Vibrational spectra of MII3Pb(P2O7)2 (MII = Ni,Co)

Raman and IR spectra of polycrystalline Ni₃Pb(P₂O₇)₂ and Co₃Pb(P₂O₇)₂ have been recorded and analyzed. The internal modes are assigned in terms of PO₃ and POP vibrations. The results point to a bent POP bridge configuration in Co₃Pb(P₂O₇)₂ as in Ni₃Pb(P₂O₇)₂. In the cobalt compound, the P₂O⁴⁻₇ ions are distorted. Non-coincidence of the majority of the Raman and IR bands confirms a centrosymmetric structure for Ni₃Pb(P₂O₇)₂, and Co₃Pb(P₂O₇)₂. The POP bridge angle is slightly higher in the cobalt compound than in the nickel compound.     

Syntheses,Crystal Structures and Properties of the Tetrametaphosphimates MII2(PO2NH)4 · 8 H2O with MII = Mg,Mn, Co and Zn

Mg₂(PO₂NH)₄ · 8 H₂O ( 1 ), Mn₂(PO₂NH)₄ · 8 H₂O ( 2 ), Co₂(PO₂NH)₄ · 8 H₂O ( 3 ) and Zn₂(PO₂NH)₄ · 8 H₂O ( 4 ) were obtained as microcrystalline powders by combining aqueous solutions of K₄(PO₂NH)₄ · 4 H₂O and MX₂ · y H₂O (M = Mg, Mn, Co, Zn; X = Cl, NO₃). Single crystals were obtained by crystallization in gelatine gels in U‐tubes or test‐tubes. 2 and 4 were characterized by thermogravimetry and 4 was additionally characterized by temperature dependend in situ powder diffractometry. The structures of 1 , 2 , 3 and 4 were found to be isotypic and were solved by single‐crystal X‐ray methods: P 2₁/c, Z = 2 ( 1 : a = 645.4(2), b = 1050.1(2), c = 1283.3(3) pm, β = 104.66(3)°; 2 : a = 648.7(2), b = 1063.1(2), c = 1310.8(3) pm, β = 103.93(3)°; 3 : a = 643.3(2), b = 1049.0(2), c = 1286.7(3) pm, β = 104.28(3)°; 4 : a = 644.18(5), b = 1049.22(7), c = 1282.43(8) pm, β = 104.122(6)°). The structure is composed of MO₆ octahedra and (PO₂NH)₄^4— anions. The P₄N₄ rings of the (PO₂NH)₄^4— anions exhibit a slightly distorted chair conformation, which is supported by IR data and has been described by torsion angles, Displacement Asymmetry Parameters and Puckering Parameters. Via M²⁺ ions and hydrogen bonds, the tetrametaphosphimate anions are connected forming layers perpendicular to [100]. These layers are connected by hydrogen bonds.     

[CrIII8MII6]12+ Coordination Cubes (MII=Cu, Co)

[Cr^III₈M^II₆]¹²⁺ (M^II=Cu, Co) coordination cubes were constructed from a simple [Cr^IIIL₃] metalloligand and a “naked” M^II salt. The flexibility in the design proffers the potential to tune the physical properties, as all the constituent parts of the cage can be changed without structural alteration. Computational techniques (known in theoretical nuclear physics as statistical spectroscopy) in tandem with EPR spectroscopy are used to interpret the magnetic behavior.     

Metal–Organic Perovskites: Synthesis,Structures, and Magnetic Properties of [C(NH2)3][MII(HCOO)3] (M=Mn,Fe, Co,Ni, Cu,and Zn; C(NH2)3= Guanidinium)

