Cyano-bridged structures based on [MnIIN3O2-macrocycle)]2+: a synthetic, structural, and magnetic study

Reactions between the complex [MnII(L)]2+, where L is a N3O2 macrocyclic ligand, and different cyanometalate precursors such as [M(CN)n]m- (M(III) = Cr, Fe; M(II) = Fe, Ni, Pd, Pt) lead to cyano-bridged molecular assemblies exhibiting a variety of structural topologies. The reaction between [MnII(L)]2+ and [FeII(CN)6]4- forms a trinuclear complex with formula [(MnII(L)(H2O))2(FeII(micro-CN)2(CN)4)] x 2MeOH x 10H2O (1) which crystallizes in the triclinic space group P1. The reaction between [MnII(L)]2+ and [M(II)(CN)4]2-, where M(II) = Ni (2), Pd (3), Pt (4), gives rise to three isostructural linear chain compounds with stoichiometry [(MnII(L))(M(II)(micro-CN)2(CN)2)]n and which crystallize in the monoclinic space group C2/c. The self-assembly between [MnII(L)]2+ with [M(III)(CN)6]3-, where M(III) = Cr (5), Fe (6, 7, 8), forms three types of compounds. Compounds 5 and 6 are isostructural (monoclinic, space group P2(1)/n), and the structures comprise anionic linear chains [(MnII(L))(M(III)(micro-CN)2(CN)4)]n(n-) with cationic trinuclear complexes [(MnII(L)(H2O))2(M(III)(micro-CN)2(CN)4)]+ as counterions. Using an excess of K3[FeIII(CN)6], an analogous compound to 6 but with K+ as counterion is obtained (7), which crystallizes in the triclinic space group P1. Compound 8 consists of 2-D layers with formula [(MnII(L))3(FeIII(micro-CN)4(CN)2)(FeIII(micro-CN)2(CN)4)]n x 2nMeOH; it crystallizes in the monoclinic space group P2(1)/n. The magnetic properties were investigated for all samples. In particular, compound 5, which shows antiferromagnetic exchange interactions between Mn(II) and Cr(III) ions through cyanide bridging ligands, has been studied in detail; the magnetic exchange parameter amounts to J = -7.5(7) cm(-1). Compound 8 shows a magnetically ordered phase below 6.4 K which is confirmed by M?ssbauer spectroscopy; two hyperfine split spectra were observed below Tc from which IJI values of 2.1 and 1.6 cm(-1) could be deduced.     

Crystal structures and magnetic properties of two low-dimensional materials constructed from [Mn(III)(salen)H2O]+ and [M(CN)8](3-/4-) (M = Mo or W) precursors

The syntheses, X-ray structures, and magnetic behaviors of two new cyano-bridged assemblies, the molecular [Mn(III)(salen)H2O]3[W(V)(CN)8].H2O (1) and one-dimensional [Mn(salen)(H2O)2]2[[Mn(salen)(H2O)][Mn(salen)]2[Mo(CN)(8)]].0.5ClO4.0.5OH.4.5H2O (2), are presented. Compound 1 crystallizes in the monoclinic system, has space group P2(1)/c, and has unit cell constants a = 13.7210(2) A, b = 20.6840(4) A, c = 20.6370(2) A, and Z = 4. Compound 2 crystallizes in the triclinic system, has space group P, and has unit cell dimensions a = 18.428(4) A, b = 18.521(3) A, c = 18.567(4) A, and Z = 2. The structure of 1 consists of the asymmetric V-shaped Mn-NC-W-NC-Mn-O(phenolate)-Mn molecules, where W(V) coordinates with [Mn(salen)H2O] and singly phenolate-bridged [Mn(salen)H2O]2 moieties through the neighboring cyano bridges. The [W(V)(CN)8]3- ion displays distorted square-antiprism geometry. The structure of 2 consists of the cyano-bridged [Mn3(III)Mo(IV)]n- repeating units linked by double phenolate bridges into one-dimensional zigzag chains. The Mn(III) centers are bound to Mo(IV) of square-antiprism geometry through the neighboring cyano bridges. The magnetic studies of 1 reveal the antiferromagnetic intramolecular interactions through the CN and phenolate bridges and the relatively weak intermolecular interactions. Compound 1 becomes antiferromagnetically ordered below TN = 4.6 K. The presence of the magnetic anisotropy is documented with the MH measurements carried out for both polycrystalline and single-crystal samples. At T = 1.9 K, the spin-flop transition is observed in the field of 18 kOe applied parallel to the bc plane, which is the easy plane of magnetization. Field dependence of magnetization of 1 shows field-induced metamagnetic behavior from the antiferromagnetic ground state of ST = 3/2 to the state of ST = 5/2. The magnetic properties of 2 indicate a weak antiferromagnetic interaction between Mn(III) centers in double-phenolate-bridged [Mn(III)(salen)]2 dinuclear subunits and a very weak ferromagnetic interaction between them through the diamagnetic [Mo(IV)(CN)8]4- spacer.     

