Reactions of manganese,rhodium, and iron allyl complexes with organometallic nucleophiles

Conclusions The reaction of cationic allyl complexes of manganese, rhodium, and iron with organometallic nucleophiles may proceed by three pathways: 1) addition of the nucleophile, 2) transallylation, and 3) reduction of the cationic complex.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2606–2609, November, 1987.     

A comparative study of high-spin manganese and iron complexes

Different metal complexes of the general form M(OH) _n (H₂O)_{6– n} have been studied for manganese and iron. Oxidation states considered for manganese are Mn(III), Mn(IV) and Mn(V) and for iron Fe(II), Fe(III) and Fe(IV). Oxygen containing ligands are used throughout with varying numbers of hydroxyl and water ligands. Some metal-oxo and some charged complexes were also studied. Large Jahn-Teller distortions were found for the Mn(III) and Fe(IV) complexes. Consequences of these distortions are that water ligands have to be placed along the weak JT-axis and that five-coordination by a loss of one of these water ligands is quite competitive with six-coordination in particular for manganese. For Fe(II) and Fe(III) lower coordinations than six are preferred due to the presence of two repulsive e _g electrons. For the metal-oxo complexes five-coordination is also preferred due to the strong trans effect from the oxo ligand. All complexes studied have high-spin ground states. An interesting effect is that the spin is much more delocalized on the ligands for the iron complexes than for the manganese complexes. This effect, which is chemically important for certain iron enzymes, is rationalized by the large number of 3d electrons on iron. For manganese with only five 3d electrons no spin delocalization is needed to obtain the proper high-spin states. Received: 4 February 1997 / Accepted: 24 February 1997     

Accurate redox potentials of mononuclear iron, manganese, and nickel model complexes*

Density functional theory (DFT) was combined with solution of the Poisson equation for continuum dielectric media to compute accurate redox potentials for several mononuclear transition metal complexes (TMCs) involving iron, manganese, and nickel. Progress was achieved by altering the B3LYP DFT functional (B4(XQ3)LYP-approach) and supplementing it with an empirical correction term G(X) having three additional adjustable parameters, which is applied after the quantum-chemical DFT computations. This method was used to compute 58 redox potentials of 48 different TMCs involving different pairs of redox states solvated in both protic and aprotic solvents. For the 58 redox potentials the root mean square deviation (RMSD) from experimental values is 65 mV. The reliability of the present approach is also supported by the observation that the energetic order of the spin multiplicities of the electronic ground states is fulfilled for all studied TMCs, if the influence from the solvent is considered as well.     

Dinuclear trivalent chromium,manganese, iron and cobalt complexes bridged by aromatic diamines

Summary Trivalent chromium, manganese, iron and cobalt salts react withm-phenylenediamine and acetylacetone to give complexes of the type [M(C₁₆H₁₈N₂O₂)X]: X = Cl, Br, NO₃ or NCS for M = chromium(III) and iron(III); X = Cl, Br, OAc or NCS for manganese(III); and X = OH for cobalt(III). Conductance measurements show the complexes to be nonelectrolytes. Molecular weights determined cryoscopically, show the iron complexes to be dinuclear. Magnetic measurements above 85 K reveal the presence of slight antiferromagnetic interactions. The complexes are dimeric five-coordinate square-pyramidal withm-phenylenediamine residues acting as bridges. The electronic spectra are interpreted in terms of the Normalised Spherical Harmonic Hamiltonian Theory and the DT/DQ values which indicate that chromium complexes are slightly distorted, whereas those of manganese are severely distorted.     

Synthesis of allyl complexes of iron,manganese and molybdenum by phase transfer catalysis

Synthetic methods are described for the convenient and efficient preparation of σ- and π-allyl complexes of iron, manganese and molybdenum from metal carbonyl halides and allyl halides in phase transfer catalyzed reactions.     

