereoselectivity.Ethyl vinyl ether also reacts directly with the carbene complexes to yield a single stereoisomer of 1,2-diethoxy-1-silyl-cyclopropane (6).Reaction of the ethyl-thio-substituted ketene Ph3Si(EtS)C=C=O (2) with 2,3-dihydrofuran gives the corresponding cyclobutanone only as a by-product. 3-Oxa-8-silyl-1-thia-bicyclooctan-7-one (8) is formed as the main product by loss of an ethylene unit.Ketene 1 reacts with N-methyl- or N-phenylbenzimine, but not with cyclic imines, to give β-lactames.Each of these reactions also yields two stereoisomers.
Kron, Johanna,Schubert, Ulrich
p. 203 - 220
(1989)
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Unusually slow photodissociation of CO from (η6-C 6H6)Cr(CO)3 (M= Cr or Mo): A time-resolved Infrared, Matrix Isolation, and DFT investigation
The photochemistry of η6-C6H6)M(CO) 3 (M = Cr or Mo) is described. Photolysis with λexc. > 300 nm of (η6-C6H6)Cr(CO)3 in low-temperature matrixes containing CO produce
Alamiry, Mohammed A. H.,Boyle, Nicola M.,Brookes, Christopher M.,George, Michael W.,Conor, Long,Portius, Peter,Pryce, Mary T.,Ronayne, Kate L.,Sun, Xue-Zhong,Towrie, Michael,Khuong, Q. Vuong
p. 1461 - 1468
(2009/07/18)

Borylene-based direct functionalization of organic substrates: Synthesis, characterization, and photophysical properties of novel π-conjugated borirenes
Room temperature photolysis of aminoborylene complexes, [(CO) 5MdBdN(SiMe3)2] (1: M = Cr, 2: Mo) in the presence of a series of alkynes and diynes, 1,2-bis(4-methoxyphenyl)ethyne, 1,2-bis(4-(trifluoromethyl)phenyl)ethyne,
Braunschweig, Holger,Herbst, Thomas,Rais, Daniela,Ghosh, Sundargopal,Kupfer, Thomas,Radacki, Krzysztof,Crawford, Andrew G.,Ward, Richard M.,Marder, Todd B.,Fernandez, Israel,Frenking, Gernot
p. 8989 - 8999
(2009/12/04)

A laser flash photolysis, matrix isolation, and DFT investigation of (η6-C6H5Y)Cr(CO)3 (Y = NH2, OCH3, H, CHO, or CO2CH3)
The quantum yield for arene displacement from (η6-C6H5Y)Cr(CO)3 was measured in 1,1,2-trifluorotrichloroethane (Y = NH2, OCH3, H, CHO, or CO2CH3). Values of 0.24, 0.27, 0.15, 0.17, and 0.32 were obtained respectively (λexc. = 355 nm). These values are significantly higher than those measured for photoinduced arene loss in hydrocarbon solvents using the same excitation wavelength. Laser flash photolysis of (η6-C6H5Y)Cr(CO)3 in 1,1,2-trifluorotrichloroethane (λexc. = 355 nm) resulted in the rapid formation (6. Matrix isolation experiments on (η6-C6H5Y)Cr(CO)3 (Y = H or CHO) at 12 K in CH4 or CO-doped CH4 matrixes using monochromatic irradiation confirmed the presence of two discrete excited states, one leading to CO-loss and the other to arene-loss. The results correlate with the calculated electron drift in the excited state derived from density functional theory and time dependent density functional theory calculations.
Alamiry, Mohammed A.H.,Brennan, Peter,Long, Conor,Pryce, Mary T.
p. 2907 - 2914
(2008/12/21)

Spectroscopic detection and theoretical confirmation of the role of Cr 2(CO)5(C5R5)2 and ·Cr(CO)2(ketene)(C5R5) as intermediates in carbonylation of N=N=CHSiMe3 to O=C=CHSiMe3 by ·Cr(CO)3(C5R5) (R = H, CH3)
Conversion of N=N=CHSiMe3 to O=C=CHSiMe3 by the radical complexes ·Cr(CO)3C5R5 (R = H, CH3) derived from dissociation of [Cr(CO)3(C 5R5)]2 have been investigated under CO, Ar, and N2 atmospheres. Under an Ar or N2 atmosphere the reaction is stoichiometric and produces the Cr≡Cr triply bonded complex [Cr(CO)2(C5R5)]2. Under a CO atmosphere regeneration of [Cr(CO)3(C5R5)] 2 (R = H, CH3) occurs competitively and conversion of diazo to ketene occurs catalytically as well as stoichiometrically. Two key intermediates in the reaction, ·Cr(CO)2(ketene)(C 5R5) and Cr2(CO)5(C 5R5)2 have been detected spectroscopically. The complex ·Cr(13CO)2(O=13C=CHSiMe 3)(C5Me5) has been studied by electron spin resonance spectroscopy in toluene solution: g(iso) = 2.007; A(53Cr) = 125 MHz; A(13CO) = 22.5 MHz; A(O=13C=CHSiMe3) = 12.0 MHz. The complex Cr2(CO)5(C5H 5)2, generated in situ, does not show a signal in its 1H NMR and reacts relatively slowly with CO. It is proposed to be a ground-state triplet in keeping with predictions based on high level density functional theory (DFT) studies. Computed vibrational frequencies are also in good agreement with experimental data. The rates of CO loss from 3Cr2(CO)5-(C5H5) 2 producing 1[Cr(CO)2(C5H 5)]2 and CO addition to 3Cr2(CO) 5(C5H5)2 producing 1[Cr(CO)3(C5H5)]2 have been measured by kinetics and show ΔH? ? 23 kcal mol-1 for both processes. Enthalpies of reduction by Na/Hg under CO atmosphere of [Cr(CO)n(C5H5)]2 (n = 2,3) have been measured by solution calorimetry and provide data for estimation of the Cr≡Cr bond strength in [Cr(CO)2(C5H 5)]2 as 72 kcal mol-1. The complex [Cr(CO) 2(C5H5)]2 does not readily undergo 13CO exchange at room temperature or 50°C implying that 3Cr2(CO)5(C5H5) 2 is not readily accessed from the thermodynamically stable complex [Cr(CO)2(C5H5)]2. A detailed mechanism for metalloradical based conversion of diazo and CO to ketene and N2 is proposed on the basis of a combination of experimental and theoretical data.
Fortman, George C.,Kegl, Tamas,Li, Qian-Shu,Zhang, Xiuhui,Schaefer III, Henry F.,Xie, Yaoming,King, R. Bruce,Telser, Joshua,Hoff, Carl D.
p. 14388 - 14400
(2008/04/06)

