Naohide Matsumoto

Catalytic asymmetric epoxidation of unfunctionalized olefins using chiral (salen)manganese(III) complexes

Abstract Several kinds of chiral (salen)manganese(III) complexes ( 2 and 3 ) having chiral salicylaldehyde and chiral ethylenediamine moieties were prepared and used for catalytic asymmetric epoxidation of unfunctionalized olefins with iodosobenzene as a terminal oxidant. Catalysts 2 and 3 were found to show the characteristic substrate specificity for the enantiofacial selection of olefins, respectively. Furthermore, the addition of donor ligands such as pyridine N -oxide or 2-methylimidazole to the epoxidation reaction system was found to alter the enantioselectivity. As a result, the highest enantioselectivity for nonenzaymatic catalytic epoxidation was achieved for ( E )-1-phenylpropene (56% ee, with 2c in the presence of 2-methylimidazole), ( E )-stilbene (48% ee, with 3a ), and dihydronaphthalene (83% ee, with 3a in the presence of pyridine N -oxide).

Ferrimagnetic Mixed-Metal Assemblies {NBu4[MFe(ox)3]}x

Abstract Hetero-metal assemblies, (NBu4=tetra(n-butyl)ammonium ion; ox=oxalate ion; M(II)=Ni(1), Fe(2), Mn(3), Zn(4)) have been synthesized by the use of [Fe(ox)3]3- as the building block. 1 and 2 are ferrimagnets of TN=43 and 28 K, respectively. 3 is an antiferromagnet. 4 shows a paramagnetic behavior.

Crystal structure and magnetic property of the binuclear manganese(III) complex [Mn(L)H2O]2(ClO4)2(L N-(acetylaceto nylidene)-N′-(α-methylsalicylidene)-ethylenediamine)

Abstract The crystal structure and magnetic property of the title compound [Mn(L)H2O]2(ClO4)2 are described. The complex crystallizes in the triclinic space group P 1 with formula = MnClO7N2C15H20, a = 11.615(4), b = 11.955(4), c = 7.753(2) A, α = 104.65(2), β = 111.84(3), γ = 63.64(2)°, V = 890.5(6) A3 and Z = 2. The complex consists of a binuclear structure bridged by two phenoxo oxygen atoms O(1) and O(1)* of the quadridentate ligands in an out-of-plane mode, where the binuclear structure has a crystallographical center of symmetry, and the bond distances of MnMn* and MnO(1)* are 3.318(1) and 2.305(2) A, respectively. The magnetic susceptibility data (4.2–300 K) showed a maximum at 11 K and were closely reproduced by the spin-Hamiltonian H = 2JS1·S2 with J = −1.68 cm−1 and g = 2.01. The deviation of the observed values from the theoretical curve in the lower temperature region is due to the zerofield splitting term. The X-band ESR spectrum in frozen dichloromethane solution at 20 K showed a broad signal at 900 G and a multiline signal at 3300 G.

Synthesis and characterization of novel binuclear copper(II) and nickel(II) complexes with N,N′,N″,N‴-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) containing various anions. X-ray analyses of [Cu2F(tpmc)](ClO4)3·2CH3CN and [Cu2Cl(tpmc)](ClO4)3·H2O

Abstract Seven copper(II) and three nickel(II) complexes with N,N′,N″,N‴-tetrakis(2-pyridylmethyl)-1,4,8,11- tetraazacyclotetradecane(tpmc), [Cu2X(tpmc)](ClO4)3 (X=Cl, Br, I, N3, NO2), [Cu2Y2(tpmc)](ClO4)2 (Y=NCS, N3), [Ni2(tpmc)](ClO4)4 (orange and blue forms) and [Ni2Br2(tpmc)](ClO4)2 have been synthesized. The formation constants for the reaction [Cu2(tpmc)]4+ + X− ⇌ [Cu2X(tpmc)]3+ X=F, Cl, Br, I, NO2 were determined spectrophotometrically, and were revealed to be very high for the CuX binding in aqueous solution. X-ray analyses of [Cu2F(tpmc)](ClO4)3·2CH3CN and [Cu2Cl(tpmc)](ClO4)3·H2O showed halogeno bridged dinuclear structure. On the basis of the electronic spectra, IR spectra, stability constants and magnetic moments it is assumed that bromo, iodo, azido and nitrito complexes have similar structures to those of the fluoro and chloro complexes. The orange form of [Ni2(tpmc)](ClO4)4 was diamagnetic and its visible spectra was consistent with square-planar coordination. The blue form was paramagnetic (μ=2.96 BM/Ni), hence the nickel ions are five coordinated.

