Fe-P Bonds Research Articles

Light activated methylene blue degradation by magnetic Fe80PxC20-x (x = 0, 4, 7 and 13) glassy ribbons

The light activated Methylene Blue (MB) degradation performance and magnetic properties of the Fe80PxC20-x (x = 0, 4, 7 and 13) glassy ribbons are investigated in this work. The structure of the as-spun Fe80C20 ribbons is crystalline state while the as-spun Fe80PxC20-x (x = 4, 7 and 13) ribbons is amorphous state. Under dark condition, the degradation efficiency ηDark for MB decreases gradually with increasing P content (cP) in the ribbons, and the stability of Fe-P bonds is higher than Fe-C bonds in annealing Fe80P4C16 ribbons, indicating that Fe-P bonds release less Fe participating in the Fenton-like reaction; under visible light (VL), the ηVL of ribbons increases firstly and then decreases with increasing cP and the ribbon with x = 4 show the highest ηVL, which is consistent with the changing tendency of soft magnetic property of the present ribbons. This work provides a new insight in designing and applying the FePC amorphous alloys.

UJI EFEKTIVITAS KOMPOS KOTORAN SAPI DAN SEKAM PADI MENGGUNAKAN MIKROORGANISME LOKAL BATANG PISANG TERHADAP POPULASI BAKTERI PELARUT FOSFAT DAN PRODUKSI PAKCOY (Brassica rapa var. chinensis L.)

Management of agricultural land in Jabung District using inorganic fertilizers with high doses resulted in a decrease in soil quality, such as a low population of phosphate solubilizing bacteria that can release phosphate from Al-P and Fe-P bonds. Inceptisols in Jabung Subdistrict with low fertility still has the potential to cultivate pakcoy with the innovative application of cow manure and rice husk compost with banana stem MOL bioactivator as a source of bacterial culture and organic matter decomposers. This study was aimed to determine the effectiveness of the application of cow dung and rice husk compost on the population of phosphate solubilizing bacteria, the diversity of bacteria in dissolving phosphate based on the clear zone index, and the yield of pakcoy. This study used a randomized block design with six treatments and four replications. The results showed that cow dung and rice husk compost significantly increased the population of phosphate solubilizing bacteria by 27.7 × 106 CFU g-1, diversity of phosphate solubilizing bacteria based on the clear zone index as many as 23 isolates with the highest clear zone index 5,40 isolate code P52. The results also showed that the application of cow dung and rice husk compost significantly increased the wet weight by 15,520 kg ha-1 and the dry weight of pakcoy by 661.6 kg ha-1.

Interfacial Engineering and a Low-Crystalline Strategy for High-Performance Supercapacitor Negative Electrodes: Fe2P2O7 Nanoplates Anchored on N/P Co-doped Graphene Nanotubes.

Developing novel hybrid negative electrode materials with high specific capacity, rate capacitance, and long-term cycle stability is a key factor for pushing large-scale application of supercapacitors. However, construction of robust interfaces and low-crystalline active materials plays a crucial role in realizing the target. In this paper, a one-step phosphorization approach was employed to make low-crystalline Fe2P2O7 nanoplates closely bonded to N/P-co-doped graphene nanotubes (N/P-GNTs@b-Fe2P2O7) through interfacial chemical bonding. The N and P heteroatoms as substitutions for C in GNT skeletons can introduce rich electronic centers, which induces Fe2P2O7 to fix the surface of N/P-GNTs through Fe-N and Fe-P bonds as confirmed by the characterizations. Moreover, the low-crystalline active materials own a disordered internal structure and numerous defects, which not only endows with excellent conductivity but also provides many active sites for redox reactions. Benefiting from the synergistic effects, the prepared N/P-GNTs@b-Fe2P2O7 can not only deliver a high capacity of 257 mA h g-1 (927 F g-1) at 1 A g-1 but also present an excellent rate capability of 184 mA h g-1 (665 F g-1) at 50 A g-1 and outstanding cycle stability (∼90.6% capacity retention over 40,000 cycles). Furthermore, an asymmetric supercapacitor was assembled using the obtained N/P-GNTs@b-Fe2P2O7 as electrode materials, which can present the energy density as high as 83.3 W h kg-1 at 791 W kg-1 and long-term durability. Therefore, this strategy not only offers an effective pathway for achieving high-performance negative electrode materials but also lays a foundation for further industrialization.

