Crystal structures and vibrational spectra ofMSnF6·6H2O(M=Fe,Co, Ni)

Summary Single crystal X-ray structural data (atT=300 K) are reported for CoSnF₆·6H₂O (rhombohedral; R{ie61-1}-C _3i ² ;a=9.735(7) Å,c=10.095(7) Å, =120°;Z=3;R=0.047) and for NiSnF₆· 6H₂O (rhombohedral; R{ie61-2}-C _3i ² ;a=9.697(1)Å,c=10.021(1)Å, =120°;Z=3;R=0.038). The two compounds are isostructural to FeSnF₆·6H₂O. IR and Raman spectroscopic data (atT=300 and 75 K) are reported for hydrated and for partially deuterated samples ofMSnF₆·6H₂O (M=Fe, Co, Ni). Two rather similar (OD) stretching frequencies and one (HDO) bending frequency of isotopically dilute HDO molecules are observed for either of the three compounds, which is consistent with one crystallographically distinct water molecule forming two different, but rather similar O ... F hydrogen bonds.

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Kristallstrukturen und Schwingungsspektren vonMSnF₆·6H₂O (M=Fe, Co, Ni)

Zusammenfassung Die Kristallstrukturen von CoSnF₆·6H₂O (rhomboedrisch; R{ie61-3}-C _3i ² ;a=9.735(7) Å,c=10.095(7) Å, =120°;Z=3;R=0.047) und von NiSnF₆·6H₂O (rhomboedrisch; R{ie61-4}-C _3i ² ;a=9.697(1)Å,c=10.021(1)Å, =120°;Z=3;R=0.038) wurden mittels Röntgen-Einkristalldaten (beiT=300 K) bestimmt. Die beiden Verbindungen sind isostrukturell zu FeSnF₆·6H₂O. IR- und Raman-Spektren vonMSnF₆·6H₂O (M=Fe, Co, Ni) wurden von Proben mit unterschiedlichem Deuterierungsgrad gemessen (beiT=300 und 75 K). Bei allen drei Verbindungen findet man für isotopenverdünnte HDO Moleküle zwei nur geringfügig unterschiedliche (OD)-Valenzfrequenzen und eine (HDO)-Deformationsfrequenz, was mit der Existenz von nur einer Art von Wassermolekülen mit zwei verschiedenen, aber doch sehr ähnlichen O ... F Wasserstoffbrückenbindungen übereinstimmt.

     

Synthesis, Crystal Structure, and Properties of Inorganic-organic Hybrid M(Ⅱ)-Nb(Ⅴ)(M = Co, Cu)Oxyfluorides

T Two isostructural inorganic-organic hybrid M(Ⅱ)-Nb(Ⅴ)oxyfluorides, namely,M(H<,2>O)<,2>(pyz)NbOF<,5>(M = Co 1, Cu 2; pyz = pyrazine)have been hydrothermally synthesized and structurally characterized. Both compounds possess two-dimensional layer structure constructed by neutral M(H<,2>0)<,2>NbOF<,5> chains inter-connected via bridging pyrazine ligands. The structure is further extended into three-dimensional supramolecular architecture through inter-layer H-bonding interactions between the coordinated water molecules and fluorine ions. The luminescent properties and thermal stability of both compounds have been investigated.     

Single Crystal Studies of Ternary Transition-Metal Molybdenum Selenides MMo6Se8 (M = Ti, Fe, Mn, Cr and Co)

Magnetic properties have been measured in single crystals of selenium-based Chevrel-type M _xMo₆Se₈, with M = Ti, Fe, Mn, Cr and Co, in which x(M) is equal to unity, except for Ti (x ~ 0.9) and Co (x ~ 0.5). Presence of impurities, such as the binary Mo₃Se₄ sub-product, is absolutely excluded and reported results are representative of the intrinsic properties of the reported compounds. For polycrystalline ScMo₆Se₈ and single crystals of Ti_0.88Mo₆Se₈, the Pauli-like temperature-independent magnetic susceptibility allows having a good estimation of the non-magnetic contribution of the Mo₆Se₈ sublattice. Crystal field effects were seen for polycrystalline VMo₆Se₈. Spectacular results were obtained for FeMo₆Se₈ (canted antiferromagnetic compound with high magnetic anisotropy), CrMo₆Se₈ (antiferromagnetism, T_N = 12 K), MnMo₆Se₈ (metamagnetic compound) while the properties of Co_0.54Mo₆Se₈ can be interpreted by magnetic exchange interactions J_AF ~ 100 K. These results are discussed in connection with structural properties and transport measurements obtained in single crystal specimens.     

