Cyanide-bridged W(V)-Mn(II) bimetallic double-zigzag chains with a metamagnetic nature

A cyanide-bridged W-Mn bimetallic compound [W(CN)(6)(bpy)](2)[Mn(H(2)O)(2)].4H(2)O (1) (bpy = 2,2'-bipyridine) with a one-dimensional, crossed double-zigzag chain structure was prepared by self-assembling [W(CN)(6)(bpy)](-) and Mn(2+) ions in a 2:1 reaction ratio. The magnetic properties of 1 exhibit a field-induced metamagnetic behavior.     

Cyanide-bridged W(V)-Co(II) double-zigzag chain based on an octacoordinated W precursor: metamagnetism and spin canting

A cyanide-bridged W-Co bimetallic complex (1) with a double-zigzag chain structure was characterized in terms of structure and magnetism. Compound 1 exhibits metamagnetism and spin canting induced by the presence of anisotropic CoII ions and noncovalent interactions.     

Extremely long axial Cu-N bonds in chiral one-dimensional zigzag cyanide-bridged Cu(II)(-)Ni(II) and Cu(II)(-)Pt(II) bimetallic assemblies

Preparations, crystal structures, and spectral and magnetic properties of two new chiral one-dimensional cyano-bridged coordination polymers, [Cu(II)L2]M(II)(CN)].2H2O (M(II) = Ni(II) (1) and Pt(II) (2), L = trans-cyclohexane-(1R,2R)-diamine) have been presented. Complex 1 crystallizes in the monoclinic P2(1) space group with a = 9.864(4) A, b = 15.393(8) A, c = 7.995(4) A, beta = 110.32(3) degrees , V = 1138.4(10) A3, and Z = 2, while 2 crystallizes in the monoclinic P2(1) space group with a = 9.899(3) A, b = 15.541(4) A, c = 8.102(2) A, beta = 111.02(2) degrees , V = 1163.6(5) A3, and Z = 2. The unique zigzag cyano-bridged chains along the crystallographic b axis consist of alternate chiral [CuL(2)]2+ cations and square-planar [M(CN)4]2- anions. One side of the axial Cu-N(triple bond C) bond distances are 2.324(6) and 2.34(1) A with Cu-N[triple bond]C angles of 137.8(6) degrees and 138.2(9) degrees for 1 and 2, respectively. On the other hand, the opposite side of the axial Cu-N(triple bond C) bond distances are 3.120(8) and 3.09(1) A with significantly large bent Cu-N[triple bond]C angles of 97.9(5) degrees and 96.8(7) degrees for 1 and 2, respectively. The novel axial bonding features of extremely long semi-coordination Cu-N bonds are attributed to coexistence of pseudo-Jahn-Teller elongation and electrostatic interaction in the unique zigzag cyano-bridged chains. The characteristic bonding features with overlap between small 3d (Ni(II)) or large 5d (Pt(II)) and 3d (Cu(II)) orbitals results in larger shifts in XPS peaks of not only Cu2p(1/2) and Cu2p(3/2) but also Ni2p(1/2) and Ni2p(3/2) for 1 than those of 2, which is also consistent with weak antiferromagnetic interactions with Weiss constants of -5.31 and -5.94 K for 1 and 2, respectively. The d-d, pi-pi*, and CT bands in the electronic, CD, and MCD spectra for 1 and 2 in the solid state at room temperature are discussed from the viewpoint of magneto-optical properties.     

Two bimetallic W(IV)-Mn(II) complexes based on octacyanometallates: structures and magnetic properties

Two cyano-bridged heterobimetallic coordination polymers, [{Mn(dpa)₂}₂W(CN)₈·CH₃CN·₄H₂O] _n (1) (dpa = 2,2′-dipyridylamine) and [Mn₂(H₂O)₄{W(CN)₈}·3H₂O] _n (2), have been synthesized and characterized structurally and magnetically. X-ray analysis shows that complex 1 is a one-dimensional (1-D) polymer of W₂(CN)₄Mn₂ square units in which adjacent square fragments are interlinked by sharing [W(CN)₈]^4? moieties to form an infinite chain. Complex 2 is a three-dimensional (3-D) polymer, which shows an unforeseen structure, exhibiting a 3-D open network with a 1-D channel (ca.13.21 Å × 11.82 Å). Fitting of the magnetic properties indicates that both polymers exhibit weakly antiferromagnetic interactions between the adjacent Mn ions.     