We report the synthesis, crystal structures, and spectral, thermal, and magnetic properties of a family of metal–organic perovskite ABX₃, [C(NH₂)₃][M^II(HCOO)₃], in which A=C(NH₂)₃ is guanidinium, B=M is a divalent metal ion (Mn, Fe, Co, Ni, Cu, or Zn), and X is the formate HCOO^?. The compounds could be synthesized by either diffusion or hydrothermal methods from water or water‐rich solutions depending on the metal. The five members (Mn, Fe, Co, Ni, and Zn) are isostructural and crystallize in the orthorhombic space group Pnna, while the Cu member in Pna2₁. In the perovskite structures, the octahedrally coordinated metal ions are connected by the anti–anti formate bridges, thus forming the anionic NaCl‐type [M(HCOO)₃]^? frameworks, with the guanidinium in the nearly cubic cavities of the frameworks. The Jahn–Teller effect of Cu²⁺ results in a distorted anionic Cu–formate framework that can be regarded as Cu–formate chains through short basal Cu? O bonds linked by the long axial Cu? O bonds. These materials show higher thermal stability than other metal–organic perovskite series of [AmineH][M(HCOO)₃] templated by the organic monoammonium cations (AmineH⁺) as a result of the stronger hydrogen bonding between guanidinium and the formate of the framework. A magnetic study revealed that the five magnetic members (except Zn) display spin‐canted antiferromagnetism, with a Néel temperature of 8.8 (Mn), 10.0 (Fe), 14.2 (Co), 34.2 (Ni), and 4.6 K (Cu). In addition to the general spin‐canted antiferromagnetism, the Fe compound shows two isothermal transformations (a spin‐flop and a spin‐flip to the paramagnetic phase) within 50 kOe. The Co member possesses quite a large canting angle. The Cu member is a magnetic system with low dimensional character and shows slow magnetic relaxation that probably results from the domain dynamics.     

Kristallstrukturbestimmungen an vier monoklinen Weberiten Na2MIIMIIIF7 (MII = Fe,Co; MIII = V,Cr)

Crystal Structure Determinations of Four Monoclinic Weberites Na₂M^IIM^IIIF₇ (M^II = Fe, Co; M^III = V, Cr) By solid state reaction of the binary fluorides single crystals of the following weberites were prepared and their monoclinic structure (space group C2/c, Z = 16) determined by X-ray methods: Na₂FeVF₇ (a = 1 271.0(3), b = 742.9(1), c = 2 471.6(5) pm, β = 100.03(3)°; R₁ = 0.043 (1 545 Reflexe); Fe? F = 203.8, V? F = 193.0 pm); Na₂FeCrF₇ (a = 1 262.5(3), b = 739.1(1), c = 2 460.5(5) pm, β = 99.93(3)°; R₁ = 0.029 (2 340); Fe? F = 203.6, Cr? F = 190.5 pm); Na₂CoVF₇ (a = 1 270.3(5), b = 739.1(3), c = 2 465.1(10) pm, β = 100.02(3)°; R₁ = 0.028 (2 250); Co? F = 201.6, V? F = 193.6 pm); Na₂CoCrF₇ (a = 1 257.8(3), b = 733.5(1), c = 2 441.5(5) pm, β = 99.64(3)°; R₁ = 0.030 (2 227); Co? F = 201.2, Cr? F = 190.2 pm). Concerning the above average distances within the distorted [MF₆] octahedra and the shape of [NaF₈] coordination details are given and discussed.     

Self-encapsulation of [MII(phen)2(H2O)2]2+ (M=Co, Zn) in one-dimensional nanochannels of [MII(H2O)6(BTC)2]4- (M=Co, Cu, Mn): a high HQ/CAT ratio catalyst for hydroxylation of phenols

Four novel three-dimensional (3D) microporous supramolecular compounds containing nanosized channels, namely, [Co(phen)2(H2O)2]2[Co(H2O)6].2BTC.21.5H2O (1), [Co(phen)2(H2O)2]2[Cu(H2O)6].2BTC.21.5H2O (2), [Co(phen)2(H2O)2]2[Mn(H2O)6].2BTC.18H2O (3), and [Zn(phen)2(H2O)2]2[Mn(H2O)6].2BTC.22.5H2O (4), were synthesized from 1,3,5-benzenetricarboxylate (BTC), 1,10-phenanthroline (phen), and the transition-metal salt(s) by self-assembly. Single-crystal X-ray structural analysis showed that the resulting 3D microporous supramolecular frameworks consist of a two-dimensional (2D) hydrogen-bonded host framework of [MII(H2O)6(BTC)2]4- (M=Co for 1, Cu for 2, Mn for 3, 4) with rectangular-shaped cavities containing [MII(phen)2(H2O)2]2+ (M=Co for 1-3, Zn for 4) guests. The guest complex is encapsulated in the 2D hydrogen-bonded host framework by hydrogen bonding and aromatic pi-pi stacking interactions, forming the 3D hydrogen-bonded framework. The catalytic activities of 1, 2, 3, and 4 were studied using hydroxylation of phenols with 30% aqueous H2O2 as a test reaction. The compounds displayed a good phenol conversion ratio and excellent channel selectivity in the hydroxylation reaction, with a maximum hydroquinone (HQ)/catechol (CAT) ratio of 3.9.     

