Patricia A. Goodson

Binuclear oxo-bridged iron(III) complexes of N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine (bispicen) and related ligands

Abstract The syntheses and characterization of a series of binuclear iron(III) complexes of the ligands N,N′-bis(2- pyridylmethyl)ethane-1,2-diamine (bispicen), C14H18N4, N,N′-bis(2-pyridylmethyl)propane-1,3-diamine (bispictn), C15H20N4, and N,N′-bis(2-pyridylmethyl)-N,N′-bis(methyl)-1,2-ethanediamine, C16H22N4, are described. The μ- oxo,μ-carbonatodiiron(III) complex {[(bispictn)Fe]2(μ-O)(μ-CO3)}(ClO4)2·3H2O C31H46Cl2Fe2N8O15 (1) crystatlizes in space group P 1 of the triclinic system with two binuclear species in a cell of dimensions a=12.552(3), b=12.980(3), c=15.016(3) A, α=88.49(3), β=68.57(3), γ=64.56(3)°. The tetradentate ligand binds the iron center in cis-β fashion. The structure has been refined to a final R factor of 0.0531 based on 2624 observed independent reflections. The complex contains a bent FeOFe unit with a bridging FeOFe angle of 129.7(3)° and associated average FeO and Fe···Fe separations of 1.803(7) and 3.264(2) A, respectively. The FeO (carbonato) distances are 1.960(5) and 1.968(5) A. The complex {[(bispicMe2en)Fe]2(μ-O)(μ-CO3)}(ClO4)2·2H2O, C33H48Cl2Fe2N8O14 (2) crystallizes in space group C2/c of the monoclinic system with eight binuclear species in a cell of dimensions a=19.580(4), b=13.442(3), c=32.727(7) A, β=94.07(3)°. The structure has been refined to a final R factor of 0.0634 based on 3279 observed independent reflections. The ligand binds the iron centers in cis-α fashion. The structure of the complex cation contains a bent FeOFe unit with a bridging FeOFe angle of 125.5(3)° and associated average FeO and Fe···Fe separations of 1.810(18) and 3.220(2) A, respectively. The FeO (carbonato) distances are 1.930(6) and 1.925(7) A. The novel μ-oxo,μ-sulfatodiiron(III) complex {[(bispicMe2en)Fe]2(μ-O)(μ-SO4)}(ClO4)2·2H2O, C32H48Cl2Fe2N8O15S (4) crystallizes in space group Pbca of the orthorhombic system with eight binuclear species in a cell of dimensions a=16.049(3), b=16.875(3), c=31.325(6) A. The structure has been refined to a final R factor of 0.0682 based on 1776 observed independent reflections. The ligand binds the iron centers in cis-α fashion. The structure of the complex cation contains a bent FeOFe unit with a bridging FeOFe angle of 132.4(5)° and associated average FeO and Fe···Fe separations of 1.806(4) and 3.306(2) A, respectively. The FeO (sulfato) distances are 1.980(11) and 1.981(11) A. Cyclic voltammograms of the complexes reveal an irreversible reduction at c. −0.70 V versus Ag/AgCl reference electrode for 1, 3 and 4 and a quasi-reversible reduction for 2 at −0.585 V corresponding to the Fe2(III/III) ↔ Fe2(II/III) redox process.

Syntheses and characterization of binuclear manganese(III,IV) and (IV,IV) complexes with 1,4,7,10-tetraazacyclododecane (cyclen)

Abstract The synthesis and characterization of di-μ-oxodimanganese(III,IV) and (IV, IV) complexes employing the tetradentate ligand 1,4,7,10-tetraazacyclododecane (cyclen) are reported. The crystal structure of the Mn(III,IV) complex, di-μ-oxo-bis(1,4,7,10-tetraazacyclododecane)dimanganese(III,IV) chloride lithium chloride pentahydrate, [(cyclen)Mn(III)O 2 Mn(IV)(cyclen)]Cl 3 ·LiCl·5H 2 O( 1a ), has been established by three dimensional X-ray diffraction techniques. The complex, of formula Mn 2 C 16 H 50 N 8 O 7 Cl 4 Li, crystallizes in the monoclinic space group C2/c with four molecules in a cell of dimensions a =20.284(4), b =10.576(2), c =15.345(2) A and β=105.70(1)°. The structure was solved by direct methods and refined by least-squares techniques to a final agreement factor of 0.0344 based on 3445 observed independent intensities. The dimer has a crystallographic inversion center in the middle, which is due to a static disorder in the crystals. The Mn-Mn distance in the complex is 2.694(1) A and the bridging Mn-O-Mn angle is 95.7(1)°. The magnetic properties of the III/IV complex are consistent with a doublet ground state, the observed J value of -138(2) cm −1 for la and -156.5(5) cm −1 for the corresponding perchlorate salt being similar to those observed in other III/IV complexes. The Mn(IV,IV) complex has a singlet ground state, with J =-144.5(10) cm −1 The EPR spectrum of the III/IV complex exhibits the commonly-occurring sixteen line pattern, with a significant degree of anisotropy. The EPR spectrum has been simulated by diagonalization of the energy matrix for the doublet state. The complex exhibits two quasi-reversible waves in the cyclic voltammogram, with redox potentials of 0.069 and 0.846 V (versus Ag/AgCI) for the III/III↔III/IV and III/ IV↔IV/IV couples, respectively. The electronic spectra of both the (III,IV) and (IV,IV) forms of the complex are similar to those of analogous complexes.