Manganese(II) o ctacyanotungstate(V)-based magnet containing a noncoordinated aromatic molecule

We have prepared a pillared layer magnetic material containing a noncoordinated aromatic molecule, [{MnII(pyrimidine)(H2O)}2{MnII(H2O)2}{WV(CN)8}2](pyrimidine)2.2H2O. This compound has one-dimensional channels (6.2 x 2.1 A) that are occupied by noncoordinated pyrimidine. The magnetization versus temperature plots showed the magnetic phased transition temperature (TC) was 47 K. The magnetization versus external magnetic field plots showed that the saturation magnetization (MS) value was 13.0 muB at 2 K. This MS value indicates that an antiferromagnetic interaction operates between the WV (S = 1/2) and MnII (S = 5/2) ions. The magnetic hysteresis loop showed that the coercive field (HC) was 17 G at 2 K.     

Two WV-MnIII bimetallic assemblies built by octacyanotungstate(v) and MnIII Schiff bases: molecular structures and a spin-flop transition

Two W(V)-Mn(III) bimetallic compounds, [Mn(Cl-salmen)(H(2)O)2]{[Mn(5-Clsalmen)(H(2)O)]2[W(CN)8].2H(2)O (1.2H(2)O) [5-Clsalmen = N,N'-(1-methylethylene)bis(5-chlorosalicylideneiminato) dianion], which contains trinuclear Mn(2)W and isolated Mn(III) moieties, and [Mn(3-MeOsalcy)(H(2)O)2]3[W(CN)(8)].2H(2)O (2.2H(2)O) [3-MeOsalcy = N,N'-(trans-1,2-cyclohexanediylethylene)bis(3-methoxysalicylideneiminato) dianion] molecules were prepared in redox processes and characterized using X-ray analysis and magnetic measurements. Compound 1 is composed of the {[Mn(5-Clsalmen)(H(2)O)]2[W(CN)8]}- trimer, in which two CN groups among eight in [W(CN)8](3-) bridge W(5+) and two Mn(3+) ions and the remaining CN ligands are hydrogen-bonded to water molecules or unbound, and the [Mn(Cl-salmen)(H(2)O)2]+ cation. Subsequently, two water molecules of the isolated cation are subject to hydrogen bonds. For 2, there are no covalent bonds among the subunits and six serial stacks of [Mn(3-MeOsalcy)(H(2)O)2]+ units are all hydrogen-bonded. The many hydrogen bonds found in both complexes eventually lead to three-dimensional networks. The magnetic studies for 1 reveal that antiferromagnetic interactions (J = -5.4 cm(-1)) between W(V) and Mn(III) centers within the trimer are transmitted via the bridging CN groups. Intermolecular antiferromagnetic couplings (zJ' = -0.2 cm(-1)) are also observed. The static and dynamic magnetic data of 1 demonstrate the existence of a field-induced spin-flop transition occurring among the clusters and monomeric molecules.     