Electrophilic Substitution Mn(II) → M(II) (M = Co,Ni, Cu,Zn, Cd) in Gelatin-Immobilized Mn2[Fe(CN)6]

Reactions of electrophilic substitution Mn(II) M(II) (M = Co, Ni, Cu, Zn, Cd) are studied in gelatin-immobilized Mn(II) hexacyanoferrate(II) systems brought in contact with aqueous solutions of metal chlorides MCl₂. As the result of this contact, Mn(II) is replaced by Co(II), Ni(II), Cu(II), Zn(II), or Cd(II) to give heteronuclear metal hexacyanoferrates(II) (MHCF) of Mn(II) and two-charged ions. Neither of the systems under study showed a complete substitution of Mn(II) or the formation of the respective mononuclear hexacyanoferrate(II) M₂[Fe(CN)₆]. When any of the above gelatin-immobilized MHCF was brought in contact with an aqueous solution of MnCl₂, no electrophilic substitution M(II) Mn(II) was observed even for a long contact time.     

Electrophilic Substitution Co(II)→M(II) (M = Mn,Ni, Cu,Zn, Cd) in Co2[Fe(CN)6] Gelatin-Immobilized Matrices

Electrophilic substitutions Co(II) M(II) (M = Mn, Ni, Cu, Zn, Cd) in cobalt(II) hexacyanoferrate(II) gelatin-immobilized matrices in contact with aqueous solutions of corresponding chlorides MCl₂ were studied. As a result of this contact, Co(II) was shown to be replaced to some extent by Ni(II), Cu(II), Zn(II), or Cd(II) and to give heteronuclear cobalt(II) hexacyanoferrates(II) and two-charge ions. A complete substitution of Co(II) or the formation the respective mononuclear hexacyanoferrate(II) M₂[Fe(CN)₂] was observed in neither of the studied systems Co(II) M(II). No Co(II) Mn(II) substitution was observed, even though the immobilized matrix was in contact with a solution for a long time.     

Phase relationships of the quaternary systems MCr2Se4MGa2Se4 (M = Mn,Fe, Co,Ni): New layered ZnIn2S4-III type selenides

The phase relationships of the quaternary systems MCr₂Se₄MGa₂Se₄ (M = Mn, Fe, Co, Ni) and MV₂S₄MGa₂S₄ (M = Fe, Ni) and the ternary system NiSGa₂S₃ were studied by X-ray phase analyses with the aim to prepare new layered structure and spinel-type chalcides. The hitherto unknown selenides MnCr_0.5Ga_1.5Se₄, FeCr_0.5Ga_1.5Se₄, CoCr_0.5Ga_1.5Se₄, and (Ni, Cr, Ga, □)₃Se₄ (all ZnIn₂S₄-III type) were obtained and characterized by X-ray and FIR studies. No quaternary chalcides are formed in the systems MV₂S₄MGa₂S₄; ternary NiGa₂Se₄ and CoGa₂Se₄ were likewise not obtained. Whereas the phase widths of the end-member phases are small (with the exception of α′-Ga₂S₃ at 1000°C) because of the strong tetrahedral and octahedral site preferences of gallium and both chromium and vanadium, respectively, the quaternary selenides form solid solutions of the type MCr_2−2xGa_2xSe₄ with x = 0.65-0.80 for M = Mn and Fe.     

氧心羧桥异三核过渡金属簇合物[Fe2MO(CH3COO)6Py3].Py(1,M=Mn;2,M=Co;3,M=Ni)和[Fe2MO(CCl3COO)6(THF)3](4,M=Mn;5,M=Co;6,M=Ni)电子光谱的研究

The UV/VIS spectra for pyridine solution of complexes [Fe_2MO(CH_3COO)_6Py_2]·Py and THF solution of complexes Fe_2MO(CCl_3COO)_6(THF)_3 were studied. The d-d transitions were assigned and the ligand field parameters(B,D_q,β) were calculated for the related metal ions according to ligand field theory (Tanabe-Sugano diagram) in terms of O_h symmetry and reasonably good fits were obtained for the calculated and observed frequencies. The calculated results show that (1) the larger the ionic potential for M~(2+) ion, the larger the values of B, D_q for Fe~(3+) ion (2) the ligand field parameters of metal ions vary in parallel with the electronagativity of R in RCOO~-.     

