33011-91-5Relevant academic research and scientific papers
Kinetics and Mechanism of Substitution Reactions of Some (η3-Allyl)manganese Tetracarbonyl Compounds
Palmer, G. Todd,Basolo, Fred
, p. 3122 - 3129 (2007/10/02)
Kinetic data are reported for CO substitution of (η3-C3H4X)Mn(CO)4, where X is a substituent in the 1- or the 2-position of the allyl ligand and where X1 = H, Me, Ph, t-Bu, and Cl.Also the anti- and the syn-(η3-C3H3(1,2-Ph2))Mn(CO)4 isomers were prepared for the fist time and their rates of substitution determined.In all cases the rates of reaction are first order in substrate concentration and zero order in entering nucleophile concentrations.Studies on decarbonylation reactions of (η1-C3H5)Mn(CO)4L rule out an η3 --> η1 --> η3 mechanism.It appears that CO substitution takes place by a dissociation (SN1 process, and the kinetic parameters for (η3-C3H5)Mn(CO)4 are k(45 deg C) = 2.8 X 10-4 s-1, ΔH(excit.) = 26.8 kcal/mol, and ΔS(excit.) = 9.6 eu.Substituents on the 1-position of the allyl group have a small retardation effect on the rates of CO substitution.Substituents on the 2-position enhance the rates of reaction; furthermore, this rate enhancement increases with increasing bulkiness of the substituent.Still, the maximum rate observed was only 500 times greater than that for the parent comopound, and this is for the 2-tert-butylallyl compound.Unfortunately, all attempts to prepare the desired compounds with strong electron-donating and -withdrawing substituents on the allyl ligand failed.
SYNTHESIS OF ALLYL-TRANSITION METAL COMPLEXES BY PHASE TRANSFER CATALYZED REACTIONS OF METAL CARBONYL HALIDES. III. CONSIDERATIONS OF THE MECHANISMS
Gibson, Dorothy H.,Hsu, Wen-Liang,Ahmed, Fahim U.
, p. 379 - 401 (2007/10/02)
Mechanisms are proposed for the hydroxide ion-initiated reactions of metal carbonyl halides which lead to allyl-transition metal complexes under phase transfer conditions.Evidence is presented for intermediate anionic metallocarboxylic acids in reactions leading to η3-allyl products of molybdenum, iron, ruthenium and magnanese, whereas η1 complexes are shown to result from halide displacement reactions in which simple metal carbonyl anions are generated.In some cases phosphorus-containing ligands inhibit the hydroxide-promoted reactions of metal carbonyl halideswith allyl bromide; a rationale involving decreased acidity of the carbonyl ligands is presented. syntheses of η3-C3H5Mn(CO)3P(OCH3)3 and η3-C3H5Mn(CO)22 by phase transfer catalysis are also described.
REACTIONS OF 1-3-η-ALLYL-MANGANESE AND -RHENIUM TETRACARBONYLS WITH PHOSPHINES, PHOSPHITES, AND TRIPHENYLARSINE. THE CRYSTAL AND MOLECULAR STRUCTURE OF 1-3-η-ALLYLDICARBONYLBIS(TRIMETHYL PHOSPHITE)MANGANESE(I)
Brisdon, Brian J.,Edwards, Dennis A.,White, James W.,Drew, Michael G.B.
, p. 2129 - 2137 (2007/10/02)
The complexes n3, or PMePh2; M=Re, L=PPh3> and have been prepared from using thermal or photolytic methods.Taking the allyl group as bidentate, the complexes are considered to possess pseudo-octahedral stuctures, the carbonyl ligands being facial in the tricarbonyls and cis in the dicarbonyls.The 1H NMR spectra are characteristic of η3-allyl species and show strong 1H-31P coupling.The mass spectra of the complexes have also been obtained and fragmentation pathway suggested mainly on the basis of observed metastable peaks.Crystals of are monoclinic with a=18.618(11), b=9.218(7), c=10.607(11), β=102.1(1) deg, Z=4, and space group P21/a. 1 742 Independent reflections above background have been collected on a diffractometer and refined to R 0.059.The metal atom has a distorted octahedral environment, being bonded to two mutually trans phosphorus atoms, two cis carbonyls , and an allyl group .