Reactions of hydridosilacyclobutanes with low-valent complexes of iron or platinum

Unstable transition metal compounds formed from hydridosilacyclobutanes are described: 1-methyl-1-silacyclobutane reacts with nonacarbonyldiiron to give the complexes [Fe(CO)₄(H){$\text{Si(Me)CH}{}_2\text{CH}{}_2\text{C}$H₂}] and [$\text{Fe{CH}{}_2\text{CH}{}_2\text{CH}{}_2\text{Si}$(H)Me}(CO)₄], and with bis(triphenylphosphine)(ethylene)platinum(0) to give [Pt(H)(PPh₃)₂{$\text{Si(Me)CH}{}_2\text{CH}{}_2\text{C}$H₂}].     

High-nuclearity manganese and iron complexes with the anionic ligand methyl salicylimidate

The three novel clusters [Mn6O4(OMe)2(OAc)4(Mesalim)4] (3), [Mn8O2(OH)2(OMe)12(OAc)2(Mesalim)4] (4), and [Fe10O4(OMe)14Cl2(Mesalim)6] (5) have been synthesized from a simple bidentate ligand HMesalim (HMesalim = methyl salicylimidate). Starting from the mononuclear complex [Mn(Mesalim)2(OAc)(MeOH)].MeOH (1), either the hexanuclear complex 3 or the octanuclear complex 4 is obtained after recrystallization, depending upon the reaction conditions and solvents used. Similarly, starting from the purple-colored mononuclear complex [Fe(Mesalim)2Cl] (2), the orange-colored decanuclear iron(III) cluster 5 has been obtained upon recrystallization from methanol. Complex 3, which could also be prepared directly from manganese acetate and the ligand, has a face-sharing double-cubane [Mn6O6] core, unique in transition metal chemistry. Compounds 4 and 5 are composed of [M3O4] partial cubanes. All complexes belong to a class of oxo-bridged cubic close-packed molecular clusters resembling the metal oxide/hydroxide ores. Complex 4 exhibits intramolecular ferromagnetic interactions, as evidenced from dc magnetic susceptibility studies (1.8-300 K), resulting in a high-spin ground state, probably with S(T) = 8. Complex 4 displays single molecule magnet behavior as indicated by frequency and temperature dependences of its ac susceptibility. An Arrhenius plot gave relatively large experimental activation energy of 36.0 K. The magnetic properties of complexes 3 and 5 are dominated by antiferromagnetic interactions leading to zero-spin ground states.     

Paramagnetic shifts in complexes of N-vinylimidazole with manganese,iron, cobalt,nickel, and copper chlorides

The observed paramagnetic shifts and broadenings of the resonance lines in the PMR spectrum of N-vinylimidazole upon the addition of its complexes with manganese, iron, cobalt, nickel, and copper chlorides are compared.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 994–995, July, 1972.We thank Doctor of Chemical Sciences Yu. N. Molin for his assistance in carrying out this investigation.     

非血红素铁、锰配合物催化烯烃不对称环氧化反应研究进展

手性环氧化物是重要的有机反应中间体.金属氧化酶催化的氧化反应通常具有高效、高选择性、反应条件温和和绿色的特点,模拟其中的非血红素铁加氧酶设计合成一系列手性四氮铁锰配合物催化烯烃不对称环氧化反应成为获得高产率、高对映选择性的手性环氧化物的一个重要方法.本文综述了近年来非血红素手性四氮铁锰配合物催化烯烃不对称环氧化反应的研究进展及相应的机理研究.     

Heteroligand complexes of chromium,manganese, and iron with trans-dibenzoporphyrazine and two oxo ligands: DFT calculations

Russian Chemical Bulletin - The possibility of formation of heteroligand (6,6,6,6)-macrotetracyclic chelate complexes of 3d-elements (M = Cr, Mn, Fe) with trans-dibenzoporphyrazine as the...     

Osmium,iridium and platinum pyridine complexes

Summary The syntheses, reactivity, physicochemical properties and applications of osmium, iridium and platinum complexes of pyridines are described.     