Ln(terpy)]3+ (Ln = Sm, Gd) entity forms isolated magnetic chains with [W(CN)8]3-

The reaction between Ln(NO3)3*xH2O, Cs3[W(V)(CN)8]*H2O and 2,2':6',2'-terpyridine (terpy) leads to the original isomorphous cyano-bridged [Ln(III)(terpy)(DMF)4][W(V)(CN)8] *6H2O [Ln = Gd (1), Sm (2)] 1-D chains. The crystal structures of {Ln(III)W(V)} chains and consist of alternating {[W(CN)8]} and {[Ln(terpy)]} building blocks. The neighbouring 1-D chains are weakly linked through pi-pi stacking interactions of the aromatic rings leading to 2-D supramolecular layers. The layers are linked through hydrogen bonds between H2O molecules and terminal cyano ligands. Magnetic studies revealed a weak antiferromagnetic coupling (J = -2.3(2) K) within the {Gd(III)W(V)} chains in . The positive effective coupling constant J = +2.0(5) K between the total angular momentum of the Sm(III) centre and the spin of the W(v) ion is equivalent to an antiferromagnetic character of the spin coupling between both centres in the {Sm(III)W(V)} chains of 2. The magnetic measurements suggest that they display an isolated magnetic chain behaviour.     

Variation of heterometallic structural motifs based on [W(CN)8]3- anions and Mn(II) ions as a function of synthetic conditions

Reactions of [W(CN)(8)](3-/4-) anions with complexes of Mn(2+) ion with tridentate organic ligand 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) lead to a series of heterobimetallic complexes. The crystal structures of these compounds are derived from the same basic structural fragment, namely a W(2)Mn(2) square constructed of alternating cyanide-bridged W and Mn ions. In [Mn(II)(tptz)(OAc)(H(2)O)(2)](2){[Mn(II)(tptz)(MeOH)(1.58)(H(2)O)(0.42)](2)[W(V)(CN)(8)](2)}.5 MeOH.9.85 H(2)O (3), isolated molecular squares are co-crystallized with mononuclear cationic Mn(II) complexes. The structure of {[Mn(II)(tptz)(MeOH)](2)[W(IV)(CN)(8)].2 MeOH}(infinity) (4) is based on an infinite chain of vertex-sharing squares, while {[Mn(II) (2)(tptz)(2)(MeOH)(3)(OAc)][W(V)(CN)(8)].3.5 MeOH0.25 H(2)O}(infinity) (5) and {[Mn(II) (2)(tptz)(2)(MeOH)(3)W(V)(CN)(8)][Mn(II)(tptz)(MeOH)W(V)(CN)(8)].2 H(2).OMeOH}(8) (7) are derived from such an infinite chain by removing one of the W-C[triple bond]N-Mn linkages in each of the squares. The decanuclear cluster [Mn(II) (6)(tptz)(6)(MeOH)(4)(DMF)(2)W(V) (4)(CN)(32)].8.2 H(2)O.2.3 MeOH (6) is a truncated version of structure 4 and consists of three vertex-sharing W(2)Mn(2) squares. The structure of [Mn(II)(tptz)(MeOH)(NO(3))](2)[Mn(II)(tptz)(MeOH) (DMF)](2)[W(V)(CN)(8)](2).6 MeOH (8) consists of a hexanuclear cluster, in which the central W(2)Mn(2) square is extended by two Mn side-arms attached via CN(-) ligands to the W corners of the square. The magnetic behavior of these heterobimetallic complexes (except for 4) is dominated by antiferromagnetic coupling between Mn(II) and W(V) ions mediated by cyanide bridges. Compounds 3, 6, and 8 exhibit high spin ground states of S=4, 13, and 9, respectively, while 5 and 7 exhibit behavior typical of a ferrimagnetic chain with alternating spin centers. Complex 4 contains diamagnetic W(IV) centers but holds promise as a potential photomagnetic solid.     