Photochemical cis-trans isomerization of cis-(η6-1,2- diphenylethene)Cr(CO)3 and the molecular structure of trans-(η6-1,2-diphenylethene)Cr(CO)3
Visible irradiation of cis-(η6-1,2-diphenylethene)Cr(CO) 3 results in an efficient conversion to the trans isomer as confirmed by NMR, room-temperature UV-vis spectroscopy, and low-temperature matrix isolation studies. Laser flash photolysis of trans-(η6-1,2- diphenylethene)Cr(CO)3 at 355 nm forms a solvated dicarbonyl species, (η6-1,2-diphenylethene)Cr(CO)2. Matrix isolation studies confirm that cis to trans isomerization occurs under low-energy irradiation (γexc > 400 nm), while photolysis with γexc = 313 nm is required to induce CO loss. Time-dependent density functional theory (TDDFT) calculations predict wavelength-dependent photochemical cis to trans isomerization for low-energy (γexc: > 400 nm) irradiation, while high-energy irradiation (γexc > 300 nm) populates excited states that are labile to CO loss.
Coleman, Anthony,Draper, Sylvia M.,Long, Conor,Pryce, Mary T.
p. 4128 - 4134
(2008/10/09)

Synthesis and electronic structure of a ferroborirene
(Chemical Equation Presented) The photochemically induced transfer of a ferroborylene yielded the first metal-bound borirene (see scheme and product structure, in which the methyl substituents are omitted). Experimental and theoretical data suggest significant it derealization in the three-membered BC2 ring.
Braunschweig, Holger,Fernandez, Israel,Frenking, Gernot,Radacki, Krzysztof,Seeler, Fabian
p. 5215 - 5218
(2008/03/15)

Ethynylthioamide complexes: Synthesis, reactivity and an unusual coupling reaction with diethylaminopropyne
The reaction of [(CO)5Cr(THF)] with propynethioic acid amides, R-C≡=C-C(=S)NMe2 (R = H, SiMe3), yields the thioamide complexes [(CO)5Cr-S=C(NMe2)C≡C-H] (1a) and [(CO)5CrS=C(NMe2)C≡C-SiMe3] (1b). Treatment of solutions of la or lb with methyllithium generates, via deprotonation or desilylation, the lithium salt Li[(CO)5Cr-S= C(NMe2)C≡C] (2). On filtration over silica, 2 is readily reprotonated. Complex la is inert towards methanol, however, adds diethylamine across the C≡C bond to give the thioacrylamide complex [(CO) 5Cr-S=C(NMe2)C(H)=C(H)NMe2] (3). Thiourea displaces the thioamide ligand to give [(CO)5Cr-S=C(NH 2)2] (4). Complex la reacts with half an equivalent of diethylaminopropyne in a three-component coupling to form the homobinuclear complex [(CO)5Cr-S=C(NEt2)-C(CH3)=C(H)-C(H)= C(NMe2)-C≡C-C(NMe2)=SCr(CO)5] (5) in high yield. The solid state structures of complexes la and 5 were established by X-ray structural analyses.
Szesni, Normen,Drexler, Matthias,Weibert, Bernhard,Fischer, Helmut
p. 346 - 356
(2008/09/20)

Addition of diazoalkanes to alkyne(pentacarbonyl)-chromium and -tungsten - Formation of 3H-pyrazole complexes
Photolysis of [M(CO)6] (M=Cr, W) in CH2Cl2 at -78 °C generates [(CO)5M(CH2Cl2)]. Subsequent sequential reaction of [(CO)5M(CH2Cl2)] with terminal alkynes, H
Abd-Elzaher, Mokhles M.,Weibert, Bernhard,Fischer, Helmut
p. 6 - 13
(2007/10/03)

Rh(I) coordination chemistry of chiral α-aminophosphine(η6-arene)chromium tricarbonyl ligands
The diastereoselective addition of Ph2PH to the chiral ortho-substituted η6-benzaldimine complexes (η6-o-X - C6H4CH=NAr)Cr(CO)3 (1, X = MeO, Ar = p-C6H4OMe; 2, X = Cl, Ar = Ph) leads to the formation of the corresponding chiral aminophosphines (α-P,N) Ph2P-CH(Ar1)-NHAr2 (3, Ar1 = o-C6H4(OCH3)[Cr(CO)3], Ar2 = p-C6H4OCH3; 4, Ar1 = o-C6H4Cl[Cr(CO)3], Ar2 = Ph) in equilibrium with the starting materials. The uncomplexed benzaldimine (o-ClC6H4CH=NPh), 2′, analogously produces an equilibrium amount of the corresponding aminophosphine Ph2PCH(Ar1)-NHAr2 (4′, Ar1 = o-C6H4Cl, Ar2 = Ph). Depending on the equilibrium constant, the subsequent addition of 1/2 equiv of [RhCl(COD)]2 (COD = 1,5-cyclooctadiene) leads to either Ph2PH oxidative addition in the case of 3 or to the corresponding [RhCl(COD)(α-P,N)] complexes [RhCl(COD)(Ph2P-CH{o-C6H4Cl[Cr(CO)3]}-NHPh)] (5) and [RhCl(COD)(Ph2P-CH(o-C6H4Cl)-NHPh)] (5′) in the cases of the aminophosphines 4 and 4′. The addition of the latter ligands, as racemic mixtures, to 1/4 equiv of [Rh(CO)2Cl]2 leads to the [RhCl(CO)(α-P,N)2] complexes [RhCO(Ph2P-CH{o-C6H4Cl[Cr (CO)3]}-NHPh)2Cl] (7) or [RhCO(Ph2P-CH(o-C6H4Cl)-NHPh)2Cl] (7′) as mixtures of (Rc,Sc)/(Sc,Rc) and (Rc,Rc)/(Sc,Sc) diastereomers. The rhodium complexes 5 and 7′ have been fully characterized by IR and 31P NMR spectroscopies and X-ray crystallography. These compounds exhibit intramolecular Rh-Cl... H-N interactions in the solid state and in solution. The stability of the new rhodium complexes has been studied under different CO pressures. Under 1 atm of CO, 5 is converted to an unstable complex [RhCl(CO)2(α-P,N)], 6, which undergoes ligand redistribution leading to 7 plus an unidentified complex. This reaction is inhibited under higher CO or syngas pressure, as confirmed by the observation of the same catalytic activity in hydroformylation when styrene was added to a catalytic mixture that was either freshly prepared or left standing for 20 h under high CO pressure.
Camus, Jean-Michel,Andrieu, Jacques,Poli, Rinaldo,Richard, Philippe,Baldoli, Clara,Maiorana, Stefano
p. 2384 - 2390
(2008/10/08)

