- Halophilic reactions of pentafluorohalobenzenes with transition-metal carbonyl anions
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In the present work we widen the scope of the halophilic mechanism of nucleophilic aromatic substitution, which we found earlier for the reaction of pentafluorochlorobenzene with [CpFe(CO)2]- anion, to reactions of pentafluorohalobenzenes (Hal=Cl, Br, I) with various metal carbonyl anions [Re(CO)5]-, [Mn(CO)5]- and [CpFe(CO)2]-. Nucleophilic aromatic substitution with the [CpFe(CO)2]- anion yields C6F5Fe(CO)2Cp, while with [Re(CO)5]- and [Mn(CO)5]- anions the halo(acyl)metallates cis-[C6F5(CO)M(CO)4Hal]Na (M=Mn, Re) are obtained.
- Ivushkin,Sazonov,Artamkina,Beletskaya
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- I+-abstraction versus I--displacement in the reactions of diiodoacetylene with metal carbonyl anions: X-ray structure of CMn(CO)5>
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Solid diiodoacetylene ICCI, reacts with THF solutions of the highly basic, third row, metal carbonyl anion, Re(CO)5-, exclusively by a formal I+-abstraction process producing ReI(CO)5 and Re2I2(CO)8.Under the same conditions, the less basic, first row, metal carbonyl anion, Mn(CO)5- reacts to produce not only Mn2I2(CO)8 by formal I+-abstraction but also (OC)5MnCCMn(CO)5 by I--displacement.These results may be rationalized by HSAB arguments and consideration of charge distribution in the substrate as indicated by molecular orbital calculations.The X-ray structure of (OC)5MnCCMn(CO)5 is reported.Crystals are triclinic, space group P1, with Z = 1 in a unit cell of dimensions a 6.421(2), b 6.425(2), c 9.520(2) Angstroem, α 81.86(2), β 88.55(2), γ 82.06(2) deg, and Dcalc 1.79 g cm-3.The structure was solved by the Patterson and Fourier methods and refined by full-matrix least squares to R = 0.024, Rw = 0.033 for 1372 observed reflections with Fo2 > 3.0?(Fo2).The complex is centrosymmetric and thus exhibits an eclipsed geometry in the solid state.
- Davies, Julian A.,El-Ghanam, Moneim,Pinkerton, A. Alan,Smith, Douglas A.
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p. 367 - 376
(2007/10/02)
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- Metallorganische Lewissaeuren. XL. Ein ?,?-vinylverbrueckter Dirheniumkomplex 1:η2-CH=CH2)Re(CO)5>+BF4-
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1:η2-CH=CH2)Re(CO)5>+BF4- (1) is formed by reaction of (OC)5ReFBF3 with Me3SiCH=CH2. 1 reacts with Re(CO)5- or iodide to give (OC)5ReCH2CH2Re(CO)5 and +, respecti
- Steil, Peter,Beck, Wolfgang,Stone, F. Gordon A.
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- Mechanism of Halogenation of Dimanganese, Manganese-Rhenium, and Dirhenium Decacarbonyls
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The reactions between halogens (X2 = Cl2, Br2, I2, and ICl) and M2(CO)10 (M2 = Mn2, MnRe, and Re2) in CH3CN solvent yield equal amounts of M(CO)5X and +.For X2 = I2 the rate law was shown to obey second-order kinetics, k.For M2 = Re2 the activation parameters were ΔH = 5.8+/- 0.2 kcal/mol and ΔS = -34.9 +/-0.9 cal/(mol K), for M2 = MnRe ΔH = 6.3 +/- 1.5 kcal/mol and ΔS = -41 +/- 6 cal/(mol K), and for M2 = Mn2 ΔH = 8.5 +/- 1.4 kcal/mol and ΔS = -39 +/- 5 cal/(mol K).The relative rates of halogenation follow the order Re2(CO)10 > MnRe(CO)10 > Mn2(CO)10, which opposes the order expected based upon homolysis of the metal-metal bond.The rate of iodination varies by more than a millionfold depending on the solvent.In nonpolar solvents such as decalin or toluene the oxidation proceeds slowly to yield M(CO)5I, whereas in CH3CN or CH3NO2 the reaction proceeds rapidly to produce both M(CO)5I and +.The evidence suggests that halogen attacks the metal-metal bond via one end of the dihalogen molecule and that heterolytic cleavage of the halogen-halogen bond takes place to yield free halide ion and a halogenium-bridged metal dimer.In many respects this resembles the mechanism for the bromination of alkenes.
- Schmidt, Steven P.,Trogler, William C.,Basolo, Fred
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p. 1308 - 1313
(2007/10/02)
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