Synthesis,crystal structures,and magnetic properties of two cyano-bridged tungstate(V)-manganese(II) bimetallic magnets

The reaction of manganese acetate with octacyanotungastate in an aqueous solution of concentrated acetic acid gives two new three-dimensional cyano-bridged manganese(II)-tungstate(V) bimetallic assemblies, [Mn(II)(2)(H(2)O)(2)(CH(3)COO)][W(V)(CN)(8)].2H(2)O (1) (tetragonal space group I4/mcm, a = b = 11.9628(9) A, c = 13.367(2) A, and Z = 4) and Cs(I)(0.5)Mn(II)(2)[W(V)(CN)(8)](CH(3)CO(2))(1.5).H(2)O (2) (monoclinic space group C2/c, a = 16.274(2) A, b = 22.948(6) A, c = 13.196(1) A, beta = 128.040(6) degrees, and Z = 8). In complex 1, W(V)(CN)(8) adopts a square antiprismatic geometry, and each CN group coordinates to the Mn(II) ions forming W-Mn(4)-W-Mn(4)-...columnar linkages where four sites on the Mn(II) ion with octahedral geometry are occupied by CN groups. The columns are parallel and interlock, yielding a network structure. Complex 2 contains two different coordination geometries for W(V)(CN)(8), namely, square antiprismatic and dodecahedral. The columnar structures appear also in 2, where the Mn(II) ions in two different environments provide three and four coordinated sites to the CN groups. The columns are bridged by both dodecahedral W(V)(CN)(8) groups and acetates. Cs ions were intercalated in the lattice by the formation of short attractive contacts with the acetates. The field-cooled magnetization, ac susceptibility, and the field dependence of magnetization measurements show that both 1 and 2 are ferrimagnets with ordering temperatures 40 and 45 K, respectively. The investigation of the magnetostructural correlation shows that the ferrimagnetic ordering in 1 and 2 are attributed to the dominant antiferromagnetic exchange pathways d(z)2(W)-d(x')(y')(Mn) and d(x)2(-y)2(W) - d(x')(y')(Mn).     

Crystal structures and magnetic properties of two octacyanotungstate(IV) and (V)-cobalt(II) three-dimensional bimetallic frameworks

The synthesis, X-ray structures, and magnetic behavior of two new, three-dimensional compounds [W(IV)[(mu-CN)(4)Co(II)(H(2)O)(2)](2).4H(2)O](n) (1) and [[W(V)(CN)(2)](2)[(mu-CN)(4)Co(II)(H(2)O)(2)](3).4H(2)O](n) (2) are presented. Compound 1 crystallizes in the tetragonal system, space group I4/m with cell constants a = b = 11.710(3) A, c = 13.003(2) A, and Z = 4, whereas 2 crystallizes in the orthorhombic system, space group Cmca with cell constants a = 13.543(5) A, b = 16.054(6) A, c = 15.6301(9) A, and Z = 4. The structure of 1 shows alternating eight-coordinated W(IV) and six-coordinated Co(II) ions bridged by single cyanides in a three-dimensional network. The geometry of each [W(IV)(CN)(8)](4-) entity in 1 is close to a square antiprism. Its eight cyanide groups are coordinated to Co(II) ions which have two coordinated water molecules in trans position. The structure of 2 consists of alternating eight-coordinated W(V) and six-coordinated Co(II) ions linked by single cyanide bridges in a three-dimensional network. Each [W(V)(CN)(8)](3-) unit shows a geometry close to a square antiprism. Only six of its eight cyanide groups are coordinated to Co(II) ions while the other two are terminal. The Co(II) ion in 2 has the same CoN(4)O(2) environment as in 1. The magnetic behavior of 1 is that of magnetically isolated high spin Co(II) ions (S(Co) = 3/2), bridged by the diamagnetic [W(IV)(CN)(8)](3-) units (S(W(IV)) = 0). The magnetic behavior of 2, where the high spin Co(II) ions are bridged by the paramagnetic [W(V)(CN)(8)](3-) units [S(W(V)) = 1/2], is that of ferromagnetically coupled Co(II) and W(V) giving rise to an ordered ferromagnetic phase below 18 K. The magnetic properties of 1 are used as a blank to extract the parameters that are useful to analyze the magnetic data of compound 2.     