Syntheses,Crystal Structures and Different Magnetic Behaviors of Three Cyanide-bridged Fe~(Ⅱ)-M~(Ⅱ)(M = Fe,Co and Mn) Complexes

Three dinuclear cyanide-bridged complexes[Fe~(Ⅱ)(PY_5OMe_2)CNM~(Ⅱ)(PY_5OMe_2)](OTf)_3 (M=Fe1,M=Co 2,M=Mn 3)(PY_5OMe_2=2,6-bis-((2-pyridyl)methoxymethane)pyridine OTf=CF_3SO_3~-) have been synthesized and characterized.Single-crystal diffraction analyses show these three dinuclear compounds are very similar in structure.The measuredν(CN) results for compounds 1～3 suggest that Mn~(2+)is electron-poorer than Fe~(2+)and Co~(2+).Meanwhile,the temperature dependence of magnetic susceptibilities of complexes 1～3 reveals that in these three complexes,all the cyanide-carbon coordinated Fe(Ⅱ) is low-spin,and Co(Ⅱ) for 2 and Mn(Ⅱ) for 3are both in a high-spin state through 2～400 K but the cyanide-nitrogen coordinated Fe(Ⅱ) for complex 1 exhibits spin crossover (SCO) behavior over 300 K and a hysteresis of 36 K in both cooling and heating modes.     

Synthesis and Structures of New Borophosphates (B_(1-X)M_X)PO_4 (M=Mn,Fe,Co,Ni,Cu) with Orthorhombic Low-Cristobalite Type

TwomodificationsofBPO4-theletragonalhigh-cristobalite'andthehexagonalhighpressurephase=,havebeenf0und.Thehigh-cristobalitephasehasIongbeenusedasmulti-functionaIcataIyst'.Wereportherethesynthesis,structureretinementsofnewborophosphateswithIow-cristobaIitestructurestabiIizedbytransitionmetalsMn,Fe,Co,NiandCu.andtheirmagneticproperties.AllthestartingreagentsfH3BO3,NH4H2PO4,MnO2,Fe2O3,Co(CH3COO)2.4H2O,Ni(CH3C00)2.4H20,Cu0wereinARpuritiesandweIlground,pre-reactedat7OOaCfor4handfin…     

Ion-Exchange Processes M(II) → Fe(III) and Fe(III) → M(II) in Metal Hexacyanoferrate(II) Gelatin-Immobilized Matrices (M = Mn,Co, Ni,Cu, Zn,Cd)

Ion-exchange reactions M²⁺ Fe³⁺ and Fe³⁺ M²⁺ (M = Mn, Co, Ni, Cu, Zn, Cd) were studied in metal(II) hexacyanoferrate(II) gelatin-immobilized matrices M₂[Fe(CN)₆] in contact with aqueous FeCl₃ solutions and Fe₄[Fe(CN)₆]₃ in contact with aqueous MCl₂ solutions. It was shown that in both cases, M²⁺ was replaced by Fe³⁺ and Fe³⁺ was replaced by M²⁺ to some extent, but no complete replacement was observed in the M₂[Fe(CN)₆]–FeCl₃ or Fe₄[Fe(CN)₆]₃–MCl₂ systems under study. No electrophilic substitution Fe³⁺ Mn²⁺ was found to occur in any noticeable degree during the contact of Fe₄[Fe(CN)₆]₃ with aqueous MnCl₂ solutions even when this contact occurred for 1 h and longer.     

Hexanuclear Fe(III)2Co(III)2M(II)2 (M = Cu, Ni, Mn) clusters based on Kläui's tripodal ligand and tricyanometalates: syntheses, structures and magnetic properties