Two octacyanomolybdate(IV)-M(II) (M = Mn,Co) bimetallic assemblies: Crystal structures and magnetic properties

Two cyano-bridged bimetallic complexes {[M₂(H₂O)₄Mo(CN)₈] · 4H₂O} _n [M = Mn (I) and Co (II)] have been synthesized and structurally characterized. The single-crystal X-ray analyses reveal that these two compounds have three-dimensional structures, and cell parameters are similar in a tetragonal system with space group I $ \bar 4 $ \bar 4 . In the both complexes, each [Mo(CN)₈]⁴⁻ building block is linked with M²⁺ [M = Mn and Co] ions through its eight CN ligands. Each M²⁺ center is connected to four Mo units forming a three-dimensional framework. In addition, magnetic studies of these complexes have been presented.     

Micro-determination of As(V), V(V), Mo(VI), W(VI) in the presence of Cu(II), Ni(II) and Zn(II)

A rapid procedure is described for the separation and determination of 0.025 mg to 1.0 mg quantities of As(V), V(V), Mo(VI) and W(VI) from small quantities of Cu(II), Ni(II), and Zn(II) using silica gel as the selective sorbent for the cations. The individual anionic components, which remain in the supernatant solution after separation from the cations, are determined by colorimetric methods. The complete recovery of As(V) in supernatant solution has also been tested radiometrically using⁷⁶As as the radioactive indicator. The sorbed cations after extraction with dilute hydrochloric acid are determined by EDTA titrations.     

Oxalato complexes of Pd(II) with Co(II) and Ni(II) as single-source precursors for bimetallic nanoalloys

Journal of Thermal Analysis and Calorimetry - The explanation of abnormal enhancement of transported energy in colloidal nanoparticles in a liquid has sparked much interest in recent years. The...     

Isomorphous Co(II) and Ni(II) antiferromagnets based on mixed azide- and carboxylate-bridged chains: metamagnetism and single-chain dynamics

Two isomorphous Co(II) and Ni(II) coordination polymers with azide and the 4-(4-pyridyl)benzoic acid N-oxide ligand (4,4-Hopybz) were synthesized, and structurally and magnetically characterized. They are formulated as [M(4,4-opybz)(N(3))(H(2)O)](n) (M = Co, 1 and Ni, 2). The compounds consist of 2D coordination networks, in which 1D coordination chains with (μ-N(3))(μ-COO) bridges are interlinked by the 4,4-opybz spacers, and the structure also features intra- and interchain O-HO hydrogen-bonding bridges between metal ions. Both compounds exhibit ferromagnetic interactions through the intrachain (μ-N(3))(μ-COO)(O-HO) bridges and antiferromagnetic interactions through the interchain O-HO bridges. The ferromagnetic chains are antiferromagnetically ordered, and the antiferromagnetic phases exhibit field-induced metamagnetic transition. It is found that 1 displays slow relaxation of magnetization, typical of single-chain magnets, while 2 does not. The difference emphasizes the great importance of large magnetic anisotropy for single-chain-magnet dynamics.     

One-dimensional octacyanomolybdate-based Cu(II)--Mo(V) bimetallic assembly with a novel rope-ladder chain structure

A new type of one-dimensional cyanide-bridged Cu(II)--Mo(V) bimetallic assembly, [Cu(cyclam)](3)[Mo(CN)(8)](2)x5H(2)O (cyclam = 1,4,8,11-tetraazacyclotetradecane), was prepared by self-assembling Mo(CN)(8)(3)(-) and Cu(cyclam)(2+) ions in a 2:3 stoichiometric ratio. The overall molecular view is delineated as a novel rope-ladder chain structure. It displays a dominant ferromagnetic behavior within a pentanuclear Cu(3)Mo(2) unit (J(p) = 3.88 cm(-)(1)). Interunit ferromagnetic interactions (J(c) = -0.03 cm(-)(1)) through a longer magnetic pathway of Cu--Mo and weak antiferromagnetic couplings (zJ' = -0.46 cm(-)(1)) resulting from interchain interactions are obtained.     

Synthesis,crystal structure,and magnetic properties of an octacyanometallate-based Ni/Mo bimetallic complex with the diamond topological network

Reaction of [NiL]²⁺ (L = 3,10-diethyl-1,3,5,8,10,12-hexaazacyclotetradecane) with [Mo(CN)₈]^4? leads to a new Ni₂Mo complex [Ni(L)]₂[Mo(CN)₈] · 8H₂O (1), which displays a 3-D diamond topological network. Magnetic study indicates a combination of zero-field splitting of Ni²⁺ in an axially distorted octahedral coordination and weak antiferromagnetic interactions between Ni²⁺ centers through diamagnetic [Mo(CN)₈]^4? bridges.     