Octacyanotungstate(V)-based magnetic complex consisting of dimeric Mn(2) and tetrameric Mn(2)W(2)

A novel zero-dimensional (0D) octacyanotungstate(V)-manganese(II) bimetallic assembly, {[MnII(bipy)2]2(ox)}.{[MnII(bipy)2W(CN)8]2}.4H2O (1) (bipy = 2,2'-bipyridine, ox = C2O42-), was synthesized in methanol solution containing oxalic acid. X-ray analysis shows 1 is crystallized in monoclinic crystal system with C2/c space group and composed of two components of a dimeric Mn2 cation and a quadrate tetrameric Mn2W2 anion. The Mn2 and Mn2W2 moieties are connected by their respective pi-pi stacking to yield the alternative 2D layers, and the 2D layers are linked by hydrogen bonding to form a 3D network. The investigation of the magnetostructural correlation reveals that cyanide and oxalate bridges mediate weak intracluster antiferromagnetic coupling between Mn and W ions and between Mn ions, respectively. Further magnetic measurements and analysis show the spin glasses and intercluster ferromagnetic interaction exist in complex 1.     

An unprecedented copper(I,II)-octacyanotungstate(V) 2-D network: crystal structure and magnetism of [CuII(tren)]{CuI[W(V)(CN)8]} . 1.5H2O

A novel two-dimensional cyanide-bridged polymer [CuII(tren)]{CuI[W(V)(CN)8]} . 1.5H2O (tren = tris(2-aminoethyl)amine) formed via the simultaneous in situ metal-ligand redox reaction of [Cu(tren)(OH2)]2+ and self-assembly with [W(V)(CN)8]3- consists of a {CuI[W(V)(CN)8]} square grid built of CuI centres of tetrahedral geometry coordinatively saturated by CN bridges and [W(V)(CN)8]3- capped by [CuII(tren)]2+ moieties; it exhibits ferromagnetic coupling J1 = +5.8(1) cm(-1) within the CuII-W(V) dinuclear subunits and weak antiferromagnetic coupling J2 = -0.03(1) cm(-1) between them through diamagnetic CuI spacers.     

Near-infrared luminescent and magnetic cyano-bridged coordination polymers Nd(phen)n(DMF)m[M(CN)8] (M = Mo, W)

New cyano-bridged coordination polymers [Nd(phen)(2)(DMF)(2)(H(2)O)Mo(CN)(8)]·2H(2)O (1) and [Nd(phen)(DMF)(5)M(CN)(8)]·xH(2)O [M = Mo (2), W (3); phen = 1,10-phenanthroline] have one-dimensional structures with variable number of phenanthroline ligands. Compounds exhibit photoluminescence in the near-infrared region and ferromagnetic Nd(3+)-M(5+) interactions.     

High Tc ferrimagnetic organic-inorganic hybrid materials with MnII-L-MnII and MnII-NC-NbIV linkages (L=pyrazine, pyrazine-N,N'-dioxide, bipyrimidine)

A series of heterobimetallic, cyano-bridged 3D inorganic-organic hybrid networks with MnII-L-MnII and MnII-NC-NbIV linkages are reported. Reaction of [Mn(H2O)6]2+ with [Nb(CN)8]4- in the presence of organic linker L (pyrazine (pyz), pyrazine-N,N'-dioxide (pzdo), and 2,2'-bipyrimidine (bpym)) in H2O affords {MnII2(pz)2(H2O)4[NbIV(CN)8]}.pz.3H2O (1), {MnII2(pzdo)(H2O)4[NbIV(CN)8]}.5H2O (2), and {MnII2(bpym)(H2O)2[NbIV(CN)8]} (3), respectively. 1-3 were examined by X-ray crystallography and vibrational and magnetochemical studies. 1 is characterized by the coexistence of 3D inorganic cyano-bridged and 1D organic [Mn-(micro-pyz)]n2n+ sublattices along with the presence of monocoordinated and crystallization molecules of pyrazine. Assemblies 2 and 3 exhibit dimeric {MnII2-(micro-L)}4+ coordination motifs. The magnetic behavior of heterobimetallic 1-3 complexes is dominated by antiferromagnetic coupling between MnII and NbIV centers mediated by cyano bridges, resulting in long-range ferrimagnetic ordering with a high TC of 27 (1), 37 (2), and 50 K (3). The magneto-structural correlation leads to the conclusion that the magnitude of TC is related to the type of coordination polyhedra of [Nb(CN)8] moieties (SAPR (1), intermediate between SAPR and DD (2), and DD (3)), the relative number of cyano bridges per Mn2Nb unit, and coexistence of inorganic and organic connectivity. FC/ZFC responses appear to be sensitive to the degree of organic connectivity. The discussion of magneto-structural correlation is based on the spin-density properties of adequate heterobimetallic systems containing octacyanometalates.     