Organic syntheses via transition metal complexes. 117.1 3-Aza-1-metalla-1,3,5-hexatrienes (M = Cr, W): Generation and π-cyclization to pyrroles
The organic synthesis via transition metal complexes was studied. 3-aza-1-metallahexa-1,3,5-trienes were obtained in good yields by condensation of the (NH2-amino)carbene complexes (CO)5M=C(Ph)NH2 (M = Cr, W) with α,β-unsaturated acid amides in the presence of phosphoryl chloride and triethylamine. The hexatrienes were found to undergo thermally induced π-cyclization to pyrroles.
Aumann, Rudolf,Vogt, Dominik,Fr?hlich, Roland
p. 1819 - 1824
(2008/10/08)

Pd-catalyzed inter- and intramolecular carbene transfer from group 6 metal-carbene complexes
The use of group 6 metal-carbene complexes in inter- and intramolecular carbene transfer reactions has been studied. Thus, pentacarbonyl[(aryl)(methoxy)carbene]chromium(0) and tungsten complexes, 10, efficiently dimerize at room temperature in the presenc
Sierra,Del Amo,Mancheno,Gomez-Gallego
p. 851 - 861
(2007/10/03)

Experimental determination of the Cr-C2Cl4 bond dissociation enthalpy in Cr(CO)5(C2Cl4): Quantifying metal-olefin bonding interactions
The bond dissociation enthalpy for the Cr-C2Cl4 bond in gas-phase Cr(CO)5(C2Cl4) has been determined to be 12.8 ± 1.6 kcal/mol using transient infrared spectroscopy. The results of a density functional theory-based energy decomposition analysis are used to quantify the metal-olefin bonding interactions in terms of the bonding description provided by the Dewar-Chatt-Duncanson model (? donation and back-bonding). The bond energy decomposition analysis reveals that metal-olefin bond strengths can be strongly influenced by the Pauli repulsion energy and by the energy necessary to deform the olefin and the metal-centered moiety from their equilibrium geometries to their geometry in the final complex. Further, a comparison between the metal-olefin bond strengths and the magnitude of the electronic interactions demonstrates that the energy associated with these deformations is the determining factor in the trends in bond enthalpies in the series of complexes Cr(CO)5(C2X4) (X = H, F, Cl). Though deformation of the Cr(CO)5 moiety contributes to the overall deformation energy, the major contribution involves deformation of the olefin. This occurs as a consequence of rehybridization of the olefin as a result of metal-olefin back-bonding. The results are discussed in terms of the Dewar-Chatt-Duncanson model, which provides the accepted qualitative description of bonding in organometallic olefin complexes.
Cadenno, David L.,Weitz, Eric
p. 12857 - 12865
(2008/10/08)

Unusual reactions of cationic bridging carbyne complexes of bis(η5-cyclopentadienyl)diiron tricarbonyl with carbonylmetal anions. A route to diiron bridging carbyne complexes
The reactions of cationic carbyne complexes of diiron, [Fe2(μ-CO)(μ-CPh)(CO)2 (η5-C5H5)2]-BBr4 (1), with the anionic carbonylmetal compounds Na[M (CO)5CN] (3, M = Cr; 4, M = Mo; 5, M = W) in THF at low temperature afford the novel bridging carbyne complexes [Fe2(μ-CO)(μ-CPh)(CO)2 (η5-C5H5)2NCM(CO)5] (6, M = Cr; 7, M = Mo; 8, M = W). In contrast to the reaction of 1, the cationic carbyne complex [Fe2(μ-CO)(μ-CC6H4Me-p)(CO)2(η5-C5 H5)2]BBr4 (2) reacts with carbonylmetal anions 3-5 under the same conditions to produce the novel bridging p-tolyl(pentacarbonylcyanotungsten)carbene complexes [Fe2(μ-CO) {μ-C(C6H4Me-p)(CO)2(η5-C5H5)2 NCM(CO)5}] (9, M = Cr; 10, M = Mo; 11, M = W). However, the analogous reaction of Na[Fe(CO)4CN] with 1 yields the diiron bridging phenylcarbene complex [Fe2(μ-CO){μ- C(H)Ph}(CO)2(η5-C5H5)2] (12). The structures of 7, 8, and 11 have been established by X-ray crystallography.
Liu, Yajun,Wang, Ruitao,Sun, Jie,Chen, Jiabi
p. 3784 - 3790
(2008/10/08)

Synthesis of the germanium(I) compounds [Ge2Hal4]2- and their reductive condensation to octahedral [Ge6]2- clusters in an organometallic environment
GeI2 reacts with [M2(CO)10]2- (M = Cr, W) leading to reductive coupling of two GeI2 units to produce the [Ge2I4]2- ligands of [{(OC)5M}I2Ge-GeI2{M(CO)5}]2- (1a and 2a). The [Ph4P] salts of these anions have been characterised by X-ray structure analyses as have the [Ph4P] salts of [{(OC)5M}Cl2Ge-GeCl2{M(CO)5}]2- (lb and 2b) obtained from the iodo derivatives la and 2a by halide metathesis with [Ph4P]Cl. Treatment of GeI2 with [W2(CO)10]2- in the presence of 2,2'- bipyridine leads to [{(OC)5W}I2GeGe(bipy){W(CO)5}] (3). The digermanium ligands in 1-3 contain germanium in the unconventional formal oxidation state +I. Reductive condensation of [{(OC)5Cr}I2GeGeI2{Cr(CO)5}]2- (1a) by addition of [Cr2(CO)10]2- leads to the octahedral cluster [{(OC)5Cr}6Ge6]2- (4) in a yield of 40%. The sequence of reactions as reported describes the first systematic approach to the synthesis of [E6]2- clusters.
Renner, Gerd,Kircher, Peter,Huttner, Gottfried,Rutsch, Peter,Heinze, Katja
p. 879 - 887
(2007/10/03)