Lanthanide-ion-tuned magnetic properties in a series of three-dimensional cyano-bridged Ln(III)W(V) assemblies

The reaction of [W(CN)(8)](3-) with Ln(3+) and pyrazine in acetonitrile yielded a series of isostructural compounds formulated as Ln(H(2)O)(4)(pyrazine)(0.5)W(CN)(8) (Ln = La(1), Ce(2), Pr(3), Nd(4), Sm(5), Eu(6), Gd(7)). The Ln(iii) and W(v) centers in the structure are linked through cyanide groups to form two-dimensional (2D) layers, which are further pillared by pyrazine, generating 3D frameworks. The magnetic behavior for compounds 1-7 were driven by the lanthanide ions involved. The Ln(iii) and W(v) ions in compounds 2 and 5 are ferromagnetically coupled with magnetic ordering occurring at 2.8 K, comparable with magnetic ordering with the critical temperature of 1.9 K for compound 4. In addition, the antiferromagnetic interactions were observed in compounds 3 and 7, while no significant magnetic couplings were found in compounds 1 and 6.     

Complexes of Co(II), Ni(II), Cu(II), and Pd(II) with Sulfametrole-Cyclodiphosph(V)azane Derivatives

Novel [1,3-di-[N ₁ -4-methoxy-1,2,5-thiadiazole-3-yl-sulfanilamide(sulfametrole)]-2″4-bis-[1,3-dithiole-2-thione-4,5-dithiolate]-2′,4′-dichl-orocyclodiphosph(V)azane] (III) , was prepared and their coordinating behavior towards the metal ions Co(II), Ni(II), Cu(II), and Pd(II) was studied. The structures of the isolated products are proposed based on elemental analyses, IR, UV, ¹ H, and ³¹ P NMR, ESR, magnetic susceptibility, molar ratio, conductometric titration and electrical conductivity measurements. The prepared complexes showed high to moderate bactericidal activity compared with the ligand.     

Physicochemical Investigation on the Complexes of Co(II), Ni(II) and Cu(II) with Aminocyclodiphosph(V)azane Derivative

Co(II), Ni(II), and Cu(II) form 2:1 complexes with aminocyclodiphosph(V)azane derivative. The complexes have been investigated in solution by the spectrophometric molar ratio and conductometeric methods. The ligand and its complexes have been isolated in solid state and characterized on the basis of microanalytical, infrared, electronic, magnetic moment, 1 H NMR and mass spectral data. The cobalt and nickel complexes were assigned to be in tetrahedral structure while the copper complex is assigned to be in square planar.     

High-spin molecules: synthesis,X-ray characterization,and magnetic behavior of two new cyano-bridged Ni(II)(9)Mo(V)(6) and Ni(II)(9)W(V)(6) clusters with a S = 12 ground state

The preparations, X-ray structures, and magnetic characterizations are presented for two new pentadecanuclear cluster compounds: [Ni(II)(Ni(II)(MeOH)(3))(8)(mu-CN)(30)(M(V)(CN)(3))(6)].xMeOH.yH(2)O (M(V) = Mo(V) (1) with x = 17, y = 1; M(V) = W(V) (2) with x = 15, y = 0). Both compounds crystallize in the monoclinic space group C2/c, with cell dimensions of a = 28.4957(18) A, b = 19.2583(10) A, c = 32.4279(17) A, beta = 113.155(6) degrees, and Z = 4 for 1 and a = 28.5278(16) A, b = 19.2008(18) A, c = 32.4072(17) A, beta = 113.727(6) degrees, and Z = 4 for 2. The structures of 1 and 2 consist of neutral cluster complexes comprising 15 metal ions, 9 Ni(II) and 6 M(V), all linked by mu-cyano ligands. Magnetic susceptibilities and magnetization measurements of compounds 1 and 2 in the crystalline and dissolved state indicate that these clusters have a S = 12 ground state, originating from intracluster ferromagnetic exchange interactions between the mu-cyano-bridged metal ions of the type Ni(II)-NC-M(V). Indeed, these data show clearly that the cluster molecules stay intact in solution. Ac magnetic susceptibility measurements reveal that the cluster compounds exhibit magnetic susceptibility relaxation phenomena at low temperatures since, with nonzero dc fields, chi"(M) has a nonzero value that is frequency dependent. However, there appears no out-of-phase (chi"(M)) signal in zero dc field down to 1.8 K, which excludes the expected signature for a single molecule magnet. This finding is confirmed with the small uniaxial magnetic anisotropy value for D of 0.015 cm(-1), deduced from the high-field, high-frequency EPR measurement, which distinctly reveals a positive sign in D. Obviously, the overall magnetic anisotropy of the compounds is too low, and this may be a consequence of a small single ion magnetic anisotropy combined with the highly symmetric arrangement of the metal ions in the cluster molecule.     