The role of carboxylate ligands in two novel cyanido-bridged 2D coordination networks Cu(II)-W(V) and Mn(II)-Nb(IV)

We report on the synthesis, molecular structure and magnetic properties of two novel coordination polymers: [{Cu(II)(4)(pic)(2)(H(2)O)(2)(MeOH)}{W(V)(CN)(8)}(2)]·MeOH·4H(2)O (1) and [{Mn(II)(3)(HCOO)(2)(H(2)O)(4)}{Mn(II)(H(2)O)(3)(HCONH(2))}(2){Nb(IV)(CN)(8)}(2)]·4HCONH(2)·2H(2)O (2). The single-crystal X-ray diffraction analysis of 1 shows that its molecular structure can be interpreted as a cyanido bridged (3,4,7)-connected 2D bilayer built of two different subnets sharing the tungsten centers. The magnetic measurements suggest that the system reveals long-range ferromagnetic ordering between Cu(II) and W(V) centers below 13.4 K. The molecular structure of (2) reveals a 2D topology of layers built of cyanido and formato bridging ligands. The system reveals ferrimagnetic behavior with a critical temperature at 17.8 K.     

Synthesis and Crystal Structure of aNovelPolythiotungstate Compound[PPh4]2[（S）2W（μ—S）2（O）W（THF）（μ—S）2W（S）2]

1 INTRODUCTION Polythiotungstate complexes can be prepared from the protonation of one sulfur atom of [WS4]2－ and subsequent intramolecular redox reactions[1,2]. For example, [(S)2W(m-S)2W(m-S)2W(S)2]2 was formed by the acidification of a diluted aqueous solution of (NH4)2[WS4] with dilute H2SO4[3]. When a diluted aqueous solution containing [WS4]2 was acidified with 0.1mol/L HCl, [(S)2W(m-S)2(O)- W(H2O)(m-S)2W(S)2]2 was formed[4]. [(S)2W- (m-S)2(S)W(m-S)2W(S)2]2 was form…     

Synthesis and structural characterization of bi- and trimetallic octacyanometalate(IV) complexes: [Delta,Lambda-MII(en)3][cis-MII(en)2(OH2)][MIV(CN)8].2H2O and [cis-MII(en)2(OH2)]2[(mu-NC)2MIV(CN)6].4H2O (MII = Mn, Co, Ni; MIV = Mo, W)

Treatment of [M(II)(en)(3)][OTs](2) or methanolic ethylenediamine solutions containing transition metal p-toluenesulfonates (M(II) = Mn, Co) with aqueous K(4)M(IV)(CN)(8).2H(2)O or Cs(3)M(V)(CN)(8) (M(IV) = Mo, W; M(V) = Mo) affords crystalline clusters of [M(II)(en)(3)][cis-M(II)(en)(2)(OH(2))(mu-NC)M(IV)(CN)(7)].2H(2)O (M(IV) = Mo; M(II) = Mn, 1; Ni, 5; M(IV) = W; M(II) = Mn, 2; Ni, 6) and [cis-M(II)(en)(2)(OH(2))](2)[(mu-NC)(2)M(IV)(CN)(6)].4H(2)O (M(IV) = Mo; M(II) = Co, 3; Ni, 7; M(IV) = W; M(II) = Co, 4) stoichiometry. Each cluster contains cis-M(II)(en)(2)(OH(2))(mu-NC)(2+) units that likely result from dissociative loss of en from [M(II)(en)(3)](2+), affording cis-M(II)(en)(2)(OH(2))(2)(2+) intermediates that are trapped by M(IV)(CN)(8)(4-).     