Two New Trinuclear MII (M = Mn,Co) Complexes Based on 2,4‐Dichlorobenzoic Acid: Synthesis,Structures and Magnetic Properties

Two new isostructural complexes, [Mn₃(L)₆(bipy)₂] ( 1 ) and [Co₃(L)₆(bipy)₂] ( 2 ) (L = 2,4‐dichlorobenzoate, bipy = 2, 2′‐bipyridine) were synthesized under the hydrothermal conditions and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, EA (elemental analysis), and magnetic measurements. The two complexes are found to contain a trinuclear (M₃) unit that opens up a possibility of being magnetic materials. The magnetic measurements reveal that 1 exhibits the antiferromagnetic exchange interaction between metal ions and 2 presents a weak ferromagnetic interactions between the Co^II ions.     

Oxamido‐bridged N4 Macrocyclic Complexes CuII/MII/CuII (M = Mn,Co): Synthesis,Crystal Structures and Magnetic Properties

Two new oxamido‐bridged N₄ macrocyclic complexes [(CuL)₂Mn(C₂H₅OH)₂](ClO₄)₂ · 2C₂H₅OH ( 1 ) and [(CuL)₂Co‐(C₂H₅OH)₂](ClO₄)₂ · 2C₂H₅OH ( 2 ) (H₂L = 2,3‐dioxo‐5,6:14,15‐di‐benzo‐7,13‐diphenyl‐1,4,8,12‐tetraazacyclo‐pentadeca‐7,13‐diene) have been synthesized and structurally characterized by X‐ray crystallographic investigations. In the two complexes, all copper(II) ions adopt a slightly distorted square‐planar configuration and the central manganese(II) and cobalt(II) ions are set in a distorted octahedral coordination sphere, connected to the other CuL fragments through exo‐cis oxamido bridges. The analyses of the magnetic properties were carried out by means of the theoretical expression of the magnetic susceptibility deduced from the spin Hamiltonian ? = –2J?₁?₂, leading to J = –14.58 cm^–1 for complex 1 and J = –26.95 cm^–1 for complex 2 , respectively.     

Structures and spectra of Na(NH3) n=1,2

Geometric structures and the energies for the ground and several excited electronic states of a sodium atom bound with one or two ammonia molecules are presented. All self consistent field (SCF) calculations are performed with extended basis sets. Geometry optimization and one electron properties have been performed within the SCF approximation. Excited states have been calculated with the multi-configuration SCF (MCSCF) technique. This system may be viewed as a precursor to solvation in a macroscopic system. The excited state calculations provide important information for spectroscopic studies of these complexes.     

Syntheses, structures, and magnetic characterization of dicyanometalate(II) building blocks: [NEt4][(Tp*)MII(CN)2] [MII = Cr, Co, Ni; Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate

The syntheses and structures of three dicyanometalate(II) complexes, [NEt(4)][(Tp*)M(II)(CN)(2)].nMeCN.(1/2)Et(2)O (M(II) = Cr, 1, n = (1/2); Co, 2, n = 1; Ni, 3, n = 1) are described; magnetic studies indicate that 3 is diamagnetic while 1 and 2 are paramagnetic high- and low-spin S = 2 and (1/2) complexes, respectively.     

