The Synthesis and Characterization of a New Cobalt Dimethylphenylpiperazinium Cyclotetraphosphate Hexahydrate,Co[C12 H19 N2]2 P4 O12.6 H2 O

Cobalt dimethylphenylpiperazinium cyclotetraphosphate hexahydrate, Co[C₁₂H₁₉N₂]₂P₄O₁₂.6H₂O, was synthesized by a reaction between cyclotetraphosphoric acid H₄P₄O₁₂, cobalt carbonate, and 1-(2,4-dimethylphenylpiperazine). It crystallizes in the triclinic system, space group P, with the following unit cell parameters: a = 7.336(1), b = 8.413(1), c = 14.926(2) Å, α = 87.46(1), β = 83.13(1), γ = 82.98(1)°, V = 907.3(2) ų, and Z = 1. The atomic arrangement can be described as layers containing P₄O₁₂ rings a and Co(H₂O)₆ octahedra spreading in the (001) planes between which are located the dimethylphenylpiperazinium groups via H-bonds. The synthesis and characterization by X-ray diffraction, IR absorption, and thermal analysis are described.     

Oxidation of linear trinuclear ruthenium complexes [Ru(3)(dpa)(4)Cl(2)] and [Ru(3)(dpa)(4)(CN)(2)]: synthesis, structures, electrochemical and magnetic properties

The neutral, monocationic, and dicationic linear trinuclear ruthenium compounds [Ru(3)(dpa)(4)(CN)(2)], [Ru(3)(dpa)(4)(CN)(2)][BF(4)], [Ru(3)(dpa)(4)Cl(2)][BF(4)], and [Ru(3)(dpa)(4)Cl(2)][BF(4)](2) (dpa=the anion of dipyridylamine) have been synthesized and characterized by various spectroscopic techniques. Cyclic voltammetric and spectroelectrochemical studies on the neutral and oxidized compounds are reported. These compounds undergo three successive metal-centered one-electron-transfer processes. X-ray structural studies reveal a symmetrical Ru(3) unit for these compounds. While the metal--metal bond lengths change only slightly, the metal--axial ligand lengths exhibit a significant decrease upon oxidation of the neutral complex. The electronic configuration of the Ru(3) unit changes as the axial chloride ligands are replaced by the stronger "pi-acid" cyanide axial ligands. Magnetic measurements and (1)H NMR spectra indicate that [Ru(3)(dpa)(4)Cl(2)] and [Ru(3)(dpa)(4)Cl(2)][BF(4)](2) are in a spin state of S=0 and [Ru(3)(dpa)(4)Cl(2)][BF(4)], [Ru(3)(dpa)(4)(CN)(2)], and [Ru(3)(dpa)(4)(CN)(2)][BF(4)] are in spin states of S=1/2, 1, and 3/2, respectively. These results are consistent with molecular orbital (MO) calculations.     

Synthesis,Crystal Structure,and Characterization of A New Adduct Bis-(2-Amino-3-Benzyloxypyridinium) Selenate Monohydrate [C12H13N2O]2SeO4.H2O

Abstract

A new adduct bis-(2-amino-3-benzyloxypyridinium) selenate monohydrate, [C₁₂H₁₃N₂O]₂SeO₄.H₂O, has been synthesized by slow evaporation at room temperature using 2-amino-3-benzyloxypyridine as the structure-directing agent. The structure, determined by single-crystal X-ray diffraction at 298 K, can be described as organic-inorganic tunnels with different forms built by infinite inorganic chains parallel to the c axis and connected to the organic cations. In this atomic arrangement, hydrogen bonds and van der Waals interactions between the different species play an important role in the tri-dimensional network cohesion. Solid-state ¹³C and ⁷⁷Se MAS NMR spectroscopy results are in agreement with the X-ray structure.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures and tables.]     

Gas-Phase Structures of Potassium Tetrakis(hexafluoro- acetylacetonato) Lanthanide(III) Complexes [KLn(C5HF6O2)4] (Ln=La,Gd, Lu)

The molecular structures of potassium tetrakis(hexafluoroacetylacetonato)lanthanide(III) complexes [KLn(hfa)₄] (Ln=La, Gd, Lu; hfa=C₅HF₆O₂,) were studied by synchronous gas-phase electron diffraction/mass spectrometry (GED/MS) supported by quantum-chemical (DFT/PBE0) calculations. The compounds sublime congruently and the vapors contain a single molecular species: the heterobinuclear complex [KLn(hfa)₄]. All molecules are of C₁ symmetry with the lanthanide atom in the center of an LnO₈ coordination polyhedron, while the potassium atom is coordinated by three ligands with formation of three K−O and three K−F bonds. One hfa ligand is not bonded to the potassium atom. Topological analysis of the electron-density distributions confirmed the existence of ionic-type K−O and K−F bonding. The structures of the free [KLn(hfa)₄] molecules are compared with those of the related compounds [KDy(hfa)₄] and [KEr(hfa)₄] in their crystalline state. The complex nature of the chemical bonding is discussed on the basis of electron-density topology analyses.     