Encapsulation of cyanometalates by a tris-macrocyclic ligand tricopper(II) complex: syntheses, structural variation, and magnetic exchange coupling pathways

The reaction of [M(CN)(6)](3-) (M = Cr(3+), Mn(3+), Fe(3+), Co(3+)) and [M(CN)(8)](4-/3-) (M = Mo(4+/5+), W(4+/5+)) with the trinuclear copper(II) complex of 1,3,5-triazine-2,4,6-triyltris[3-(1,3,5,8,12-pentaazacyclotetradecane)] ([Cu(3)(L)](6+)) leads to partially encapsulated cyanometalates. With hexacyanometalate(III) complexes, [Cu(3)(L)](6+) forms the isostructural host-guest complexes [[[Cu(3)(L)(OH(2))(2)][M(CN)(6)](2)][M(CN)(6)]][M(CN)(6)]30 H(2)O with one bridging, two partially encapsulated, and one isolated [M(CN)(6)](3-) unit. The octacyanometalates of Mo(4+/5+) and W(4+/5+) are encapsulated by two tris-macrocyclic host units. Due to the stability of the +IV oxidation state of Mo and W, only assemblies with [M(CN)(8)](4-) were obtained. The Mo(4+) and W(4+) complexes were crystallized in two different structural forms: [[Cu(3)(L)(OH(2))](2)[Mo(CN)(8)]](NO(3))(8)15 H(2)O with a structural motif that involves isolated spherical [[Cu(3)(L)(OH(2))](2)[M(CN)(8)]](8+) ions and a "string-of-pearls" type of structure [[[Cu(3)(L)](2)[M(CN)(8)]][M(CN)(8)]](NO(3))(4) 20 H(2)O, with [M(CN)(8)](4-) ions that bridge the encapsulated octacyanometalates in a two-dimensional network. The magnetic exchange coupling between the various paramagnetic centers is characterized by temperature-dependent magnetic susceptibility and field-dependent magnetization data. Exchange between the CuCu pairs in the [Cu(3)(L)](6+) "ligand" is weakly antiferromagnetic. Ferromagnetic interactions are observed in the cyanometalate assemblies with Cr(3+), exchange coupling of Mn(3+) and Fe(3+) is very small, and the octacoordinate Mo(4+) and W(4+) systems have a closed-shell ground state.     

Microwave-assisted construction of ferromagnetic coordination polymers of [W(V)(CN)8]3- with Cu(II)-pyrazole synthons

The microwave-mediated self-assembly of [W(V)(CN)(8)](3-) with Cu(II) in the presence of pyrazole ligand resulted in the formation of three novel assemblies: Cu(II)(2)(Hpyr)(5)(H(2)O)[W(V)(CN)(8)](NO(3))·H(2)O (1), {Cu(II)(5)(Hpyr)(18)[W(V)(CN)(8)](4)}·[Cu(II)(Hpyr)(4)(H(2)O)(2)]·9H(2)O (2), and Cu(II)(4)(Hpyr)(10)(H(2)O)[W(V)(CN)(8)](2)(HCOO)(2)·4.5H(2)O (3) (Hpyr =1H-pyrazole). Single-crystal X-ray structure of 1 consists of cyanido-bridged 1-D chains of vertex-sharing squares topology. The structure of 2 reveals 2-D hybrid inorganic layer topology with large coordination spaces occupied by {Cu(Hpyr)(2)(H(2)O)(4)}(2+) ions. Compound 3 contains two types of cyanido-bridged 1-D chains of vertex-sharing squares linked together by formate ions in two directions forming hybrid inorganic-organic 3-D framework (I(1)O(2)). The magnetic measurements for 1-3 reveal a weak ferromagnetic coupling through Cu(II)-NC-W(V) bridges.     