M(EDTA)2－ (M＝Co, Ni, Cu, Zn, Cd)电子结构和性质的密度泛函理论研究

在B3LYP/LanL2DZ水平上, 计算研究了Co^2＋, Ni^2＋, Cu^2＋, Zn^2＋, Cd^2＋与乙二胺四乙酸(EDTA)六配位模式下配合物的结构和性质. 除Cu(EDTA)^2－的M—O(5)受Jahn-Teller效应影响明显拉长外, 配位键长M—N(1)和M—O(5)按 Cu^2＋＜Ni^2＋＜Co^2＋＜Zn^2＋＜Cd^2＋的顺序依次增长, 配位键长M—O(3)按Cu^2＋＜Zn^2＋＜Ni^2＋＜Co^2＋＜Cd^2＋的次序依次增长. 自然键轨道(NBO)分析表明, 氮、氧的非键电子与金属空轨道的相互作用是配体与金属离子配位的主要作用方式. 通过对N(1)—C(7), N(1)—C(9), N(1)—C(15)键长和NAO键级的分析, 在分子水平上阐明了EDTA在与金属离子配位前后发生首步降解, 其产物存在差异的实验事实. 依据热力学原理并兼顾自洽反应场(SCRF)的IEFPCM模型, 我们设计了金属离子与EDTA在水溶液中的反应途径和热力学循环. 结果表明, 金属离子与EDTA的结合能(即配位稳定性)依次为: Cd^2＋＜Zn^2＋＜Co^2＋＜Ni^2＋＜Cu^2＋, 金属离子的水合吉布斯自由能计算值与实验值大致吻合, 而且上述目标金属配合物的络合吉布斯自由能的递变规律与实验一致. 基于气相优化结构进行了振动频率计算, 并对部分重要的振动峰作了归属指认. 结果表明, 随着配位稳定性的减弱, M(EDTA)^2－具有红外活性的金属敏感性振动峰ν(M—N)和ν(M—O)的峰位依次红移.     

Heterometallic SrII‐MII (M=Co,Ni, Zn and Cu) Coordination Polymers: Synthesis,Temperature‐Dependent Structural Transformation,and Luminescent and Magnetic Properties

The use of pyridine‐2,4‐dicarboxylic acid (H₂pydc) in the construction of Sr^II and Sr^II‐M^II (M=Co, Ni, Zn and Cu) coordination polymers is reported. Eight complexes, that is, [Sr(pydc)H₂O]_n ( 1 ), [MSr(pydc)₂(H₂O)₂]_n (M=Co ( 2 ), Ni ( 3 ), Zn ( 4 )), [ZnSr(pydc)₂(H₂O)₇]_n?4 nH₂O ( 5 ), [SrCu(pydc)₂]_n ( 6 ), [SrCu(pydc)₂(H₂O)₃]_n?2 nH₂O ( 7 ), and [Cu₃Sr₂(pydc)₄(Hpydc)₂(H₂O)₂]_n ( 8 ), have been synthesized via dexterously choosing the appropriate strontium sources and transition metal salts, and rationally controlling the temperature of the reaction systems. Complexes 1 , 2 ( 3 , 4 ), 6 , and 8 display four types of 3‐D framework structures. Complexes 5 and 7 exhibit a 2‐D network and a 1‐D chain structure, respectively. The 2‐D complex 7 can be reversibly transformed into 3‐D compound 6 through temperature‐induced solvent‐mediated structural transformation. The luminescent property studies indicated that complex 1 shows a strong purple luminescent emission and 4 exhibits a strong violet luminescence emission. The magnetic properties of 2 , 3 , and 8 were also studied. Antiferromagnetic M^II???M^II interactions were determined for these complexes.     

