14516-54-2Relevant articles and documents
Acceleration of the methyl migration reaction with proton acids
Butts, Susan Beda,Richmond, Thomas G.,Shriver, Duward F.
, p. 278 - 280 (1981)
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Multi-step and multi-component organometallic synthesis in one pot using orthogonal mechanochemical reactions
Hernandez, Jose G.,Butler, Ian S.,Friscic, Tomislav
, p. 3576 - 3582 (2014/08/18)
We demonstrate that the mechanochemical strategies for oxidative addition and ligand substitution on organometallic centers can be mutually orthogonal, permitting the rational design of multi-component mechanochemical reaction procedures for assembling complex or solution-sensitive organometallic species from three, four or even five components in one pot. The herein established synthetic procedures represent a new level of complexity in mechanochemical reactions by milling and are the first to combine redox and ligand substitution reactions into mechanochemical strategies for either one-pot sequential ( telescoping ) or one-pot multi-component syntheses. This ability to combine mechanochemical transformations has enabled the solvent-free, room-temperature syntheses of relatively complex organometallics directly for simple zerovalent metal carbonyls as the simplest precursors. In particular, we demonstrate the efficiency of mechanochemical oxidative addition by targeting selected pentacarbonyl halides (fluoride, chloride, bromide, iodide) of rhenium(i) and manganese(i), and illustrate the potential of multi-step organometallic mechanochemistry in the syntheses of selected fac-tricarbonyl complexes of these metals.
Metal-metal bond cleavage of carbene complexes by halogens: The crystal and molecular structures of ax-[Mn2(CO)9{C(OEt)2-thienyl}], [Mn(CO)4(I){C(OEt)2-thienyl}] and eq-[Mn2(CO) 9{C(NH2)2-thienyl}]
Lotz, Simon,Landman, Marilé,Bezuidenhout, Daniela I.,Olivier, Andrew J.,Liles, David C.,Van Rooyen, Petrus H.
, p. 5929 - 5937 (2007/10/03)
The metal-metal bond in [M2(CO)9{C(OEt)R}] (M = Mn (1), Re (2), R = 2-thienyl (a), 2-bithienyl (b)) is readily cleaved with halogens to afford cis-[M(CO)4(X){C(OEt)R}] (M = Mn (3), X = I; M = Re (4), X = Br). In the binuclear manganese complex, the carbene ligand is found in an axial position due to steric reasons, whereas the electronically favoured equatorial position is found for the carbene ligands in the corresponding rhenium complexes and in [Mn2(CO)9{C(NH 2)thienyl}] (5a), containing a sterically less demanding NH 2-substituent.
Photochemistry and Emission of the Dinuclear Complexes (CO)5MnRe(CO)3(L) (L = 2,2'-Bipyrimidine, 2,3-Bis(2-pyridyl)pyrazine) and Bridged Trinuclear Complexes (CO)5MnRe(CO)3(L)Re(Br)(CO)3 and (CO)5MnRe(CO)3(BPYM)W(CO)4: Effect of the Remote Metal Center on the Photodissociation of the ...
Outersterp, J. W. M. van,Stufkens, D. J.,Vlcek, A. Jr.
, p. 5183 - 5194 (2008/10/08)
Photochemical and emission properties of the dinuclear (CO)5MnRe(CO)3(L) and trinuclear (CO)5MnRe(CO)3(L)Re(Br)(CO)3 and (CO)5MnRe(CO)3(BPYM)W(CO)4 complexes (L = 2,2'-bipyrimidine (BPYM), 2,3-bis(2-pyridyl)pyrazine(DPP)) are described. All these compounds undergo photochemical homolysis of the Mn-Re bond upon excitation into their MLCT absorption band(s) in the visible spectral region. Mn(Cl)(CO)5 and Re(Cl)(CO)3(L) or Re(Cl)(CO)3(L)Re(Br)(CO)3 are formed in chlorinated solvents (CH2Cl2, CCl4) from the former two types of complexes, respectively. In THF, photolysis produces Mn2(CO)10, together with [Re(CO)3(L)].bul., [Re(CO)3(L)Re(Br)(CO)3].bul., or [Re(CO)3(BPYM)W(CO)4].bul. radicals, respectively, which presumably contain also a coordinated THF molecule. Photoreactions of the dinuclear complexes occur with high quantum yields (0.36 for BPYM and 0.54 for DPP), which are independent of the temperature and of the excitation wavelength. The attachment of the Re(Br)(CO)3 group to the potentially bridging ligand L in (CO)5MnRe(CO)3(L) to form the L-bridged trinuclear species strongly influences the excited state dynamics involved in the photochemistry. Thus, the photochemical quantum yields of the trinuclear complexes are both temperature and excitation wavelength dependent. The apparent activation energy, together with the overall quantum yield, decreases upon changing the excitation from the high- to the low-energy MLCT absorption band. The Mn-Re bond homolysis is about 6 times more efficient for bridging DPP than for bridging BPYM. The dinuclear complexes exhibit, in a 2-MeTHF glass at 80 K, an emission from thermally unequilibrated states, whereas double emission, extending into the near-IR spectral region, was observed for (CO)5MnRe(CO)3(DPP)Re(Br)(CO)3. Its BPYM analogue is nonemissive. To account for this complex photobehavior, an excited state diagram and a qualitative dynamics model are proposed. The reaction is assumed to occur from a (3)σπ(*) state that is nonradiatively populated from the higher MLCT state(s). The main effects of the attachment of the Re(Br)(CO)3 group, which is responsible for the changed photochemical behavior, are the profound stabilization of the π(*) LUMO of the bridging ligand L and the introduction of another MLCT excited state into the trinuclear molecule.