Synthesis and characterization of the mixed-valent complex ion di-μ-oxobis( 1,4,8,11-tetraazacyclotetradecane)dimanganese(III, IV), [(cyclam)MnO]23+

Abstract The synthesis and characterization of several salts of the mixed-valence binuclear cation [(cyclam)MnO]23+, where cyclam is 1,4,8,11-tetraazacyclotetradecane, are reported. The bromide salt, [(cyclam)MnO]2Br3·4H2O, crystallizes in the monoclinic space group P21/n with two molecules in a cell of dimensions a = 9.903(3), b = 11.565(3), c = 14.927(4) A, β = 107.87(2)° at −100 °C. Consequently, the two manganese centers are crystallographically equivalent. An analysis of the anisotropic displacement parameters (Uij), coupled with evidence from other experiments, demonstrates a static disorder in the crystals between chemically inequivalent Mn(III) and Mn(IV) sites. The structure has been refined to a weighted R factor of 0.0378 based on 2368 independent intensities. The manganese-manganese separation in the dimer is 2.731(2) A. The dithionate salt crystallizes in the monoclinic space group P21/a with four molecules in a cell of dimensions a = 15.216(3), b = 11.716(4), c = 18.745(6) A, β = 92.49(2)° at −100 °C. The complex crystallizes with two independent centrosymmetric dimers in the cell, but again this is due to a static disorder in the crystals. Disorder about one of the dithionate ions fits a model in which some of the dithionate ion has been converted to thiosulfate. The Mn-Mn separations are 2.729(5) and 2.738(5) A. The EPR spectrum of the complex at 4 K shows the sixteen line pattern commonly observed in di-μ-oxodimanganese(III,IV) complexes. The magnetic susceptibility of the complex demonstrates that the complex has a doublet ground state, exhibiting antiferromagnetic coupling with 2J = −237 cm−1.

Synthesis, structure and ligand exchange reactions of Ru(TTP)(NO)(OMe)

Abstract A facile, novel preparation of the useful synthon Ru(TTP)(NO)(OMe) is reported and it has been characterized by a range of techniques, including single crystal X-ray diffraction. Subsequent methoxide substitution reactions led to the preparation in high yield and purity of a wide variety of new complexes including a mercaptide complex which is the first reported analogue of the diamagnetic nitrosyl adducts of the P-450 monooxygenases.

Structural and magnetic characterization of an adamantane-like complex ion of chromium(III) and 1,3,5-triaminocyclohexane, [Cr4(tach)4(OH)6]6+

Abstract The synthesis and characterization of a tetranuclear chromium(III) complex of the ligand 1,3,5-triaminocyclohexane, (tach), C6H15N3, are described. The complex [Cr4(tach)4(OH)6] (ClO4)n(CF3SO3)6−n, where n refines to approximately 3.57, has been isolated and its structure has been determined from three-dimensional crystallographic data. The complex crystallizes in space group P21/c of the monoclinic system with four tetranuclear species in a cell of dimensions a=22.365(4), b=12.581(3), c=22.508(5) A, β=101.75(3)°. The structure has been refined to a final R factor of 0.0737 based on 6023 observed independent reflections. Each chromium(III) center is pseudo-octahedrally bonded to the three nitrogen atoms of the ligand and to three hydroxo groups; each hydroxo group acts as a bridge between two chromium atoms. The complex adopts the adamantane structure in which all four chromium atoms are chemically equivalent, as are all six hydroxide groups. The six independent Cr···Cr separations in the tetramer are in the narrow range 3.660–3.685 A. The temperature dependence of the magnetic susceptibility of the complex is consistent with the observed structure, the tetranuclear complex exhibiting an antiferromagnetic interaction with a J value of 8.91(2) cm−1. A model is presented which makes it possible to compare the antiferromagnetic interaction in complexes containing different numbers of metal atoms.