Local Structure and Magnetism of LiFeSi0.01P0.99O4/C as a Cathode Material on Lithium-Ion Battery

The oxidation state and local structure of LiFeSi0.01P0.99O4/C composites as a cathode on lithium-ion battery were investigated by Fe K-edge X-ray Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). The LiFeSi0.01P0.99O4/C sample was prepared by solid-state reaction process. Based on the XANES analysis, the absorption of edge energy (E0) of the sample was 7124.92 eV. In addition, linear combination fitting (LCF) analysis of XANES confirmed the oxidation state of iron mixture of 2+ and 3+ as the effect of silicon doped in LiFePO4. The Fourier Transform (FT) of the Fe K-edge EXAFS fitting analysis showed that the nearest neighbors surrounding atom Fe were the main peak with high intensity that confirmed Fe-O bond; the second and third peak with lower intensity confirmed Fe-P and Fe-Fe bonds, respectively. In addition, the SQUID magnetometer result of LiFeSi0.01P0.99O4/C indicated the antiferromagnetic order temperature of LiFeSi0.01P0.99O4/C at ~51 K with the indication of the presence of impurity and structural distortion.

Novel iron (II) complexes of 1,5-diaza-3,7-diphosphacyclooctanes

New cationic octahedral bis-ligand iron (II) complexes of 1,5-diaza-3,7-diphosphacyclooctanes were synthesized as mixtures of two cis-isomers with different mutual arrangement of Fe–P-bonds and co-ligands which may be separated by a fractional crystallization.

Flexibility and Stability of Metal Coordination Macromolecules.

The effect of chain structure on flexibility and stability of macromolecules containing weak P-Fe metal coordination bonds is studied. Migration insertion polymerization (MIP) of FpCX Fp (1) and PR2 CY PR2 (2) (Fp: CpFe(CO)2 ; CX and CY : alkyl spacers; P: phosphine; R: phenyl or isopropyl) generates P(1/2), in which the P-Fe and Fe-P bonds with opposite bonding direction are alternatively arranged in the backbone. On the other hand, P(FpCX P) synthesized from AB-type monomers (FpCX P) has P-Fe bonds arranged in the same direction. P(1/2) is more rigid and stable than P(FpCX P), which is attributed to the chain conformation resulting from the P-Fe bonding direction. In addition, the longer spacers render P(1/2) relatively flexible; the phenyl substituents, as compared with the isopropyl groups, improves the rigidity, thermal, and solution stability of P(1/2). It is therefore possible to incorporate weak metal coordination bonds into macromolecules with improved stability and adjustable flexibility for material processing.

Isolation of a Mixed Valence Diiron Hydride: Evidence for a Spectator Hydride in Hydrogen Evolution Catalysis

The mixed-valence diiron hydrido complex (μ-H)Fe2(pdt)(CO)2(dppv)2 ([H1](0), where pdt =1,3-propanedithiolate and dppv = cis-1,2-C2H2(PPh2)2), was generated by reduction of the differous hydride [H1](+) using decamethylcobaltocene. Crystallographic analysis shows that [H1](0) retains the stereochemistry of its precursor, where one dppv ligand spans two basal sites and the other spans apical and basal positions. The Fe---Fe bond elongates to 2.80 from 2.66 Å, but the Fe-P bonds only change subtly. Although the Fe-H distances are indistinguishable in the precursor, they differ by 0.2 Å in [H1](0). The X-band electron paramagnetic resonance (EPR) spectrum reveals the presence of two stereoisomers, the one characterized crystallographically and a contribution of about 10% from a second symmetrical (sym) isomer wherein both dppv ligands occupy apical-basal sites. The unsymmetrical (unsym) arrangement of the dppv ligands is reflected in the values of A((31)P), which range from 31 MHz for the basal phosphines to 284 MHz for the apical phosphine. Density functional theory calculations were employed to rationalize the electronic structure of [H1](0) and to facilitate spectral simulation and assignment of EPR parameters including (1)H and (31)P hyperfine couplings. The EPR spectra of [H1](0) and [D1](0) demonstrate that the singly occupied molecular orbital is primarily localized on the Fe center with the longer bond to H, that is, Fe(II)-H···Fe(I). The coupling to the hydride is A((1)H) = 55 and 74 MHz for unsym- amd sym-[H1](0), respectively. Treatment of [H1](0) with H(+) gives 0.5 equiv of H2 and [H1](+). Reduction of D(+) affords D2, leaving the hydride ligand intact. These experiments demonstrate that the bridging hydride ligand in this complex is a spectator in the hydrogen evolution reaction.