Preparation and characterisation of palladium, platinum and manganese di(organo)carbene complexes from quinolinone and quinolinium precursors

A series of palladium, platinum and manganese di(organo)carbene complexes have been prepared from 4-chloro-N-methylquinolinone by processes that involve alkylation before or after attachment to the metal unit; the nucleophilic heteroatoms are separated from the C-donor atom by three bonds.     

Dinuclear ruthenium and iron complexes containing palladium and platinum with tri-tert-butylphosphine ligands: synthesis, structures, and bonding

The reaction of Pd(PBu(t)(3))(2) with Ru(CO)(5) yielded the dipalladium-diruthenium cluster complex Ru(2)(CO)(9)[Pd(PBu(t)(3))](2), 10. The reaction of Pt(PBu(t)(3))(2) with Ru(CO)(5) at room temperature afforded the diplatinum-diruthenium cluster complex Ru(2)(CO)(9)[Pt(PBu(t)(3))](2), 12, and the monoplatinum-diruthenium cluster PtRu(2)(CO)(9)(PBu(t)(3)), 11. All three complexes contain a diruthenium group with bridging Pd(PBu(t)(3)) or Pt(PBu(t)(3)) groups. Compound 11 can be converted to 12 by reaction with an additional quantity of Pt(PBu(t)(3))(2). The reaction of 12 with hydrogen at 68 degrees C yielded the dihydrido complex Pt(2)Ru(2)(CO)(8)(PBu(t)(3))(2)(micro-H)(2), 13. This complex contains a Ru(2)Pt(2) cluster with hydride ligands bridging two of the Ru-Pt bonds. The reaction of Fe(2)(CO)(9) with Pt(PBu(t)(3))(2) yielded the platinum-diiron cluster complex PtFe(2)(CO)(9)(PBu(t)(3)), 14, which is analogous to 11. All new complexes were characterized crystallographically. Molecular orbital calculations of 10 reveal an unusual delocalized metal-metal bonding system involving the Pd(PBu(t)(3)) groups and the Ru(2)(CO)(9) group.     

Halo-carbonyl complexes of palladium,platinum and gold

In this review we summarize some recent literature data concerning synthetic procedures, properties, structure, reactivity and applications of halo-carbonyl complexes of palladium, platinum and gold, taking into consideration that the organometallic chemistry of these metals, with a particular attention to the halo-carbonyls, has been reviewed 20 years ago [F. Calderazzo, J. Organomet. Chem. 400 (1990) 303]. A brief overview of the early studies is provided.     

Formation of cationic peptide radicals by gas-phase redox reactions with trivalent chromium, manganese, iron, and cobalt complexes

The collision-induced dissociation (CID) of a series of gas-phase complexes [M(III)(salen)(P)](+) [where M = Cr, Mn, Fe, and Co; P = hexapeptides YGGFLR, WGGFLR, and GGGFLR; and salen = N,N'-ethylenebis(salicylideneaminato)] has been examined with respect to the ability of the complexes to form the corresponding cationic peptide radical ions, P(+)(*), by homolytic cleavage of the metal peptide bond. This is the first example of the use of gas-phase ternary metal peptide complexes to produce the corresponding cationic peptide radical for a metal other than copper(II). The fragmentation reactions competing with radical formation are highly dependent on the metal ion used. In addition, examination of modified complexes in which the periphery of the salen was substituted allowed evaluation of electronic effects on the CID process, presumably without significant change in the geometry surrounding the metal. This substitution demonstrates that the ligand can be used to tune the dissociation chemistry to favor radical formation and suppress unwanted further fragmentation of the peptide radical that is typically observed immediately following its dissociation from the complex.     