Photochemical synthesis of new (η6-arene)Cr-hydrido stannyl and (η6-arene)Cr-bis-stannyl complexes. Ligand effects on the Sn-H interaction in the hydrido stannyl compounds
Hydrido stannyl compounds containing the η2-H-SnPh3 ligand and bis-stannyl compounds containing two SnPh3 ligands have been obtained from the photolysis of (η6-arene)Cr(CO)3 and HSnPh3. New complexes with different arenes (mesitylene, trifluorotoluene and 1,4-dimethoxybenzene) have been obtained and characterized by X-ray diffraction: (η6-C6H4(OCH3) 2)Cr(CO)2(HSnPh3) (3a), (η6-C6H4(OCH3) 2)Cr(CO)2(SnPh3)2 (3b). Structural data for 3a: monoclinic; space group P21/c (No. 14); a=17.445(3), b=9.820(3) and c=16.302(5) A; Z=4; V=2539.2(12) A3; 3b: monoclinic; space group P21/n (No. 14); a=13.904(3), b=20.567(5) and c=13.911(3) A; Z=4; V=3994(2) A3. 1H-NMR as well as X-ray provided evidence for the existence of three-center two-electron bonds in the hydrido stannyl complexes. The effects of different ligands on bonding and spectroscopic parameters were studied. Arene exchange reactions of the bis-stannyl complexes, as well as reactions of some of these compounds with P(C2H5)3 and CO, were also investigated.
Khaleel, Abbas,Klabunde, Kenneth J.,Johnson, Alison
p. 11 - 20
(2007/10/03)

Transition metal complexes of chromium, molybdenum, tungsten, and manganese containing η1(S)-2,5-dimethylthiophene, benzothiophene, and dibenzothiophene ligands
Ultraviolet photolysis of hexanes solutions containing the complexes M(CO)6 (M = Cr, Mo, W) or CpMn(CO)3 (Cp = η5-C5H5) and excess thiophene (T*) (T* = 2,5-dimethylthiophene (2,5-Me2T), benzothiophene (BT), or dibenzothiophene (DBT)) produces the η1(S)-T* complexes (CO)5M(η1(S)-T*) 1-8 or Cp(CO)2Mn(η1(S)-T*) 9-11, respectively. However, when T* = DBT and M = Mo, a mixture of two products results, which includes (CO)5Mo(η1(S)-DBT), 4a, and the π-complex (CO)3Mo(η6-DBT), 4b, as detected by 1H NMR spectroscopy. Only the complexes (CO)5W(η1(S)-DBT) (1), (CO)5Cr(η1(S)-DBT) (5), and Cp(CO)2Mn(η1(S)-DBT) (9) were sufficiently stable (several days) to be isolated and characterized by elemental analyses. Rates of DBT ligand displacement by CO (1 atm) at room temperature decreased in the order 5 > 1 > 9. Single-crystal, X-ray structural determinations are reported for 1, 5, and 9. The tilt angle (θ) of the DBT ligand in these and related complexes is discussed in terms of π-back-bonding to the DBT ligand.
Reynolds, Michael A.,Guzei, Ilia A.,Logsdon, Bradley C.,Thomas, Leonard M.,Jacobson, Robert A.,Angelici, Robert J.
p. 4075 - 4081
(2008/10/08)

Coordination compounds of monoborane - Lewis base adducts: Syntheses and structures of [M(CO)5(η1-BH3·L)] (M = Cr, Mo, W; L = NMe3, PMe3, PPh3)
Photolysis of [M(CO)6] (M = Cr, W) in the presence of BH3·L (L = NMe3, PMe3, PPh3) gave isolable borane complexes [M(CO)5(η1-BH3·L)] (1a, M = Cr, L = PMe3; 1b, M = Cr, L = PPh3; 1c, M = Cr, L = NMe3; 2a, M = W, L = PMe3; 2b, M = W, L = PPh3; 2c, M = W, L = NMe3). In products 1 and 2, the monoborane - Lewis base adduct coordinates to the metal center through a B-H-M three-center two-electron bond, which was confirmed by X-ray structural analyses of 1a, 2a, and 2b at low temperature. The X-ray crystal structural analysis of 1c at ambient temperature also showed the same coordination mode, although the positions of hydrogen atoms on the boron were not determined. The 1H NMR spectra of 1 and 2 exhibit only one BH signal at -2 to -3 ppm with an intensity of 3H in the temperature range of -80 °C to room temperature. This indicates that the coordinated BH and terminal BH's are rapidly exchanging in solution even at low temperature. When [Mo(CO)6] was used as a precursor, the formation of the corresponding molybdenum - borane complexes, [Mo(CO)5(η1-BH3·L)] (3a, L = PMe3; 3b, L = PPh3; 3c, L = NMe3), was observed by NMR spectroscopy, but the complexes could not be isolated because of their thermal instability. Complexes of pyridineborane [M(CO)5(η1-BH3·NC5H 5)] (1d, M = Cr; 2d, M = W) were also observable by NMR spectroscopy. Fenske - Hall MO calculations for the model compound [Cr(CO)5(η1-BH3·PH3)] (1e) demonstrated that the bonding between the borane and metal can be described as donation of the bonding electron pair of BH to the a1 orbital of [Cr(CO)5], and that π back-donation from the metal d orbital to the antibonding σ* orbital of BH is negligible. Compounds 1-3 can be regarded as model compounds of the methane complex [M(CO)5(CH4)], which is observed in the photolyses of [M(CO)6] in methane matrixes. Structural and spectroscopic features of the ligated borane are discussed and compared with those of related compounds.
Shimoi, Mamoru,Nagai, Shin-Ichiro,Ichikawa, Madoka,Kawano, Yasuro,Katoh, Kinji,Uruichi, Mikio,Ogino, Hiroshi
p. 11704 - 11712
(2007/10/03)

Four-coordinate group-14 elements in the formal oxidation state of zero - Syntheses, structures, and dynamics of [{(CO)5Cr}2Sn(L2)] and related species
The sodium salts Na2[{(CO)5M}2EX2] (M = Cr, Mo, W; E = Ge, Sn, Pb; X = Cl, I, OOCCH3) react with 2,2′-bipyridine (bipy) to form neutral compounds [{(CO)5M}2E(bipy)] (E = Sn: 1a-1c; E = Ge: 3a; E = Pb: 4). 1,10-Phenanthroline (phen) analogues of compounds 1a-1c and 3a [{(CO)5M}2E(phen)] (E = Sn: 1d-1f, E = Ge: 3b) are as well accessible. The 2,2′-bipyridine ligand in 1 may be formally replaced by two pyridine (py) ligands resulting in [{(CO)5M}2Sn(py)2] (1g: M = Cr, 1h: M = W). The bis-bidentate ligand 2,2′-bipyrimidine (bpmd) is found to coordinate just one [{(CO)5M}2Sn] entity in [{(CO)5M}2Sn(bpmd)] (2b: M = Cr, 2c: M = W). The biimidazolato (biim) ligand binds two [{(CO)5Cr}2Sn] moieties in [{(CO)5Cr}2Sn(biim)Sn{Cr(CO)5} 2]2-, 2a. It is shown by 1H-NMR that the pyrimidine entities in these compounds (2b, 2c) are able to rotate by a full 180° turnaround with respect to one another. This process must involve complete de-coordination of at least one of the two nitrogen donors in again at least one of the chelate cycles, the activation energy for this process being around 60 kJ/ mol. By 119Sn-NMR spectroscopy of almost all of the tin compounds described it is shown that equilibria between [{(CO)5M}2Sn(L2)] and [{(CO)5M}2Sn(L)] + L exist in all cases. From the temperature dependence of the δ values it is concluded that the activation barriers for this association/ dissociation process is below 10 kJ/mol. The structures of all new compounds are documented by X-ray analyses and all compounds are characterized by the usual analytical and spectroscopical techniques.
Kircher, Peter,Huttner, Gottfried,Heinze, Katja,Schiemenz, Berthold,Zsolnai, Laszlo,Buechner, Michael,Driess, Alexander
p. 703 - 720
(2007/10/03)