With the use of Kl?ui's tripodal ligand, [(Cp)Co(P(O)(OEt)(2))(3)](-) (L(CoEt), Cp = cyclopentadiene) as the auxiliary ligand to react with different metal salts and tricyanometalate building blocks, five neutral trimetallic hexanuclear complexes: [(Tp)(2)Fe(2)(CN)(6)Cu(2)(L(CoEt))(2)]·6H(2)O (1, Tp = hydridotris(pyrazolyl)borate), [(Tp*)(2)Fe(2)(CN)(6)Cu(2)(L(CoEt))(2)]·2H(2)O (2, Tp* = hydridotris(3,5-dimethyl-pyrazolyl)borate), [(pzTp)(2)Fe(2)(CN)(6)Cu(2)(L(CoEt))(2)]·H(2)O·3MeOH (3, pzTp = tetra(pyrazolyl)borate), [(Tp)(2)Fe(2)(CN)(6)Ni(2)(L(CoEt))(2)(MeCN)(2)]·2MeCN·2H(2)O (4) and [(Tp)(2)Fe(2)(CN)(6)Mn(2)(L(CoEt))(2)(MeCN)(2)]·2MeCN (5), have been obtained and structurally characterized. Magnetic measurements confirm that there are ferromagnetic couplings between the cyano-bridged Fe and Cu/or Ni ions and antiferromagnetic interaction between the cyano-bridged Fe and Mn ions. Slow relaxation of the magnetization is observed in complexes 1 and 4, while complex 3 exhibits metamagnetic behavior with a critical field of 17.5 kOe.     

Intermediates-induced CO2 Reduction Reaction Activity at Single-Atom M−N2 (M=Fe,Co, Ni) Sites

Single-atom M−N₂ (M=Fe, Co, Ni) catalysts exhibit high activity for CO₂ reduction reaction (CO₂RR). However, the CO₂RR mechanism and the origin of activity at the single-atom sites remain unclear, which hinders the development of single-atom M−N₂ catalysts. Here, using density functional theory calculations, we reveal intermediates-induced CO₂RR activity at the single-atom M−N₂ sites. At the M−N₂ sites, the asymmetric *O*CO configuration tends to split into *CO and *OH intermediates. Intermediates become part of the active moiety to form M−(CO)N₂ or M-(OH)N₂ sites, which optimizes the adsorption of intermediates on the M sites. The maximum free energy differences along the optimal CO₂RR pathway are 0.30, 0.54, and 0.28 eV for Fe−(OH)N₂, Co−(CO)N₂, and Ni−(OH)N₂ sites respectively, which is lower than those of Fe−N₂ (1.03 eV), Co−N₂ (1.24 eV) and Ni−N₂ (0.73 eV) sites. The intermediate modification can shift the d-band center of the spin-up (minority) state downward by regulating the charge distribution at the M sites, leading to less charge being accepted by the intermediates from the M sites. This work provides new insights into the understanding of the activity of single-atom M−N₂ sites.     

“From Heteronuclear Complex to Composite Oxide” Approach in the Synthesis of Nanosized Ferrites MIIFeIII 2O4 (M = Mn,Co, Ni) with Spinel Structure and Their Catalytic Properties

A study was carried out on the preparation of ferrites M^IIFe₂O₄ (M^II = Mn, Co, Ni) by the thermal decomposition of the corresponding ₃-oxoacetates [Fe₂M^IIO(CH₃COO)₆(H₂O)₃]·2H₂O. Nanocrystallites of M^IIFe₂O₄ were formed under mild conditions at 300-400 °C in this reaction. An increase in the temperature leads to an increase in particle size. Nickel ferrite showed high catalytic activity in the reduction of nitrogen oxides (NO _x ) by hydrocarbons.     

Syntheses and Crystal Structures of Four New Complexes [Mn(4,4′-bip)_2(OH_2)_4](DBA)·4H_2O and [M(OH_2)(HDPA)_2]·3H_2O (M = Mn,Co,Ni)

1 INTRODUCTION During the past years, dicarboxylic acids have been widely used as one polydentate ligand invo- lved in various metal chelation reactions to form transition or rare earth metal complexes with inter- esting properties in material science[1] and biological systems[2]. For example, Kim Y and his coworkers focused on the synthesis of copper(II) complexes containing malonate and pyrazine ligands to study their magnetic property and electronic conducti- vity[3]. The importance o…     

K_2NiF_4型Dy_(0.5)Sr_(1.5)MO_4(M=Mn,Fe,Co,Ni)稀土复合氧化物的合成和催化性能考察

用重稀土镝的氧化物与锶、锰、铁、钴、镍的硝酸盐为原料,制备了A_2BO_4型Dy_(0.5)Sr_(1.5)MO_4(M=Mn,Fe,Co,Ni)稀土复合氧化物,用XRD技术考察了物相,合成了K_2NiF_4型四方结构的Dy_(0.5)Sr_(1.5)MO_4,并研究了其催化性能。对结构容纳因子的适用性作了讨论。     

The reaction mechanism of a M (M = Mn,Fe, Co and Ni) atom inserted into a Fe8O12 cage

Research on Chemical Intermediates - The reaction process of a M (M?=?Mn, Fe, Co and Ni) atom associated and then interpolated into a Fe8O12 cage is calculated by using a PBE...     