Water exchange rates and mechanisms in tetrahedral [Be(H2O)4]2+ and [Li(H2O)4]+ complexes using DFT methods and cluster‐continuum models

The water exchange reactions in aquated Li⁺ and Be²⁺ ions were investigated with density functional theory calculations performed using the [Li(H₂O)₄]⁺·14H₂O and [Be(H₂O)₄]²⁺·8H₂O systems and a cluster‐continuum approach. A range of commonly used functionals predict water exchange rates several orders of magnitude lower than the experimental ones. This effect is attributed to the overstabilization of coordination number four by these functionals with respect to the five‐coordinated transition states responsible for the associative ( A ) or associative interchange ( I_a ) water exchange mechanisms. However, the M06 and M062X functionals provide results in good agreement with the experimental data: M062X/TZVP calculations yield a concerted I_a mechanism for the water exchange in [Be(H₂O)₄]²⁺·8H₂O that gives an average residence time of water molecules in the first coordination sphere of 260 μs. For [Li(H₂O)₄]⁺·14H₂O the water exchange reaction is predicted to follow an A mechanism with a residence time of inner‐sphere water molecules of 25 ps.     

Computation of aromatic C3N4 networks and synthesis of the molecular precursor N(C3N3)3Cl6

The successful synthesis and structural characterization of molecules that represent segments of extended solids is a valuable strategy for learning metric and stereochemical characteristics of those solids. This approach has been useful in cases in which the solids are particularly difficult to crystallize and thus their atomic connectivity and overall structures become difficult to deduce with X-ray diffraction techniques. One such class of materials is the covalently linked C(x)N(y) extended solids, where molecular analogues remain largely absent. In particular, structures of C(3)N(4) solids are controversial. This report illustrates the utility of a simple molecule, N(C(3)N(3))(3)Cl(6), in answering the question of whether triazine based C(3)N(4) phases are layered or instead they adopt 3D structures. Here, we present density functional calculations that clearly demonstrate the lower stability of graphitic C(3)N(4) relative to 3D analogues.     

三维超分子化合物[H_2(C_4H_(10)N_2)](SO_4)(H_2O)的制备、晶体结构及差热-热重性质研究

用MnSO4H2O和哌嗪在水-甲醇混合溶剂中反应得到了1个超分子化合物[H2(C4H10N2)](SO4)(H2O) (C4H14N2O5S)。 该晶体属单斜晶系, 空间群为P21/n, 晶胞参数为: a = 6.386(1), b = 11.695(2), c = 11.680(2) ? = 101.06(3), V = 856.1(3) 3, Z = 4, Mr =202.23 , Dc = 1.569 g/cm3, F(000) = 432, ?= 0.368 mm-1。 该化合物是由[H2(C4H10N2)]2+、SO42-、H2O通过氢键自组装而形成的。 其中[H2(C4H10N2)]2+存在2种椅式构象:一种[H2(C4H10N2)]2+与4个SO42-、2个H2O通过氢键相连, 另一种[H2(C4H10N2)]2+则与6个SO42-相连。 它们分别沿着b、c方向交替排列展开, 通过SO42-桥联成二维的层状结构;层与层之间在NH…O、CH…O、OH…O氢键的作用下互相连接, 形成了具有网状结构的三维超分子化合物。 差热及热重测试表明:该化合物从92℃开始分解,首先失去1个H2O, 然后再失去[H2(C4H10N2)]2+和SO4 2-。     

Li2 Trapped inside Tubiform [n] Boron Nitride Clusters (n=4–8): Structures and First Hyperpolarizability

The geometries and electronic properties of tubiform [n] boron nitride clusters entrapping Li₂ (Li₂@BN‐cluster(n,0); n=4–8), obtained by doping BN‐cluster(n,0) with Li₂ molecules, are investigated by means of DFT. The effects of tube diameter n on the dipole moment μ₀, static polarizability α₀, and first hyperpolarizability β₀ are elucidated. Both the dipole moment and polarizability increase with increasing tube diameter, whereas variation of the static first hyperpolarizability with tube diameter is not monotonic; β₀ follows the order 1612 (n=4)<3112 (n=5)<5534 (n=7)<8244 (n=6)<12 282 a.u. (n=8). In addition, the natural bond orbital (NBO) charges show that charge transfer takes place from the Li₂ molecule to the BN cluster, except for BN‐cluster(8,0) with larger tube diameter. Since the large‐diameter tubular BN‐cluster(8,0) can trap the excess electrons of the Li₂ molecule, Li₂@BN‐cluster(8,0) can be considered to be a novel electride compound.     

The Crystal Structures of Two No–Metal Tricyanomelaminates: Diammonium Tricyanomelaminate Dihydrate [NH4]2[C6N9H] · 2 H2O and Dimelaminium Tricyanomelaminate Melamine Dihydrate [C3N6H7]2[C6N9H] · C3N6H6 · 2 H2O

Diammonium tricyanomelaminate dihydrate [NH₄]₂[C₆N₉H] · 2 H₂O ( 1 ) and dimelaminium tricyanomelaminate melamine dihydrate [C₃N₆H₇]₂[C₆N₉H] · C₃N₆H₆ · 2 H₂O ( 2 ) were obtained by metathesis reactions from Na₃[C₆N₉] in aqueous solution and characterized by single‐crystal X‐ray diffraction and ¹⁵N solid‐state NMR spectroscopy ( 1 ). Both salts contain mono‐protonated tricyanomelaminate (TCM) anions and crystallize as dihydrates. Considering charge balance requirements, the crystal structure of 1 (C2/c, a = 3181.8(6) pm, b = 360.01(7) pm, c = 2190.4(4) pm, β = 112.39(3)°, V = 2319.9(8) 10⁶ · pm³) can best be described by assuming a random distribution of an ammonium ion – crystal water pair over two energetically similar sites. Apart from two melaminium cations, 2 (P2₁/c, a = 674.7(5) pm, b = 1123.6(5) pm, c = 3400.2(5) pm, β = 95.398(5), V = 2566(2) 10⁶ · pm³) contains one neutral melamine per formula unit acting as an additional “solvent” molecule and yielding a donor‐acceptor type of π–stacking interaction.