The 1,3-Sn2O2-Heterocycle as a Ligand in Organometallic Compounds - Dimerization of the Inidene Species [{(CO)5M}2SnOR]- (M = Cr, W)
Dimerized inidene complexes [(CO)5M...-Sn(OR)...-M(CO)5]22- (M = CrI Wi R = Et, iPr), 1, are obtained from [{(CO)5M}2SnCl2]2- by different routes. Dimerization occurs via alkoxy-donor tinacceptor bonding by which a planar Sn2O2 ring is formed. The Sn-{M(CO)5} bonds are made in a plane vertical to this ring such that, with the R-O groups being almost coplanar with the Sn2O2 ring, the overall geometry of the compounds shows idealized D2h symmetry. - The 119Sn-NMR resonances of 1 are found at rather low fields (M ? Cr: δ ≈ 1400i M = W: δ ≈ 1170) indicating a low-lying tin-centered orbital in the LUMO range. Correspondingly EHT analyses show that the 3-center-4π System, which characterizes monomeric inidene species [LnM ...-E(X)...-MLn]n, is still prevalent in the dimeric species 1. The low-lying π *-type LUMOs of 1 are the rationale for the observed 119Sn-NMR low-field shifts of 1. The dimeric compounds 1 react with 2,4-pentanedione to form chelate compounds of the same type as those characteristically obtained from monomeric inidene complexes: [{(CO)5Cr}2SnOEt]22- (1a) reacts to give [{(CO)5Cr}2Sn(acac)]- (2). The experimental results are verified by X-ray analyses in addition to the usual spectroscopic and analytical investigations.
Kircher, Peter,Huttner, Gottfried,Heinze, Katja,Zsolnai, Laszlo
p. 1057 - 1066
(2007/10/03)

[{(CO)5Cr}6Ge6]2-, a molecular organometallic derivative of the unknown zintl ion [Ge6]2-
Octahedral clusters from p-block elements are rare; however, the only known molecular aggregate of this kind, [{(CO)5Cr}6Sn6]2-, has now been supplemented by the isoetectronic cluster [{(CO)5Cr}6Ge6]2-(1).
Kircher, Peter,Huttner, Gottfried,Heinze, Katja,Renner, Gerd
p. 1664 - 1666
(2007/10/03)

[Cr(CO)5PCl3] - A starting material for phosphorus-rich Px ligand complexes
[Cr(CO)5PCI3] reacts with different metallates K[CpxMo(CO)3] [Cpx = η5-C5H4tBu (Cp′), η5-C5H3tBu2-1,3 (Cp″)], K[Cp″Fe(CO)2], K[Cp′Cr(CO)3], K[CpNi (CO)] and Na2[Cr2(CO)10] at -78 °C in THF to yield various P2, cycloP3 and cycto-P5 ligand complexes of the formulae [Cp′-Mo(CO)2(η3-P3)] (1a), [Cp″Mo(CO)2(η3-P3)] (1b), [{Cp′Mo-(CO)2)2(μ,η2-P 2)] (2a), [{Cp″Mo(CO)2)2(μ,η2-P 2)] (2b), [Cp″Fe(η5-P5)] (3), [(Cp′Cr)2(μ,η5-P5)] (4), [|Cp′Cr(CO)2)2-(μ,η2-P 2)1 (5), [(CpNi)2(μ,η2-P 2)(Cr(CO)5)2 (6), [{(CO)5Cr)Cl2PPCl2{Cr(CO)5)] (7) and [(Cr(CO)5}2PCl] (8). Comprehensive studies of the reaction pathway leading to formation of the cyclo-P3 product la give strong indications that a sequence involving metal-halogen exchange and stepwise P-P bond formation takes place, proceeding via [{(CO)5Cr)Cl2PPCl2{Cr(CO)5)] (7) and the cydo-P3 precursor compound [(Cp′Mo(CO)3){Cp′Mo(CO)2) 2(Cr(CO)5)(μ,η3:1:1 P3)] (9). The latter two complexes have been isolated and structurally characterized. VCH Verlagsgescllschaft mbH,.
Scheer, Manfred,Schuster, Kay,Krug, Andre,Hartung, Helmut
p. 1299 - 1304
(2007/10/03)