Magnetic properties of isostructural M(H2O)4[Au(CN)4]2-based coordination polymers (M = Mn, Co, Ni, Cu, Zn) by SQUID and μSR studies

A series of isomorphous M(H(2)O)(4)[Au(CN)(4)](2)·4H(2)O (M = Mn, Co, Ni, Zn; Cu is similar) coordination polymers was synthesized from the reaction of M(II) with KAu(CN)(4); they consist of octahedrally coordinated metal centres with four equatorial water molecules and trans-axial N-cyano ligands from [Au(CN)(4)](-) moieties, generating a linear 1-D chain of M(H(2)O)(4)[Au(CN)(4)]-units. An additional interstitial [Au(CN)(4)](-) unit forms AuN and hydrogen bonds with adjacent chains. The Cu(II) system readily loses water to yield Cu[Au(CN)(4)](2)(H(2)O)(4), which was not structurally characterized. The magnetic properties of these polymers were investigated by a combination of SQUID magnetometry and zero-field muon spin relaxation (ZF-μSR). Only weak antiferromagnetic interactions along the chains are mediated by the [Au(CN)(4)]-units, but the ZF-μSR data indicates that interchain interactions yield a phase transition to a magnetically ordered state for Cu[Au(CN)(4)](2)(H(2)O)(4) below 0.6 K, while for M(H(2)O)(4)[Au(CN)(4)](2)·4H(2)O (M = Co), depopulation of zero-field split Kramer's doublets to an effective "S = 1/2" ground state yields a transition to a spin-frozen magnetic state below 0.26 K. On the other hand, only a simple slowing-down of spins above 0.02 K is observed for the more weakly zero-field split M(H(2)O)(4)[Au(CN)(4)](2)·4H(2)O (M = Mn, Ni) complexes.     

Catalytic Performance in CO Hydrogenation Over SiO_2-Supported Ru-M (M=Co, Fe,Mo,Ni,Rh,Mn and Cr) Bimetallic Cluster-derived Catalysts

The bimetallic Ru-M (M=Co,Fe,Ni,Mo, Rh,Cr, Mn) catalysts were prepared from SiO_2-supported bimetallic carbonyl clusters, and it was found that the Ru-Co, Ru-Fe and Ru-Mo bimetallic carbonyl cluster-derived catalysts showed higher activity and selectivity for oxygenates such as C_1-C_5 alcohols in CO hydrogenation,in contrast to catalysts prepared from SiO_2-supported homometallic Ru and Co carbonyl clusters. In situ FT-IR studies revealed that the bands at 1584 and 1555 cm~(-1) species were intermediates to produce methanol and higher oxygenates,and at higher temperatures the 1584 cm~(-1) species could react with alkyl to form 1555 cm~(-1) species. By the surface chemical reaction and the IR study of isotopic molecules,it was suggested that 1584 and 1555 cm~(-1) were assigned to surface formyl and acetyl species.     

Three 3D M~Ⅱ (M = Co,Ni, Zn) Supramolecular Polymers Constructed from O-vanillic Acid: Synthesis,Crystal Structure and TGA

The title compounds, [Co(H2O)6](OVA)2·2H2O 1, [Ni(H2O)6](OVA)2·2H2O 2 and [Zn(OVA)2·2H2O] 3 (HOVA = o-vanillic acid = 2-hydroxy-3-methoxybenzoate), were synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR and TGA. Compounds 1 and 2 are both of triclinic with space group P1. The metal atom coordinated by six water molecules displays a slightly distorted octahedral configuration. Interestingly, the carboxyl group from HOVA ligand does not coordinate to the metal atom. Correspondingly, compound 3 belongs to the monoclinic system, space group C2/c. Each zinc(Ⅱ) atom exhibits a distorted four-coordinated tetrahedral geometry. Two monodentate carboxyl groups link one zinc(Ⅱ) atom to form a mononuclear molecule. The structure feature is different from that of compounds 1 and 2, which could be attributed to the different coordinated numbers and radii of Co(Ⅱ), Ni(Ⅱ) and Zn(Ⅱ) atoms.