A dinuclear Ni(II) complex with two types of intramolecular magnetic couplings: Ni(II)-Ni(II) and Ni(II)-TTF*+

A dinuclear Ni(II) complex involving tetrathiafulvalene (TTF) radicals as ligands has been prepared and characterized, [Ni2(mu-Cl)2(L*+)2(I3)4(I2)3.(H2O)2.(C4H8O)3 (1), L = 4,5-bis(2-pyridylmethylsulfanyl)-4',5'-ethylenedithiotetrathiafulvalene. There are two types of intramolecular magnetic exchange interactions, namely one ferromagnetic Ni(II)-Ni(II) and one antiferromagnetic Ni(II)-TTF*+. This study is new in the respect of revealing a magnetic exchange interaction between a TTF*+ radical and a paramagnetic transition metal ion. This is due to the fact of a direct binding of the transition metal ion to the skeleton of the TTF*+ radical.     

Crystal structure and magnetic properties of an octacyanometalate-based three-dimensional tungstate(V)-manganese(II) bimetallic assembly

A single crystal of the title compound [MnII6(H2O)9[W(V)(CN)8]4 x 13H2O]n was synthesized in a hot aqueous solution containing octacyanotungstate, Na3[W(CN)8] x 3H2O, and Mn(ClO4)2 x 6H2O. The compound crystallized in the monoclinic system, space group P2(1)/c with cell constants a = 15.438(2) A, b = 14.691(2) A, c = 33.046(2) A, beta = 94.832(9) degrees, and Z = 4. The crystal consists of a W(V)-CN-MnII linked three-dimensional network [[MnII(H2O)]3[MnII(H2O)2]3[W(V)(CN)8]4]n and H2O molecules as crystal solvates. There are two kinds of W sites: one is close to a dodecahedron geometry with six bridging and two terminal CN ligands; the other is close to a bicapped trigonal prism with seven bridging and one terminal CN ligands. The field-cooled magnetization measurement showed that the compound exhibits a spontaneous magnetization below Tc = 54 K. Further magnetization measurements on the field dependence reveal it to be a ferrimagnet where all of the MnII ions are antiparallel to all the W(V) ions.     

Ferro- and antiferromagnetic interactions in face-sharing trioctahedral Ni(II)Mn(II)Ni(II) and Ni(II)Fe(III)Ni(II) complexes with the same 1-5/2-1 spin system

Two heterotrinuclear complexes, [Mn(II)(Ni(II)L)2].2CH3OH (where H3L = 1,1,1-tris(N-salicylideneaminomethyl)ethane) and [Fe(III)(Ni(II)L)2]NO3.C2H5OH, consisting of three face-sharing octahedra have been prepared; although these complexes have closely related structures and have the same 1-5/2-1 spin system, they show completely different magnetic interactions between the adjacent metal ions: ferromagnetic (Ni(II)-Mn(II)) and antiferromagnetic (Ni(II)-Fe(III)).     

Redox-switchable conjugated bimetallic ruthenium(II) complexes

The conjugated bimetallic ruthenium(II) complex composed of 1,4-phenylenediamine as a bridging ligand was synthesized by photo-irradiation to show redox-switching of the emission properties of the terminal Ru(II) units depending on the redox state of the π-conjugated bridging spacer.     

Cyano-bridged bimetallic complexes of copper(II) with tetracyanonickelate(II). Crystal structure of [Cu(dpt)Ni(CN)4]

Five new complexes of composition [Cu(dpt)Ni(CN)₄] (1) (dpt=dipropylenetriamine), [Cu(dien)Ni(CN)₄]·2H₂O (2) (dien=diethylenetriamine), [Cu(N,N′-dimeen)Ni(CN)₄]·H₂O (3) (N,N′-dimeen=N,N′-dimethylethylenediamine), [Cu(N,N-dimeen)Ni(CN)₄]·H₂O (4) (N,N-dimeen=N,N-dimethylethylenediamine) and [Cu(trimeen)Ni(CN)₄] (5) (trimeen=N,N,N′-trimethylethylenediamine) have been obtained by the reactions of the mixture of Cu(ClO₄)₂·6H₂O, appropriate amine and K₂[Ni(CN)₄] in water and have been characterized by IR and UV–Vis spectroscopies and magnetic measurements. The crystal structure of [Cu(dpt)Ni(CN)₄] (1) has been determined by single-crystal X-ray analysis. The structure of 1 consists of a one-dimensional polymeric chain ---Cu(dpt)---NC---Ni(CN)₂---CN---Cu(dpt)--- in which the Cu(II) and Ni(II) atoms are linked by CN groups. The nickel atom is four coordinate with four cyanide-carbon atoms (two cyano groups are terminal and two cyano groups (in cis fashion) are bridged) in a square-planar arrangement and the copper atom is five coordinate with two cyanide-nitrogen and three dpt-nitrogen atoms, in a distorted square-pyramidal arrangement. The temperature dependence of magnetic susceptibility (2–300 K) was measured for compound 1. The magnetic investigation showed the presence of a very weak antiferromagnetic interaction (J=−0.16 cm⁻¹) between the copper atoms within each chain through the diamagnetic Ni(CN)₄ ²⁻ ions.