Monomeric complexes of manganese(II) with tetradentate ligands: isolation of cis-diaquamanganese(II) and cis-dichloromanganese(II) species

The synthesis and characterization of the monomeric complexes cis -diaqua( N , N ′-bis(2-methylpyrazyl)ethane-1,2-diamine)manganese(II) perchlorate monohydrate ( 1 ), or cis -[Mn(bispyzen)- (H 2 O) 2 ](ClO 4 ) 2 ·H 2 O, and cis -dichloro( N , N -bis((6-methylpyrid-2-yl)methyl)- N -2-pyridylmethylamine) manganese(II) ( 2 ) are reported. The diaqua complex crystallizes in the monoclinic space group P 2 1 / c with four molecules in a cell of dimensions a =13.394(4), b =9.778(3), c =17.434(7) A, β=103.15(3)°. The structure has been refined to an R factor of 0.0485 based on 3857 independent intensities. The OMnO bond angle in the complex is 93.9(1)°, and the MnO bond lengths are 2.137(3) and 2.158(3) A. There is extensive hydrogen bonding in the crystals. The dichloro complex crystallizes in the monoclinic space group P 2 1 / n with four molecules in a cell of dimensions a =8.993(2), b =28.717(7), c =9.053(2) A. β=118.84(1)°. The structure has been refined to an R factor of 0.0370 based on 3276 independent intensities. The ClMnCl bond angle in the complex is 99.4(1)°, and the MnCl bond lengths are 2.402(1) and 2.467(1) A. The axial MnN bond lengths of 2.423(2) and 2.456(3) A are much longer than the equatorial MnN distances of 2.285(3) and 2.329(3) A; this observed elongation of the axial bonds is presumably due to the steric crowding caused by the presence of the 6-methyl groups on the axial pyridine rings. The dichloro complex shows a quasi-reversible redox wave at 0.80 V versus Ag/AgCl corresponding to the Mn(II)↔Mn(III) couple.

π-Coordination of ortho-benzoquinone: synthesis and structure of [{Ru2(η4-µ2-o-C6H4O2)(CO)4(AsPh3)}2] and [Ru2(η4-µ2-o-C6H4O2)(CO)4(µ2-I)I]

The coordination polymer prepared by treating [Ru3(CO)12] with catechol can be cleaved with either a Lewis base or iodine to give products containing η4-ortho-benzoquinone ligands, two of which, [{Ru2(η4-µ2-o-C6H4O2)(CO)4(AsPh3)}2] and [Ru2(η4-µ2-o-C6H4O2)(CO)4(µ2-I)I] are structurally characterized by X-ray diffraction.

Functional nickel thiosalen complexes: structure and solid-state packing of a transition metal-based surfactant

Abstract The complex NiBr2(2-C12H25SC6H4CHNCH2CH2NCHC6H4SC12H25-2) (1) was prepared from the ligand 2-C12H25SC6H4CHNCH2CH2NCHC6H4SC12H25-2 (3) and NiBr2. Paramagnetic 1 was characterized by combustion analyses, 1H and 13C NMR spectroscopy, Vis–NIR spectroscopy, measurement of its magnetic susceptibility, and single-crystal X-ray diffraction. The crystal structure of 1 features octahedral coordination of Ni(II) with axial bromides and fully extended interdigitated alkyl chains. There are significant differences between the solid state structures of 1 and NiBr2(2-C6H12SC6H4CHNCH2CH2NCHC6H4SC6H12-2) (2), a previously reported homologue.

Solid-state structure of calcium (±)-threo-9,10-dihydroxyoctadecan-1-sulfate

Abstract The solid-state structure of calcium (±)- threo -9,10-dihydroxyoctadecan- l -sulfate (1) was determined. Compound 1 crystallized in the centrosymmetric triclinic space group PT with two [C 8 H 17 CH(OH)CH(OH)(CH 2 ) 8 OSO 3 ] 2 -Ca(H 2 O) 2 formula units in a unit cell of dimensions a = 5.507 (2) A, b = 10.323 (3) A, c = 40.175 (12) A, α = 91.54 (2)°, β = 93.67 (2)°, γ = 98.33 (2)° and V = 2253.5 (12) A 3 . The crystal packing is characterized by a tail-to-tail bilayer structure. Intermolecular hydrogen bonding occurs among the vic -diol-substituted hydrocarbon chains. Each calcium ion is seven-coordinate, bonding to oxygens of five different sulfate groups and to oxygens of two water molecules.

Solid-state structure of 2-hydrazino-N-dodecyl(tetradecyl)-N,N-dimethyl-2-oxoethanaminium bromide

Abstract The solid state structures of single-chain surfactants 2-hydrazino-N-dodecyl-N.N-dimethyl-2-oxoethanaminium bromide (1a) and the N-tetradecyl homologue (1b) were determined. Compound la crystallized in the centrosymmetric triclinic space group P 1 −1 (Z = 2) in a unit cell of dimensions a = 5.996 (1) A , b = 8.490 (2) A , c = 20.797 (4) A , a = 95.96 (3)°, β = 94.83 (3)°, y = 99.11 (3)°, and V = 1034.2 (4) A 3 . The crystal packing is characterized by an interdigitated bilayer structure featuring London forces among the alkyl chains and electrostatic interactions and hydrogen bonding within the polar head group region. The alkyl chains pack in the T∥ mode, and the molecular and chain cross sections are 50.26 A2 (S) and 20.65 A2 (Σ) respectively. The structural characteristics of 1b are analogous to those of 1a.