14219-83-1Relevant academic research and scientific papers
Rates of halogen atom transfer to manganese carbonyl radicals
Herrick, Richard S.,Herrinton, Thomas R.,Walker, Howard W.,Brown, Theodore L.
, p. 42 - 45 (1985)
Flash photogeneration of Mn(CO)4L· radicals (L = CO, L) from 1,2-diax-Mn2(CO)8L2 in the presence of organic halides, or physical mixing of Mn(CO)3L2· (L = PR3) and organic halide solutions, produces Mn(CO)5-yLyX as the only product. Bimolecular atom transfer rate constants, kT, were measured for several radical/halide pairs by monitoring the decay of the visible or infrared absorbance of the radical. The rate constants vary over a range of 1010. Both the phosphine and organic halide affect the magnitude of kT. The rate of halogen atom transfer is accelerated by increased electron density at the metal center and is impeded by phosphine ligand bulk, as measured by the cone angle. The rate constants for reaction of CCl4 with Mn(CO)3[P(i-Bu)3]2 or Mn(CO)3[P(i-Pr)3]2 are smaller than for reaction with Mn(CO)4P(Z-Bu)3 or Mn(CO)4P(i-Pr)3, respectively. For a given halogen X, the rate constant is faster for C-X bonds of lower bond dissociation energy.
Photochemistry of organometallic halide complexes. Mechanisms for the formation of ionic products
Pan, Xiong,Philbin, Cecelia E.,Castellani, Michael P.,Tyler, David R.
, p. 671 - 676 (2008/10/08)
The photochemical reactions of the Mn(CO)5X (X = Cl, Br, I), CpMo(CO)3X (X = Cl, I), and CpFe(CO)2I complexes with various ligands were investigated with an emphasis on determining how ionic products form in these reactions. Two pathways account for the formation of ionic products: (1) M-X heterolysis and (2) metal-metal-bonded dimer formation followed by subsequent disproportionation. The metal-metal-bonded dimer may form via a secondary photolysis of a M-CO-loss photoproduct, via M-X heterolysis, or via a minor M-X homolysis pathway, followed by coupling of two metal radicals. CpMo(CO)3X reacts photochemically with a variety of ligands to give substitution products, but ionic products form only with pyridine and DMSO. With pyridine, the following sequence of reactions was found to yield ionic products: (1) CpMo(CO)3Cl →hν CpMo(CO)3 + Cl; (2) 2CpMo(CO)3 → Cp2Mo2(CO)6; (3) Cp2Mo2(CO)6 →hν CpMo(CO)3- + CpMo(CO)3py+. (Reaction 3 is the photochemical disproportionation of Cp2Mo2(CO)6 described previously by us.) The CpMo(CO)3X complexes are the only halides studied for which some M-X homolysis occurs; however, homolysis of the Mo-X bond is very inefficient: Φ = 9 × 10-4. For CpMo(CO)3X in DMSO, the only ionic product is CpMo(CO)2(DMSO)2+, formed by the following route: CpMo(CO)3Cl + DMSO →hν CpMo(CO)2(DMSO)Cl →hν CpMo(CO)2DMSO+ + Cl- → CpMo(CO)2(DMSO)2+. Ionic products form in the photochemical reactions of Mn(CO)5X complexes via the following route involving initial Mn-CO bond dissociation: Mn(CO)5X →hν Mn2(CO)8X2 →hν MnX2 + 3CO + 1/2 Mn2(CO)10. Photochemical disproportionation of the Mn2(CO)10 complex then occurs. Ionic products also form in the photochemical reactions of the CpFe(CO)2I complex via the intermediate formation of the metal-metal-bonded dimer, followed by disproportionation of this species. In this case, however, the dimer is formed by initial heterolysis of the Fe-I bond (CpFe(CO)2I →hν CpFe(CO)2+ + I-) followed by the sequence of reactions in Scheme II.
Homolytic Fission and Scrambling Reactions of Mn2(CO)8(PCy3)2 (Cy = cyclohexyl) and Mn2(CO)8(PPh3)2
Poe, Anthony,Sekhar, Chandra
, p. 566 - 567 (2007/10/02)
The complexes Mn2(CO)8L2 (L=PCy3 and PPh3) (Cy=cyclohexyl) both react with 1,1,2,2-tetrachloroethane to form ClMn(CO)4L at rates which conform with initial homolytic fission of the Mn-Mn bond and this mechanistic assignment is confirmed by the occurence o