MACROCYCLIC HETERODINUCLEAR NIMN AND CUMN COMPLEXES : CRYSTAL STRUCTURE AND ELECTROCHEMICAL BEHAVIOUR

Dinuclear Ni(II)Mn(II) and Cu(II)Mn(II) complexes of the general formula [MMn(Lm,n)](ClO4)2 ((Lm,n)2−= (L2,3)2−, (L2,4)2−(L3,3)2−; M = Ni, Cu) are obtained as solvates, using the dinucleating macrocycles (Lm,n)2− (derived from the [2:1:1] condensation of 2,6-diformyl-4-methylphenol, NH2(CH2)mNH2 (m = 2–3) and NH2(CH2)nNH2 (n = 2−4). [NiMn(L2,3)](ClO4)2·2DMF crystallizes in the orthorhombic space group Pbca with a = 22.186(4), b = 22.855(3), c = 13.951(2) A, V= 7074(2) A3, and Z= 8. [NiMn(L2,4)](ClO4)2·2DMF crystallizes in the monoclinic space group P21/n with a = 15.330(4), b = 11.739(3), c = 20.829(5) A, β = 101.05(2)°, V= 3678(1) A3, and Z=4. In both complexes the Ni(II) and Mn(II) ions are bridged by two endogenous phenolic oxygens of the macrocycle, with the NiMn intermetallic separation of 3.145(2)A for the former and 3.111(3)A for the latter. In each complex the Ni(II) resides at the N202 site with the ethylene lateral chain and assumes a planar geometry. The Mn(II) at the N202 site with the trimethylene or tetramethylene lateral chain assumes a distorted six-coordinate geometry together with two DMF molecules. The M(II)Mn(II) (M  Ni, Cu) complexes are electrochemically converted to M(I)Mn(II) and M(II)Mn(III) complexes which are characterized by visible spectroscopy.

One-dimensional structures of manganese(II) complexes [MnII(hfac)2L] hfac = hexafluoroacetylacetonate anion; L = N-(4-pyridylmethyl)imidazole, trans-1,2-bis(4-pyridyl)ethylene, imidazole)

Abstract Bis(hexafluoroacetylacetonato)diaquamanganese(II) [Mn(hfac)2(H2O)2] reacts with N-(4-pyridylmethyl)imidazole (pyim), trans-1,2-bis(4-pyridyl)ethylene (bpye) and imidazole (Him) to give their adducts with three different kinds of one-dimensional structures [Mn(hfac)2(pyim)] (1), [Mn(hfac)2(bpye)] (2) and [Mn(hfac)2(Him)2] (3), respectively. Compound 1 crystallizes in the monoclinic space group P2 1 n with a = 9.696(3), b = 14.839(4), c = 17.076(3) A , β = 92.70(2)°, and assumes a one-dimensional structure running along the b-axis in which the adjacent molecules are related by a two-fold screw axis. Compound 2 crystallizes in the space group C2 c with a = 9.554(2), b = 16.476(2), c = 16.137(2) A , β = 96.97(2)°, and assumes a zigzag-chain structure. Compound 3 crystallizes in the space group P2 1 c with a = 7.526(3), b = 14.506(3), c = 10.394(2) A , β = 96.71(2)° and the one-dimensional structure of 3 is formed by a hydrogen bond between NH of imidazole and O of hfac.

SYNTHESIS, CHARACTERIZATION, STRUCTURE AND POSSIBLE CATALYTIC PROPERTIES OF CIS-OXALATO(1,4,8,11-TETRAAZACYCLOTETRADECANE)COBALT(III) NITRATE

Abstract A new complex of cobalt(III) with 1,4,8,11-tetraazacyclotetradecane (cyclam) and oxalato ion as a bidentate ligand was prepared and characterized by elemental analysis, IR, electronic and 1H NMR spectroscopy and cyclic voltammetry. X-Ray analysis has shown that this compound crystallizes in the orthorhombic system, space group Pccn, with a = 8.583(1), b = 12.854(2), c = 14.944(1)A, V = 1649.3(4) A3, Z = 4, R = 0.512, Rw = 0.545, and has a crystallographic two-fold rotation axis. The complex was identified as cis-oxalato(1,4,8,11-tetraazacyclotetradecane)cobalt(III) nitrate, [Co(ox)cyclam]NO3 (oxH2 = oxalic acid), and it can be described in terms of a cis octahedral geometry with a folded cyclam configuration around the cobalt atom with the oxalato ion occupying the remaining two sites. Cyclic voltammetric data suggest a large stability for this compound, as well as its possible catalytic effect on electrochemical CO2 reduction.