Tris(acetonitrile-κN){2,6-bis[(diphenylphosphanyl)amino]-4-ethoxy-1,3,5-triazine-κ3P,N1,P′}iron(II) bis(tetrafluoridoborate) acetonitrile disolvate

In the title compound, [Fe(CH3CN)3(C29H27N5OP2)](BF4)2·2CH3CN, the FeII ion is octa­hedrally coordinated by a meridionally chelating tridentate pincer-type PNP ligand derived from 2,6-diamino-4-eth­oxy-1,3,5-triazine and by three acetonitrile mol­ecules. The four Fe—N bond lengths range from 1.9142 (12) to 1.9579 (11) Å, while the Fe—P bonds are 2.2452 (4) and 2.2506 (4) Å [P—Fe—P = 165.523 (14)°], consistent with FeII in a low-spin state. Unlike related Fe PNP complexes based on 2,6-diamino­pyridine, the BF4 anions are not hydrogen bonded to the two NH groups of the pincer ligand but show instead anion–π inter­actions with the triazine ring and acetonitrile mol­ecules in addition to ten C—H⋯F inter­actions. Most remarkable among these is an anion–π(triazine) inter­action with a short distance of 2.788 (2) Å between one F and the centroid of the π-acidic triazine ring. The corresponding shortest distance between this F atom and a triazine carbon atom is 2.750 (2) Å. The two NH groups of the pincer ligand donate N—H⋯N hydrogen bonds to the triazine N atom of a neighbouring complex and to an uncoordinated acetonitrile mol­ecule. This last mol­ecule is in a side-on head-to-tail association with the second uncoordinated acetonitrile at C⋯N distances of 3.467 (2) and 3.569 (2) Å. In contrast to several related compounds with diamino­pyridine- instead of diamino­triazine-based PNP ligands, the title crystal structure is remarkably well ordered. This suggests that the diamino­triazine moiety exerts notable crystal structure stabilizing effects.

Grain Boundary Embrittlement of Fe Induced by P Segregation: First-Principles Tensile Tests

The GB embrittlement mechanism of Fe enhanced by P segregation has been investigated by first-principles tensile tests because a P atom is a famous GB embrittler in Fe. The first-principles tensile tests have been performed on Fe with two P-segregated GBs, where P atoms are located at the different sites, and with a nonsegregated GB. The tensile strength and the strain to failure in the P-segregated GBs were lower than those in the nonsegegated GB. The first bond breaking occurred at the Fe-P bond owing to the covalent-like characteristics, although the charge densities were high at the Fe-P bonds even just before the bond breaking. This premature bond breaking of Fe-P was independent of the location of the P atom.

A Nonclassical Dihydrogen Adduct of S = 1/2 Fe(I)

We have exploited the capacity of the "(SiP(iPr)(3))Fe(I)" scaffold to accommodate additional axial ligands and characterized the mononuclear S = ½ H(2) adduct complex (SiP(iPr)(3))Fe(I)(H(2)). EPR and ENDOR data, in the context of X-ray structural results, revealed that this complex provides a highly unusual example of an open-shell metal complex that binds dihydrogen as a ligand. The H(2) ligand at 2 K dynamically reorients within the ligand-binding pocket, tunneling among the energy minima created by strong interactions with the three Fe-P bonds.