Preferred coordination sites for metal fragments in σ,π-bimetallic complexes. Detailed mechanistic insight from heteroatom, bridging ligand, solvent, temperature, and pressure effects on the irreversible exchange of coordination sites
New heterobimetallic complexes with σ,π-bridging thiophene and selenophene ligands, (η1:η5-XCRCHCHCMn(CO)5)Cr(CO) 3 (X = S, R = H (1), R = Me (2); X = Se, R = H (3)), were synthesized from (η5-XCRCHCHCLi)Cr(CO)3 and Mn(CO)5Hal (Hal = Cl-, Br-, CF3SO3-). The complexes 1-3 irreversibly convert at O °C in acetone into the complexes (η1:η5-XCRCHCHCCr(CO)5)Mn(CO) 3 (X = S, R = H (4), R = Me (5); X = Se, R = H (6)) by exchanging coordination sites. The σ,π- exchange of coordination sites is a first-order process and rate constants for the reaction of 2 are (3.8 ± 0.1) × 10-5 and (1.1 ± 0.1) × 10-5 s-1 in acetone and cyclohexane at 15 °C, respectively. This reaction shows no significant pressure dependence. The activation entropies for the exchange process are -16 ± 6 and -30 ± 11 J/(mol K) for 1 and 2, respectively. The kinetic data suggest an intramolecular exchange mechanism involving bridging carbonyls without any direct involvement of the solvent. It is suggested that in the activated complex the metal centers are η1-bonded to the C2 of the thienyl ligand and that the free coordination sites are occupied by two bridging carbonyls. The bimetallic complexes (η1:η5-XCRCHCHCC(O)Mn(CO)5)Cr(CO) 3 (X = S, R = H (7), R = Me (8); X = Se, R = H (9)) were also isolated from the reaction mixtures and could be obtained in higher yields by working under a CO atmosphere. The inserted carbonyl in the bridging ligand inhibits the metal fragments from exchanging coordination positions. Excess BuLi leads to the formation of the trimetallic five-membered ring complexes (μ-Hal)-{μ-(η1:η1:η 5-SCRCHCHCC(O)Mn(CO)4)Cr(CO)3)Mn(CO) 4 (R = H, Hal = Cl (10); R = Me, Hal = Br (11)). The lithiated thiophene precursor exclusively attacks a carbonyl of Re(CO)5Br to give a bimetallic acylate, which after subsequent alkylation with Et3OBF4 affords the bimetallic rhenium carbene complex (η1:η5-SCHCHCHCC(OEt)Re(CO) 4Cl)Cr(CO)3 (12). The target complex (η1:η5-SCHCHCHCRe(CO)5)Cr(CO) 3 (13), which could not be converted and did not insert a carbonyl, was obtained from Re(CO)5CF3SO3 and the lithiated precursor. The structures of 7 and 10 were confirmed by single-crystal X-ray diffraction studies.
Waldbach, Thomas A.,Van Eldik, Rudi,Van Rooyen, Petrus H.,Lotz, Simon
p. 4056 - 4070
(2008/10/08)

Light-induced [6+2] cycloadditions of dienes to tricarbonyl(η6-1,355,7-cyclooctatetraene)chromium(0)
Tricarbonyl(η6-1,3,5,7-cyclooctatetraene)chromium (1) yields upon UV irradiation in ether at 233 K with 2,3-dimethyI-1,3-butadiene (2) or 2-methyl-l,3-butadiene (3) by [6+2] cycloadditions the correspondingly substituted tricarbonyl(η6-bicyclo[4.2.2]deca-2,4,7-triene)chromium complexes 4, 5a and 5b. With ammonium cerium(IV) nitrate the organic ligand of complex 4, 9-isopropenyl-9-methyl-bicyclo[4.2.2]-deca-2,4,7-triene (6) is liberated. The complexes 4, 5a and 5b were characterised by IR and NMR spectroscopy, the ligand 6 by NMR spectroscopy. VCH Verlagsgesellschaft mbH.
Kreiter, Cornelius G.,Eckert, Ralf
p. 9 - 12
(2007/10/03)

Photochemistry of (η6-2,6-X2C5H3 N)Cr(CO)3 (X = H, CH3, (CH3)3Si). First example of a photoinduced ring-slip at an (η6-arene)M(CO)3 center.
The photochemistry of (η6-2,6-X2C5H3N)Cr(CO) 3 was investigated both in low-temperature matrices (X = H or (CH3)3Si) and in room-temperature solution (X = H, CH3, or (CH3)3 Si), Room-temperature photolysis (λexc > 410 nm) in CO-saturated methanol or acetonitrile produced (η1-2,6-X2C5H3N)Cr(CCO) 5 which subsequently formed Cr(CO)6 in a secondary photochemical process (X = H or CH3), The efficiency of pentacarbonyl formation is lower in CO-saturated cyclohexane and follows the order X = H > X = CH3, Photolysis in low-temperature matrices resulted in an η6 to η1 pyridine ring-slippage (λexc = 460 nm; X = H). Visible irradiation in a CO-doped methane matrix produced (η1-C5H5N)Cr(CO)5, while in an N2 matrix fac-(η1-C5H5N)N2 2Cr(CO)3 is formed. Irradiation with λexc = 308 nm produced both the ring-slippage product and also the CO-loss product (η6-C5H5)Cr(CO)2, which in a N2 matrix is trapped as (η6- C5H5N)Cr(CO)2(N2). Time-resolved infrared spectroscopy in cyclohexane revealed only the CO-loss product (λexc = 308 nm; X = H). The apparent difference in room-temperature and low-temperature photochemistry is explained by a rapid regeneration of (η6- C5H5N)Cr(CO)3 from the η1-intermediate. This explanation was supported by laser flash photolysis experiments (λexc = 355 nm) in CO-saturated cyclohexane (Sol), where the recovery of the (η6- C5H5N)Cr(CO)3 absorption follows a biphasic time profile, whereby the faster process was assigned to the η1 to η6 transformation and the slower to the reaction Of (η6- C5H5N)Cr(CO)2(Sol) with CO. Crystals of (η6-2,6-(CH3)2C5H 3N)Cr(CO)3 and (η6-2,6-((CH3)3Si)2C 5H3N)Cr(CO)3 were characterized by X-ray diffraction.
Breheny, Ciara J.,Draper, Sylvia M.,Grevels, Friedrich-W.,Klotzbücher, Werner E.,Long, Conor,Pryce, Mary T.,Russell, Graham
p. 3679 - 3687
(2008/10/08)

Complexes with metal-phosphorus triple bonds as possible intermediates in the reactions between chlorophosphinidenes and metalates of various transition metals
The reaction of [{M′(CO)5}2PCl] (M′ = Cr, W) with various metalates ([Cp′'Mo(CO)3r, [Cp*Ni(CO)]-, [Cr2(CO)10]2-) yields the M2P2 tetrahedral complexes [(MLn)2(,rpP2){M′(CO)5} 2] (MLn= Cp'Ni, M'= Cr (1), W (2); MLn = Cp′Mo(CO)2, M′ = Cr (4); Cp" = r5-C5Mes, Cp′ = ifC5H3tBu2) and the cydo-P4 compound [{Cr(CO)4(TfP4S]Cr(CO)3)4] 6. As side products the distorted prismane [(Cp*Ni;2μ4,]4-(P2-O-P 2)H(CO)5}2] 3 and the diphosphinomethanone complex [{Cp′Mo{CO)22]2{μ 4,η2 [Cr(CO)5}2] 5 are formed. The complexes are characterised by NMR, IR, MS, and X-ray structure analysis (1-5). Studying the reaction pathway provided evidence of phosphide intermediates of the type [LnM=P→M′Ln]. VCH Verlagsgeselischaft mbH, 1996.
Scheer, Manfred,Schuster, Kay,Krug, Andre,Hartung, Helmut
p. 973 - 979
(2007/10/03)