Reactions of N-phenyl-o-semiquinonediimine complexes of nickel and platinum with carbonyl-containing low-valence iron and rhenium compounds

The reactions of o-semiquinonediimine complexes M[o-(NH)(NPh)C₆H₄]₂ (M = Ni (1) or Pt (2)) with carbonyl-containing iron and rhenium compounds were studied. The reactions of complexes 1 or 2 with Fe(CO)₅ afforded the Fe₂(CO)₆[-(NH)(NPh)C₆H₄] complex (3) containing the bridging N-phenyl-o-phenylenediamide ligand in high yield. The reaction of the Re(CO)₂(NO)Cl₂(thf) complex with complex 2 gave rise to the unusual mononuclear rhenium(iii) complex, viz., Re(Ph)[-¹-o-(NH)(NHPh)C₆H₄](CO)(NO)Cl₂ (4), no changes in the geometry of N-phenyl-o-phenylenediamine bound to the Re(NO)(CO)₂Cl₂ fragment being observed. The reaction of complex 2 with the Re(CO)₅Cl complex, which has been preliminarily treated with silver triflate, afforded the heterometallic complex (CO)Pt[-N,N-o-(N)(NPh)C₆H₄]₂ReCl[(NH)(NPh)C₆H₄]. The structures of the resulting complexes were established by X-ray diffraction analysis.     

Pincer-like amido complexes of platinum, palladium, and nickel

The ligands bis(8-quinolinyl)amine (BQAH, 1), (2-pyridin-2-yl-ethyl)-(8-quinolinyl)amine (2-pyridin-2-yl-ethyl-QAH, 2), o-dimethylaminophenyl(8-quinolinyl)amine (o-(NMe2)Ph-QAH, 3), and 3,5-dimethylphenyl(8-quinolinyl)amine (3,5-Me2Ph-QAH, 4) have been prepared in high yield from aryl halide and amine precursors by palladium-catalyzed coupling reactions. Deprotonation of 1 with nBuLi in toluene affords the lithium amide complex [Li][BQA] (5), whose dimeric solid-state crystal structure is presented. Lithium amide 5 was transmetalated by TlOTf to afford the thallium(I) amido complex [Tl][BQA] (6). An X-ray structural study of 6 shows it to be a 1:1 complex of the BQA ligand and Tl. Entry into the group 10 chemistry of the parent ligand 1 was effected by both protolytic and metathetical strategies. Thus, the divalent chloride complexes (BQA)PtCl (7), (BQA)PdCl (8), and (BQA)NiCl (9) were prepared and fully characterized. An X-ray structural study for each of these three complexes shows them to be well-defined, square-planar complexes in which the auxiliary BQA ligand binds in a planar, eta(3)-fashion. For comparison, the reactivity of ligands 2-4 with (COD)PtCl2 was studied. While reaction with ligand 2 afforded an ill-defined product mixture, ligands 3 and 4 reacted with (COD)PtCl2 to generate the unusual alkyl complexes (o-(NMe2)Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (10) and (3,5-Me2Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (11), both of which have been structurally characterized.     

Formation,surface characterization,and electrocatalytic application of self-assembled monolayer films of tetra-substituted manganese,iron, and cobalt benzylthio phthalocyanine complexes

Molecular thin films of manganese (SAM-2), iron (SAM-3), and cobalt (SAM-4) phthalocyanine complexes, non-peripherally tetra-substituted with benzylmercapto, were formed on polycrystalline gold disc electrode by self-assembly technique. Surface characteristics of the films were interrogated by cyclic voltammetry. Significant passivation of voltammetry processes associated with bare gold surface (gold oxidation and underpotential deposition of copper) confirmed formation of the films. Electrocatalytic property of the films was evidenced from better voltammetry responses (less positive oxidation potential and better current signal) of the insecticide, carbofuran, on these films, relative to that on bare gold electrode. In terms of less positive oxidation potential, the FePc derivative (3) gave the best response, while the best current signal was observed on SAM-2-modified gold electrode. The average heterogeneous rate constant, k, for the oxidation of carbofuran was 3.6 × 10⁻² cm s⁻¹ on the SAM film with the best current signal (SAM-2).