First-Principles Study on Enhanced Grain Boundary Embrittlement of Iron by Phosphorus Segregation

It is known that segregation of P atoms at grain boundaries (GB) enhances the intergranular embrittlement in Fe. In the present work, firstprinciples tensile tests have been performed on two bcc Fe cell models with a 3 ð111Þ=1⁄21 10 tilt GB: the cell model without P segregation at the GB (clean GB model) and the cell model with P segregation at the GB (P-segregated GB model). The tensile strength and the strain to failure in the P-segregated GB model were 6% and 13% lower than those in the clean GB model. The first bond breaking occurred at the Fe-P bond due to the covalent-like characteristics, although the charge densities were high at the Fe-P bonds. This premature bond breaking of Fe-P was independent of the location of the P atom. [doi:10.2320/matertrans.MBW201022]

Different response of the crystal structure to isoelectronic doping inBaFe2(As1−xPx)2and(Ba1−xSrx)Fe2As2

Superconductivity up to 30 K in charge neutrally doped ${\text{BaFe}}_{2}{({\text{As}}_{1\ensuremath{-}x}{\text{P}}_{x})}_{2}$ has been ascribed to chemical pressure caused by the shrinking unit cell. But the latter induces no superconductivity in $({\text{Ba}}_{1\ensuremath{-}x}{\text{Sr}}_{x}){\text{Fe}}_{2}{\text{As}}_{2}$ in spite of the same volume range. We show that the spin-density-wave (SDW) state of ${\text{BaFe}}_{2}{\text{As}}_{2}$ becomes suppressed in ${\text{BaFe}}_{2}{({\text{As}}_{1\ensuremath{-}x}{\text{P}}_{x})}_{2}$ by a subtle reorganization of the crystal structure, where arsenic and phosphorus are located at different coordinates ${z}_{\text{As}}$ and ${z}_{\text{P}}$. High-resolution x-ray diffraction experiments with ${\text{BaFe}}_{2}{({\text{As}}_{1\ensuremath{-}x}{\text{P}}_{x})}_{2}$ single crystals reveal almost unchanged Fe-P bonds, but a contraction of the Fe-As bonds, which remain nearly unchanged in $({\text{Ba}}_{1\ensuremath{-}x}{\text{Sr}}_{x}){\text{Fe}}_{2}{\text{As}}_{2}$. Since the Fe-As bond length is a gauge for the magnetic moment, our results show why the SDW is suppressed by P doping, but not by Sr doping. Only the Fe-P interaction increases the width of the iron $3d$ bands, which destabilizes the magnetic SDW ground state. The simultaneous contraction of the Fe-As bonds is rather a consequence of the vanishing magnetism. Ordered structure models of ${\text{BaFe}}_{2}{({\text{As}}_{1\ensuremath{-}x}{\text{P}}_{x})}_{2}$ obtained by density-functional theory calculations agree perfectly with the single-crystal x-ray structure determinations. The contraction of the Fe-As bonds saturates at doping levels above $x\ensuremath{\approx}0.3$, which corrects the unreasonable linear decrease in the so-called pnictide height.

Effect of phosphorus on cleavage fracture inκ-carbide

To understand the origin of cleavage fracture which dominates in FeMn-Al-C alloys at a high phosphorus concentration, we performed first-principles study of the phosphorus effect on ideal cleavage energy and critical stress in -carbide, Fe3AlC, a precipitate in the austenitic alloys. We find that phosphorus has higher solubility in Fe3AlC than in -Fe and sharply reduces the cleavage characteristics of -carbide. We show that strong anisotropy of the Fe-P bonds in Fe3Al,PC under tensile stress, leads to the appearance of large structural voids and may facilitate crack nucleation.

Synthesis and Characterization of Iron(II) Complexes with Tetradentate Diiminodiphosphine or Diaminodiphosphine Ligands as Precatalysts for the Hydrogenation of Acetophenone

