16972-33-1Relevant articles and documents
Ionic and covalent mixed-metal complexes by reaction of transition metal M-H acids (M = Mo, Mn, Fe, Co) with [Ir(PMe3)4CH 3] or [Rh(PMe3)3CH3] and structurally related Rh-M and Ir-M heterobimetallics (M = Mn, Fe, Ru)
Dahlenburg, Lutz,Hache, Roland
, p. 77 - 85 (2003)
Treatment of [Ir(PMe3)4CH3] with equimolar quantities of the carbonyl hydrides [M(CO)nH] (M=Mn, Co; n=5, 4) or [CpM(CO)nH] (M=Mo, Fe; n=3, 2) resulted in clean protonation of the d8 substrate producing cis-[Ir(PMe 3)4(H)(CH3)][X], where X-=[Mn(CO) 5]- (1), [Co(CO)4]- (2), [CpMo(CO)3]- (3), and [CpFe(CO)2]- (4), respectively. Combination of [Rh(PMe3)3CH 3] with [Mn(CO)5H] furnished [(Me3P) 3Rh(μ-CO)2Mn(CO)3PMe3] (5), which was also isolated from the salt elimination reaction between [Rh(PMe 3)4]Cl and Na[Mn(CO)5]. [(Me3P) 2Rh(μ-CO)2Fe(PMe3)Cp] (6), [(Me 3P)3Ir(μ-CO)2Fe(PMe3)Cp] (7), and [(Me3P)3Ir(μ-CO)2Ru(PMe3)Cp] (8) were obtained similarly by reacting [Rh(PMe3)4]Cl or [Ir(PMe3)4]Cl with the potassium salts K[CpM(CO) 2] (M=Fe, Ru). The crystal structure analysis of 3 demonstrates that in the solid state the hexacoordinate [Ir(PMe3)4(H) (CH3)]+ cation and its [CpMo(CO)3]- counterion exist as well-separated ion pairs. The structures of 5-8 comprise (Me3P)nRh (n=3, 2) or (Me3P)3Ir groups attached to Mn(CO)3PMe3 or M(PMe3)Cp fragments (M=Fe, Ru) by doubly carbonyl-bridged metal-metal bonds of normal length: Rh-Mn, 2.6695(14); Rh-Fe, 2.5748(6); Ir-Fe, 2.6470(7); Ir-Ru, 2.7348(14) A?.
Resurgence of Organomanganese(I) Chemistry. Bidentate Manganese(I) Phosphine-Phenol(ate) Complexes
Kadassery, Karthika J.,MacMillan, Samantha N.,Lacy, David C.
, p. 10527 - 10535 (2019)
As part of the United Nations 2019 celebration of the periodic table of elements, we are privileged to present our studies with the element manganese in this Forum Article series. Catalysis with organomanganese(I) complexes has recently emerged as an important area with the discovery that pincer manganese(I) complexes that can activate substrates through metal-ligand cooperative mechanisms are active (de)hydrogenation catalysts. However, this rapidly growing field faces several challenges, and we identify these in this Forum Article. Some of our efforts in addressing these challenges include using alternative precursors to Mn(CO)5Br to prepare manganese(I) dicarbonyl complexes, the latter of which is usually a component of active catalysts. Specifically, the synthesis of a new bidentate phosphine-phenol ligand along with its corresponding coordination chemistry of five new manganese(I) complexes is described. The complexes having two phenol-phenolate moieties interact with the secondary coordination sphere to enable facile loss of the bromido ligand and even one of the CO ligands to afford manganese(I) dicarbonyl centers.
Mechanism of the Hydrometalation ( Insertion ) and Stoichiometric Hydrogenation Reactions of Conjugated Dienes Effected by Manganese Pentacarbonyl Hydride: Processes Involving the Radical Pair Mechanism
Wassink, Berend,Thomas, Marian J.,Wright, Steven C.,Gillis, Daniel J.,Baird, Michael C.
, p. 1995 - 2002 (1987)
Manganese pentacarbonyl hydride (I) reacts with 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene to form predominantly the hydrometalated products of 1,4-addition of H-Mn(CO)5 to the dienes, i.e. R, R'=H, Me Monoolefins, the products of stoichiometric 1,2- and 1,4-addition of two hydrogen atoms to the dienes, are also formed as minor products, i.e. Hydrogenation is the predominant process with 1,3-cyclohexadiene.The hydrometalation reactions are first order in both I and diene, and the reaction rates are unaffected by added carbon monoxide (1 atm), while careful NMR monitoring of the early stages of the reactions under appropriate conditions reveals striking CIDNP polarizations for the 1H resonances of both the products of hydrometalation and of hydrogenation.The experimental evidence thus suggests that the reactions do not proceed via prior coordination of the olefin to the metal followed by conventional migratory insertion and reductive elimination processes but rather via hydrogen atom abstraction from I by the diene to give the corresponding radical pair.The latter can couple to give the hydrometalated compounds or diffuse apart to react with a second molecule of I to give Mn2(CO)10 and the monoolefins.For both types of products, the signs and, where measureable, the relative intensities of the CIDNP polarizations are completely consistent with the radical pair mechanism.
Mild reduction with silanes and reductive amination of levulinic acid using a simple manganese catalyst
Garcia, Juventino J.,Roa, Diego A.
, (2020/12/17)
A manganese-based catalytic system using the commercially available complex [Mn(CO)5Br] was studied for the selective reduction of levulinic acid (LA) to 2-methyl-tetrahydrofuran (MTHF). We further studied the production of pyrrolidines via its reductive amination using silanes (phenylsilane and tetramethyldisiloxane). The results showed high efficiency and selectivity for this reaction leading to high yields using mild reaction conditions.
Heterobimetallic complexes of rhodium dibenzotetramethylaza[14]annulene [(tmtaa)RH-M]: Formation, structures, and bond dissociation energetics
Imler, Gregory H.,Peters, Garvin M.,Zdilla, Michael J.,Wayland, Bradford B.
, p. 273 - 279 (2015/03/13)
A rhodium(II) dibenzotetramethylaza[14]annulene dimer ([(tmtaa)Rh]2) undergoes metathesis reactions with [CpCr(CO)3]2, [CpMo(CO)3]2, [CpFe(CO)2]2, [Co(CO)4]2, and [Mn(CO)5]2 to form (tmtaa)Rh-M complexes (M = CrCp(CO)3, MoCp(CO)3, FeCp(CO)2, Co(CO)4, or Mn(CO)5). Molecular structures were determined for (tmtaa)Rh-FeCp(CO)2, (tmtaa)Rh-Co(μ-CO)(CO)3, and (tmtaa)Rh-Mn(CO)5 by X-ray diffraction. Equilibrium constants measured for the metathesis reactions permit the estimation of several (tmtaa)Rh-M bond dissociation enthalpies (Rh-Cr = 19 kcal mol-1, Rh-Mo = 25 kcal mol-1, and Rh-Fe = 27 kcal mol-1). Reactivities of the bimetallic complexes with synthesis gas to form (tmtaa)Rh-C(O)H and M-H are surveyed.