An S = 2 cyanide-bridged trinuclear Fe(III)2Ni(II) single-molecule magnet

Treatment of [NEt4][(pzTp)Fe(III)(CN)3] (1) with Ni(II)(OTf)2 (OTf = trifluoromethanesulfonate) and 1,5,8,12-tetraazadodecane (L) affords {[(pzTp)Fe(III)(CN)3]2[Ni(II)L]} x 1/2MeOH (2), while 2,2'-bipyridine (bipy) affords {[(pzTp)Fe(III)(CN)3]2[Ni(II)(bipy)2]} x 2 H2O (3). Magnetic measurements indicate that 2 and 3 have S = 2 ground states and that 3 exhibits slow relaxation of the magnetization above 2 K.     

Synthesis and structure of two tetranuclear osmium carbonyl isotopomers: a crystallographic isotope effect

A synthetic route to [Os4(mu-H)(mu-OH)(mu-CO)(CO)12] ( 1) has been devised through the activation of [Os4(CO)14] with Me3NO. The pyrolysis and photolysis of the reactant in the presence of a trace amount of water produces 1 in low yield. The solid-state structure of [Os4(mu-H)(mu-OH)(mu-CO)(CO)12 x H2O] (1 x H2O) reveals a butterfly Os4 skeleton with bridging H, OH and CO ligands as well as hydrogen-bonded molecules of water in the crystal lattice. A low-temperature 13C{1H} NMR spectroscopic study revealed a merry-go-round exchange of CO ligands around the Os3 plane containing the asymmetric bridging CO. The exposure of 1 x H2O to D2O yielded [Os4(mu-H)(mu-OD)(mu-CO)(CO)12]2. Although the solid-state, intramolecular structure of 2 closely matched that of 1 x H2O, the intermolecular structure did not: its crystal lattice contained no water of crystallization, a previously unreported crystallographic isotope effect.     

W-knotted chain {[Cu(II)(dien)]4[W(V)(CN)8]}(5+)∞: synthesis, crystal structure, magnetism, and theory

The self-assembly of [Cu(II)(dien)(H(2)O)(2)](2+) and [W(V)(CN)(8)](3-) in aqueous solution leads to the formation (H(3)O){[Cu(II)(dien)](4)[W(V)(CN)(8)]}[W(V)(CN)(8)](2)·6.5H(2)O (1). The crystal structure of 1 consists of an unprecedented {[Cu(II)(dien)](4)[W(V)(CN)(8)]}(5+)(∞) chain of (2,8) topology, nonbridging [W(CN)(8)](3-) anions, and crystallization water molecules. The analysis of magnetic behavior of 1 was performed by the density functional theory (DFT) method and magnetic susceptibility measurements. The DFT broken symmetry approach gave two J(CuW) coupling constants: J(ax) = +2.9 cm(-1) assigned to long and strongly bent W-CN-Cu linkage, and the J(eq) = +1.5 cm(-1) assigned to short and less bent W-CN-Cu linkage, located at the axial and the equatorial positions of square pyramidal Cu(II) centers, respectively, in the hexanuclear {W(2)Cu(4)} chain subunit. The dominance of weak-to-moderate ferromagnetic coupling within the chain was confirmed by magnetic calculations. Zero-field susceptibility of the full chain segment {WCu(4)}(n) was calculated by a semiclassical analytical approach assuming that only one W(V) out of five ? spins of the chain unit WCu(4) is treated as a classical commuting variable. The calculation of the field dependence of the magnetization was performed separately by replacing the same spin with the Ising variable and applying the standard transfer matrix technique. The intermolecular coupling between the chain segments and off-chain [W(CN)(8)](3-) entities was resolved using the mean-field approximation set to be of antiferromagnetic character. The magnetic coupling parameters are compared with those of other low dimensional {Cu(II)-[M(V)(CN)(8)]} systems.