Six complexes of the type trans-[Fe(NCMe)2(P-N-N-P)]X2 (X = BF4(-), B{Ar(f)}4(-)) (Ar(f) = 3,5-(CF3)2C6H3) containing diiminodiphosphine ligands and the complexes trans-[Fe(NCMe)2(P-NH-NH-P)][BF4]2 with a diaminodiphosphine ligand were obtained by the reaction of Fe(II) salts with achiral and chiral P-N-N-P or P-NH-NH-P ligands, respectively, in acetonitrile at ambient temperature. The P-N-N-P ligands are derived from reaction of ortho-diphenylphosphinobenzaldehyde with the diamines 1,2-ethylenediamine, 1,3-propylenediamine, (S,S)-1,2-disopropyl-1,2-diaminoethane, and (R,R)-1,2-diphenyl-1,2-diaminoethane. Some complexes could also be obtained for the first time in a one-pot template synthesis under mild reaction conditions. Single crystal X-ray diffraction studies of the complexes revealed a trans distorted octahedral structure around the iron. The iPr or Ph substituents on the diamine were found to be axial in the five-membered Fe-N-CHR-CHR-N- ring of the chiral P-N-N-P ligands. A steric clash between the imine hydrogen and the substituent probably determines this stereochemistry. The diaminodiphosphine complex has longer Fe-N and Fe-P bonds than the analogous diiminodiphosphine complex. The new iron compounds were used as precatalysts for the hydrogenation of acetophenone. The complexes without axial substituents on the diamine had moderate catalytic activity while that with axial Ph substituents had low activity but fair (61%) enantioselectivity for the asymmetric hydrogenation of acetophenone. The fact that the diaminodiphosphine complex has a slightly higher activity than the corresponding diiminodiphosphine complex suggests that hydrogenation of the imine groups in the P-N-N-P ligand may be important for catalyst activation. Evidence is provided, including the first density-functional theory calculations on iron-catalyzed outer-sphere ketone hydrogenation, that the mechanism is similar to that of ruthenium analogues.

Interplay among Tetrahedrane, Butterfly Diradical, and Planar Rhombus Structures in the Chemistry of the Binuclear Iron Carbonyl Phosphinidene Complexes Fe2(CO)6(PX)2

Density functional theory studies on a series of Fe2(CO)6(PX)2 derivatives show the tetrahedrane to be the most stable for the alkyl (X = Me, tBu), P-H (X = H), and chloro (X = Cl) derivatives. However, butterfly diradical and planar rhombus structures are found to be more stable than tetrahedranes for the amino (X = NH2, NMe2, and NiPr2) and aryloxy (R = 2,6-tBu2-4-Me-C6H2O) derivatives. For the chloro (X = Cl) and methoxy (X = OMe) derivatives energetically accessible bishomotetrahedrane Fe2(CO)6P2(mu-X)2 isomers are observed in which the X substituents on the phosphorus atoms interact with the iron atom to form two direct Fe-X bonds at the expense of two of the four Fe-P bonds. In addition, the global minimum for the hydroxy (X = OH) derivative is an unusual FeP-butterfly structure with a central Fe-P bond as well as two external Fe-P bonds, one external P-P bond, and one external Fe=Fe double bond. Comparison of calculated with experimental nu(CO) frequencies shows that low-temperature Nujol matrix photolysis of (iPr2NP)2COFe2(CO)6 leads to a planar rhombus rather than a tetrahedrane isomer of Fe2(CO)6(PNiPr2)2.

Quantum Chemistry Study on Local Structure and Properties of Amorphous Fe80P20 Alloy

According to the structure features of Fe80P20, a series of clusters Fe4P were designed and focused on studying the stability of local structure, charge distribution and chemical bond. Using the DFT method, energy and structure of Fe4P clusters were optimized and analyzed. The computational results showed that the energy of cluster 1(2) has the lowest energy, and the possibility of its existence in the Fe80P20 is high. Analyzing the transition states among the clusters, it was found that the clusters in the doublet state are more stable than those in the quartet state. The numbers of the FeP bond in the clusters play important roles in the cluster stability and electrons transfer properties. The more numbers of FeP bonds in the clusters, the higher the cluster stability, and the weaker the ability of P atom to get electron. The number of Fe atoms, which has bonding interactions with the P atom, is direct proportional to the average 3d orbit population of Fe atom. Basing on the orbital population, average magnetic moments of each Fe atom in the Fe4P clusters were calculated, and they are all smaller than that of single metal Fe atom. This suggests that all Fe4P clusters have soft magnetic property and they are expected to be perfect material for preparing soft magnetic apparatus.