Ir Complexes with P4 Bicyclotetraphosphane and P8 Cunean as Ligands - CO Insertion into an Ir-P Bond
The reaction of [Cp*Ir(CO)2] with white phosphorus under photochemical or thermal conditions produces the bicyclotetraphosphane complexes 1 and 2 and the cunean-type complex 3. The products were characterized by NMR, IR, and mass spectroscopy as well as by X-ray structure analyses. Complex 1 reacts with CO with insertion into a Ir-P bond to form 2 and finally [CpIr(CO)2]. VCH Verlagsgesellschaft mbH, 1996.
Scheer, Manfred,Becker, Uta,Matern, Eberhard
p. 721 - 724
(2007/10/03)

Ring expansion of spirocydie ligands in pentacarbonylchromium complexes to tetrahydroindene derivatives
Pentacarbony 1 (pentamethylenevinylidene) chromium, [(CO)5Cr=C=C(CH2)5] (1), reacts with 1-methylthio-l-propyne (2a) and N-(1-propynyl)phenothiazine (2b) by regiospecific addition of the C=C bond of the alkyne to the C=C bond of the vinylidene ligand of 1. Initially, complexes with a spirocyclic cyclobutenylidene ligand are formed, [(CO)5Cr=CC(Me)=C(SMe)t(CH2)5] (3) and [(CO)5-Cr=C-C(Me)=C{N(C6H4) 2S}C(CH2)5] (10). Subsequent thermally initiated ring expansion affords the 2-methyl4,5,6,7-tetrahydroindenyl(methyl)thioether complex [(CO)5Cr-S(Me)(Me-C9H10)] (4) and the N-(2-methyl-4,5,6,7-tetrahydroindenyl)phenothiazine complex f(CO)5Cr-S(C6H4)2 N-(Me-C9H10)] (11), respectively. In both complexes, 4 and 11, the ligand is coordinated to the metal via the sulfur atom. The constitutions were established by (H,H)-, (H,C)- and NOE-correlated NMR spectroscopy. In the reaction of 1 with 2a, in addition to 3 and 4, the metfayl(propynyl)thioetner complex f{CO)5Cr-S(Me)C=CMe] (5) was formed. An isolable 3-methylthio-substituted cyclobutenylidene complex, [(CO)5Cr=C-C(Me)=C(SMe}CPh2] (9) was obtained from [(CO)5Cr=C=CPh2] (8) and 2a. The 4,5,6,7-tetrahydroindenylthioether ligand of 11 was cleaved from the metal by exposure of 11 adsorbed on silica gel to air or by treatment of 11 with [NEt4]Br in dichloromethane. VCH Verlagsgesellschaft mbH, D-69451 1996.
Fischer, Helmut,Karl, Christoph C.,Roth, Gerhard
p. 615 - 622
(2007/10/03)

Synthesis and unusual reactivity of compounds containing silicon-phosphorus and silicon-arsenic double bonds: New silylidenephosphanes and -arsanes of the type R2Si=E(SiR3) (E = P, As)
The monomeric lithium (fluorosilyl)phosphanides Is2Si(F)P[LiLn]R (1) (Is = 2,4,6-triisopropylphenyl; L = THF, n = 2, 3; R = SiiPr3 (a), SiMe3 (b), SitBuMe2 (c), SiPh2Me (d), SiPh3 (e), Si(Naph)3 (f), SitBu2H (g), GetBu2H (h, L = DME, n = 1)) and the related lithium (fluorosilyl)arsanides Is2Si(F)As[Li(THF)2]R (3) (R = SuPr3 (a), SiPh2Me (b), SiCy2Me (c, Cy = cyclohexyl)) eliminate LiF and THF (DME) upon heating to give the corresponding silylidenephosphanes and -arsanes 2 and 4, respectively. The reactivity of the Si=E bonds (E = P (2a), As (4a)) toward P4, elemental sulfur, and tellurium is very similar and leads to the corresponding 1,2,3-triphospha-4-silabicyclo[1.1.0]butane (12) and to two isomers of arsadiphosphasilabicyclo[1.1.0]butanes, namely 1-(triisopropylsilyl)-4,4-diisityl-1-arsa-2,3-diphospha-4-silabicyclo[1.1.0] butane (13) and 3-(triisopropylsilyl)-4,4-diisityl-1-arsa-2,3-diphospha-4-silabicyclo[1.1.0] butane (14), respectively. The reaction of S8 and Te with 2a gives rise to the corresponding silaphosphathia- and telluracyclopropanes 16 and 17, respectively. The reaction of 2a with phenylacetylene yields Is2Si(C≡CPh)PH(SiiPr3) (18), and benzonitrile reacts with 2g and 4c to give the [2 + 2]-cycloadducts Is2SiE(SiR3)C(Ph)=N (E = P (19), E = As (20)). Only 4c reacts with tert-butylphosphaacetylene to give Is2SiAs(SiCy2Me)P=C(tBu) (43). 2a reacts with cyclopentadiene to provide the expected hetero Diels-Alder product (22). The reaction of 2a with benzophenone leads to the corresponding 2,1,3-silaphosphaoxetane (23), and treatment of 2a with 1,2-diphenyl-1,2-diketone unexpectedly provides the [2 + 2]-cycloadduct Is2SiP(SiiPr3)C(Ph)(COPh)O (27) as the thermodynamic product. The 2,4-di-tert-butyl-o-quinone solely yields the [2 + 4]-cycloadduct Is2SiP(SiiPr3)O(aryl)O (aryl = 2,4-di-tert-butylphenylene) (31). The cycloaddition reactions of 2a and 4a with diphenyldiazomethane, mesityl azide, and mesityl isocyanide were also investigated, and the respective [2 + n]-cycloadducts (n = 1, 2, 3) were characterized by means of NMR spectroscopy. For example, 4a reacts with diphenyldiazomethane to give the [2 + 1]-cycloadduct Is2SiAs(SiiPr3)NN=CPh2 (29). The structures of 1h, 20, 23, and 29 were determined by X-ray crystallography.
Driess, Matthias,Pritzkow, Hans,Rell, Stefan,Winkler, Uwe
p. 1845 - 1855
(2008/10/09)