A tetrahedral zinc(II) complex of N-(R)-1-phenylethylsalicylideneimine. Structural and circular dichroism spectral investigations on stereoselectivity

The stereoselectivity of bis[N-(R)-1-phenylethylsalicylideneiminato]zinc(II) has been studied by means of single-crystal X-ray analysis and circular dichroism (c.d.) spectra. The complex crystallizes in space group P212121 with a= 17.738(4), b= 29.632(9), c= 9.968(2)A, and Z= 4. The unit cell is comprised of four units each containing two complex molecules (A and B). Each molecule adopts a nearly tetrahedral structure with two bidentate ligands; the dihedral angle defined by the two chelate rings is 81.7° for molecule A and 84.9° for molecule B. The absolute configuration along the pseudo-C2 axis is Λ for both molecules. Based on the X-ray analysis it is suggested that intramolecular non-covalent interactions between the chiral N-substituent and the adjacent chelate ring give rise to stereoselectivity and the Λ configuration around the metal ion. The c.d. couplet (+and – signs) induced at the azomethine π–π* transition at around 27 000 cm–1 is discussed with respect to the absolute configuration and in comparison with the spectra of related Schiff-base complexes.

Synthesis, structure, and magnetism of binuclear copper(II) complexes of pyrazole ligands with nitrogen-containing chelating arms. First example of di-µ-pyrazolato-dicopper(II,II) complexes

The preparation of new dinucleating pyrazole ligands, 3,5-bis[(2-diethylamino)ethylaminomethyl]pyrazole (HL1) and 3,5-bis[(3-dimethylamino)propylaminomethyl]pyrazole (HL2), has been accomplished. They afford binuclear copper(II) complexes of the formula [Cu2L2][BPh4]2(L = L1 or L2). The structure of [Cu2L12][BPh4]2 was determined by single-crystal X-ray analysis. It crystallizes in the triclinic space group P with a= 13.437(4), b= 15.192(5), c= 12.364(4)A, α= 116.38(3), β= 113.71(3), γ= 60.48(2)°, and Z= 1. The complex has a binuclear structure doubly bridged by the pyrazolate groups with the Cu ⋯ Cu separation 3.903(2)A. The configuration geometry of each copper is a square pyramid, whose basal plane is formed by the two pyrazolate nitrogens and the ‘articular’ nitrogens [Cu–N 1.906(3)–2.028(3)A] and the apical site by one of the ‘terminal’ nitrogens [Cu–N 2.496(5)A]. The other terminal nitrogen is free from co-ordination. Cryomagnetic investigations over the temperature range 100–300 K revealed a strong antiferromagnetic spin exchange in both complexes. The exchange integral (J) based on the Heisenberg model, was evaluated as – 214 cm–1 for [Cu2L12][BPh4]2 and –181 cm–1 for [Cu2L22][BPh4]2.

Syntheses, structures and magnetic properties of the tricyanoethenolate adducts of quadridentate Schiff base manganese(III) complexes

Manganese(III) complexes [Mn(L1)(NCO)] and [Mn(L2)(NCO)] (H2L1 = N,N′-ethylenebis(3-hydroxy-4-naphthylideneiminate), H2L2 = N,N′-(1,1,2,2-tetramethylethylene)bis(3-hydroxy-4-naphthylideneiminate)) react with tetracyanoethylene in a mixed solution of dichloromethane and acetonitrile to give the tricyanoethenolate adducts [Mn(L1)(TCEA)(H2O)] (1) and [Mn(L2)(TCEA)] (2) (TCEA = tricyanoethenolate, [(NC)2C=C(CN)O−]), respectively. Compound 1 crystallizes in the triclinic space group P1 with a = 10.612(5), b = 13.369(5), c = 9.981(6) A, α = 108.89(4), β = 110.70(4), γ = 77.22(4)°. The Mn(III) assumes an elongated square bipyramidal geometry, in which two apical sites are occupied by an oxygen atom of a water molecule with MnO(3) = 2.305(4) A and by a nitrogen atom of TCEA with MnN(3) = 2.390(4) A. The water oxygen is hydrogen bonded to a nitrogen atom of TCEA of the adjacent molecular unit with O(3)N(3)∗ = 3.081(6) A forming a one-dimensional chain structure of head-to-tail fashion. Compound 2 crystallizes in the monoclinic space group P21/c with a = 14.107(6), b = 12.750, c = 16.481(5) A, β = 103.64(3)°. Compound 2 has a binuclear structure of out-of-plane fashion, where the dimensions of the Mn2O2 core are MnMn∗ = 3.475(2) A and MO(1)∗ = 2.627(3) A. The Mn(III) assumes a distorted square bipyramidal geometry, in which two apical sites are occupied by the phenoxy oxygen atom of L2 and an oxygen atom of the TCEA anion with 2.163(3) A. The magnetic susceptibility measurements in the range 4.4–300 K showed that a weak intermolecular antiferromagnetic interaction or/and zero field splitting is operating for 1, while a intradimer ferromagnetic interaction is operating for 2.