Jahn-Teller-Verzerrungen von Übergangsmetallionen in tetraedrischer Koordination – die Strukturen von Cat[MII(NCS)4] (MII: Co,Ni, Cu) und von Spinellmischkristallen MIICr2O4(MII: Zn?Ni,Zn?Cu,Cu?Ni)

Jahn-Teller Distortions of Transition Metal Ions in Tetrahedral Coordination — The Structures of Cat[M^II(NCS)₄]^II (M^II: Co, Ni, Cu) and of Mixed Crystals M^IICr₂O₄(M^II: Zn? Ni, Zn? Cu, Cu? Ni) of the Spinel Type The structure determination of compounds Cat[M^II(NCS)₄] with Cat = p-xylylenebis(triphenylphosphonium)²⁺ and M^II = Co, Ni, Cu [space group P2₁/n, Z = 4] yielded pseudotetrahedral M^IIN₄-polyhedra, which are distorted by packing forces and vibronic coupling effects of the Jahn-Teller type. Spinel mixed crystals with M^II = Zn? Ni, Zn? Cu, Ni? Cu in the tetrahedral sites exhibit phase transition to tetragonal and o-rhombic structures, induced by cooperative Jahn-Teller interactions. The distortion symmetries of the M^IIN₄ and M^IIO₄ tetrahedra are analysed on the basis of the respective electronic groundstate and the possible Jahn-Teller active vibrational modes.     

Molecule-based magnets formed by bimetallic three-dimensional oxalate networks and chiral tris(bipyridyl) complex cations. The series [ZII(bpy)3][ClO4][MIICrIII(ox)3] (ZII = Ru, Fe, Co, and Ni; MII = Mn, Fe, Co, Ni, Cu, and Zn; ox = oxalate dianion)

The synthesis, structure, and physical properties of the series of molecular magnets formulated as [ZII(bpy)3][ClO4][MIICrIII(ox)3] (ZII = Ru, Fe, Co, and Ni; MII = Mn, Fe, Co, Ni, Cu, and Zn; ox = oxalate dianion) are presented. All the compounds are isostructural to the [Ru(bpy)3][ClO4][MnCr(ox)3] member whose structure (cubic space group P4(1)32 with a = 15.506(2) A, Z = 4) consists of a three-dimensional bimetallic network formed by alternating MII and CrIII ions connected by oxalate anions. The identical chirality (lambda in the solved crystal) of all the metallic centers determines the 3D chiral structure adopted by these compounds. The anionic 3D sublattice leaves some holes where the chiral [Z(bpy)3]2+ and ClO4- counterions are located. These compounds behave as soft ferromagnets with ordering temperatures up to 6.6 K and coercive fields up to 8 mT.     

Synthesis and Characterization of New M‐Triazole Complexes (M = Co,Cu, Zn)

Three new complexes with the ligand 3,5‐diamino‐1,2,4‐triazole (Hdatrz), [Co₃(μ₂‐Hdatrz)₆(H₂O)₆]·(NO₃)₈·4H₂O ( 1 ), [Cu₃(μ₂‐Hdatrz)₄(μ₂‐Cl)₂(H₂O)₂Cl₂]·Cl₂·4H₂O·2C₂H₅OH ( 2 ) and {[Zn₂(μ₂‐SO₄) (μ₃‐datrz)₂]·2H₂O}_n ( 3 ) have been synthesized and structurally characterized. Complex 1 has a linear trinuclear mixed‐valence cobalt structure with six neutral triazole ligands in the N(1), N(2)‐bridging mode. The central cobalt atom, Co(1), is coordinated to six nitrogen atoms (octahedral) whereas the terminal cobalt atom, Co(2), is coordinated to an N₃O₃ moiety (octahedral). In complex 1 , the uudd cyclic water clusters, nitrate anions and the trimeric cations are linked to a supramolecular structure. Complex 2 features a linear trinuclear copper(II) core, with four N(1), N(2)‐bridging triazole ligands and two chlorido bridges. The central copper atom is coordinated to an N₄Cl₂ moiety (octahedral) whereas the terminal copper is coordinated to an N₂Cl₂O moiety (square‐pyramidal). In complex 2 , tetrahedral hydrogen bonding interactions play an important role to form a supramolecular network. Complex 3 exhibits a polymeric structure, with N(1), N(2), N(4)‐bridging triazolate ligands and sulfate bridges, in which zinc is coordinated to an N₃O moiety (tetrahedral). In complex 3 , water molecules and sulfate anions construct the sulfate‐water supramolecular chain with hydrogen bonding interactions. In addition, the complexes were investigated by elemental analyses, IR spectroscopic, and thermogravimetric measurements.