Pn Ligands with Maximum Electron-Donor Capacity, 7. - Three-Component Reaction of P4-Phosphorus with xRh(CO)2> in the Presence of or . - A Method of Studying the Pathway from Tetrahedral P4 to the Planar cyclo-P4 Ligand
The reaction of P4 with xRh(CO)2> (Cpx = Cp', Cp ; Cp' = η5-C5H4tBu, Cp = η5-C5H3tBu2-1,3) in the presence of leads to xRh(CO)(η1:1-P4)4> (1a,b), 4-P4)3> (2b), and 4-P4)4> (3a).In the corresponding reaction with no P4 takes part, and (4) is formed.An X-ray structure determination of xRh(CO)(η1:1-P4)4> (1) and 4-P4)-4> (3a) indicates a stepwise (PP) bond cleavage as the transformation pathway from the P4 tetrahedron to the cyclo-P4 ligand by passing a bicyclotetraphosphane.In the cyclo-P4 ligand complex 3a all P atoms are able to coordinate to groups.However, in 4-P4)3> (2b) the additional tBu group at the Cpx ligand sterically influences the coordination behaviour of the P atoms, and only three of them are able to coordinate to units.In these syntheses the moieties promote the reaction and stabilise intermediates along the reaction pathway.Variable-temperature 31P-NMR measurements indicate for 2b the freezing of the Cp rotation at low temperature and reveals a ΔGc(excit.) (at the coalescence temperature) of 36 kJ mol-1.Surprisingly, in -(Rh-Mn) (4) the Cpx ligands are cis-oriented whereas in *RhCO)(CpMnCO)(μ-CO)2>(Rh-Mn) a trans arrangement is observed.This indicates the unusual behaviour of the Cp ligand as a rod and not as an enlarged disk like Cp* in the crystal lattice of these compounds. - Key Words: Tetraphosphorus ligands / Bond cleavage in P4, stepwise / Rhodium P4 complexes
Scheer, Manfred,Troitzsch, Christa,Hilfert, Liane,Dargatz, Manfred,Kleinpeter, Erich,et al.
p. 251 - 258
(2007/10/02)

Pentacarbonyl(1,4-diisopropyl-1,4-diazabutadiene)chromium: Isolation and reactivity of the monodentate intermediate en route to Cr(CO)4(iprop-DAB) chelate ring closure
Exchange of the olefin ligand in Cr(CO)5(η2-(Z)-cyclooctene) by 1,4-diisopropyl-1,4-diazabutadiene (iprop-DAB) yields Cr(CO)5(iprop-DAB) (1), where the potentially bidentate DAB ligand coordinates in a monodentate fashion. Complex 1 is isolated as red crystals and fully characterized (elemental analysis, IR, UV-vis, 1H NMR and 13C NMR spectra). In hydrocarbon solution at ambient temperature it decays via two competitive routes involving (a) chelate ring closure with CO extrusion to form Cr(CO)4(iprop-DAB) (2) and (b) loss of the iprop-DAB ligand and takeup of CO to form Cr(CO)6, as monitored by means of NMR, UV-vis, and IR spectroscopy. Favorable conditions for the chelate ring closure leading to 2 are the high concentration of 1, the presence of added iprop-DAB, and the absence of CO, while the opposite is true for the formation of Cr(CO)6. The decay of 1 is retarded in the presence of increasing amounts of added iprop-DAB. It essentially follows pseudo-first-order kinetics with kobs approaching a lower limiting value of 2.7 × 10-5 s-1 under Ar at 23 °C, whereby Cr(CO)4(iprop-DAB) (2) and Cr(CO)6 are formed in a ca. 20:1 ratio. Experiments at variable temperature yield ΔH≠ = 48 ± 6 kJ mol-1 and ΔS≠ = -170 ± 18 J K-1 mol-1. In the presence of added CO or (E)-cyclooctene (ECO) the decay of 1 is accelerated, whereby additional Cr(CO)6 or Cr(CO)5(η2-ECO) are formed at the expense of Cr(CO)4(iprop-DAB) (2) production. Complementary studies involving continuous irradiation of Cr(CO)6 and iprop-DAB indicate that photogenerated 1 subsequently undergoes photolytic CO dissociation with formation of 2 in addition to the thermal chelate ring closure.
Grevels, Friedrich-Wilhelm,Kayran, Ceyhan,?zkar, Saim
p. 2937 - 2943
(2008/10/08)

Rare gas-metal carbonyl complexes: Bonding of rare gas atoms to the group VI pentacarbonyls
Transient infrared spectroscopy has been used to study reactions of M(CO)5 generated by 355-nm photolysis of M(CO)6 where M = Cr, Mo, and W. At 298 K, M(CO)5 reacts with CO with bimolecular rate constants of (1.4 ± 0.2) × 10-10, (1.5 ± 0.1) × 10-10, and (1.4 ± 0.1) × 10-10 cm3 molecule-1 s-1 for Cr, Mo, and W, respectively. M(CO)5 also reacts with Xe with bimolecular rate constants of (0.9 ± 0.4) × 10-10, (0.9 ± 0.4) × 10-10, and (2.6 ± 0.2) × 10-10 cm3 molecule-1 s-1 for Cr, Mo, and W, respectively. Infrared absorptions attributed to M(CO)5Xe and W(CO)5Kr were observed. The rate of dissociative loss of the Xe atom from the M(CO)5Xe complexes was determined by the observation of the rate of regeneration of M(CO)6 in a reaction mixture consisting of M(CO)5, CO, and Xe. The bond dissociation energy for the loss of the Xe atom from M(CO)5Xe for all three metals is the same within experimental error and has an average value of 8.5 kcal/mol. A bond dissociation energy was estimated for the loss of Kr from W(CO)5Kr, and an upper limit can be estimated for the bond dissociation energy for loss of Ar from W(CO)5Ar.
Wells,Weitz, Eric
p. 2783 - 2787
(2007/10/02)

(Acylamino)carbene complexes: Synthesis, structure, and reactivity
Fischer type aminocarbene complexes of chromium, molybdenum and tungsten undergo N-acylation under DMAP catalysis followed by decarbonylation affording tetracarbonyl ((acylamino)carbene) chelate. These complexes are characterized by a short metal-carbene and a long metal-oxygen bond in the chelate ring. A remarkable chemoselectivity is observed upon reaction with alkynes which is governed by the metal and the N-substitution pattern and which may be rationalized in terms of a stereoselective alkyne insertion into the metal-carbene bond. (CO)4Cr=C(p-Tol)NRCOC(CH3)3 prefers E insertion leading either to carbene annelation (indene, naphthalene derivatives) or to double alkyne insertion products (phenol ester). The molybdenum analogues add the alkyne to give presumed Z-alkenylcarbene intermediates, reasonable precursors for the isolated pyrrol and pyrrolone cycloaddition products.
Grotjahn,Kroll,Sch?fer,Harms,D?tz
p. 298 - 310
(2008/10/08)