Density functional theory analysis of some triple-decker sandwich complexes of iron containing cyclo-P5 and cyclo-As5 ligands

Structure and bonding in triple-decker cationic complexes [(η5-Cp)Fe(μ,η:η5-E5) Fe(η5-Cp)]+ (1: E = CH, 2: E = P, 3: E = As) and [(η5-Cp)Fe(μ,η:η5-Cp)Fe(η5-E5)]+ (E = P, As) are examined by density functional theory (DFT) calculations at the B3LYP/6-31+G* level. These species exhibit the lowest energy when all the three ligands are eclipsed. In the complexes with bifacially coordinated cyclo-E5, the perfectly eclipsed D5h sandwich structure a is found to be a potential minimum. The energy difference between the fully eclipsed and the staggered conformations b and c are within 1.0, 2.1, and 6.3 kcal/mol, respectively, for E = CH, P, and As. The isomeric species with monofacially coordinated cyclo-E5 (E =P, As), [(η5 -Cp)Fe(μ,η :η5-Cp)Fe(η5-E5)]+ are predicted to be about 30 and 60 kcal/mol higher in energy , respectively, for E = P and As. The calculations predict that the bifacially coordinated cyclo-E5 (E =P, As) undergoes significant ring expansion leading to ``loosening of bonds'' as observed experimentally. The consequent loss of aromaticity in the central cyclo-E5 indicates that significant π-electron density from the ring can be directed towards bonding with the iron centers on both sides. The diffuse nature of the π-orbitals of cyclo-P5 and cyclo-As5 can lead to better overlap with the iron d-orbitals and result in stronger bonding. This is reflected in the bond order values of 0.377 and 0.372 for the Fe-P and Fe-As bonds in 2a and 3a, respectively. The natural population analysis reveals that the Fe atom that is coordinated to a cyclo-E5 (E = P, As) possesses a negative charge of −0.23 to −0.38 units due to transfer of electron density from the inorganic ring to the metal center.

Darstellung und spektroskopische Charakterisierung von Natriumpentacyano(phosphan/phosphit)ferraten(III) / Preparation and Spectroscopic Characterization of Sodium Pentacyano(phosphane/phosphite)ferrates(III)

Abstract Sodium pentacyanoferrates(III) of the type Na2[Fe(CN)5L] (L = phosphane or phosphite) have been prepared from sodium pentacyanoferrates(II), Na3[Fe(CN)5L], by bromine oxidation and characterized by Mössbauer, IR, and electronic spectroscopy. Isomer shifts and quadrupole splittings lie within the range commonly found in low-spin iron(III) complexes. A linear correlation was found between isomer shifts and CN stretching and Fe-CN bending frequencies, respectively. The spectroscopic parameters show that the dπ-dπ back bonding of the Fe-P bonds is synergetically strengthened with increasing σ donor capability of the phosphorus ligands.

Atomistic studies of grain boundary segregation in Fe-P and Fe-B alloys—II. Electronic structure and intergranular embrittlement

The local density of states (LDOS) of electrons at grain boundaries of iron with or without segregation (phosphorus or boron) was calculated. The grain boundary structures constructed by using empirical atomic pair potentials were used as the model systems. The hopping integrals were calculated by using the linear-muffin-tin orbitals and atomic sphere approximation. The atomic level of the individual atomic site near the grain boundary is determined so as to maintain the charge neutrality at each atomic site. Following results were obtained: 1. (1) In the grain boundaries of iron without impurities, the non-bonding orbitals are formed at the Fe-3d bands at the grain boundary, while LDOS's of the neighboring atoms have the bonding orbitals perpendicular to the boundary. 2. (2) When boron atoms segregate at the boundary, the non-bonding states of the iron atom disappear by forming the strong bonding orbital with the B-2p orbital, and the grain boundary is strengthened. 3. (3) In case of the phosphorus segregation, the non-bonding states are formed at LDOS's of Fe-3d electrons surrounding the Fe 9P cluster, and the Fe-Fe bonds are weakened, although the Fe-P bonds in the Fe 9P cluster are strengthened. 4. (4) The binding character is determined not only directly by the nature of impurity, but also indirectly by the structural change induced by the impurity segregation. Especially in the case of phosphorus segregation, the structural change reduces the bonding character of the host atoms.