Indirect Nuclear <Superscript>77</Superscript>Se–<Superscript>77</Superscript>Se Spin–Spin Coupling Constants. Application of Density Functional Theory (DFT) Calculations

Calculations of the isotropic indirect nuclear spin–spin coupling constants ⁿJ(⁷⁷Se,⁷⁷Se) (n = 1,2,3) have been carried out at the B3LYP/6-311+G(d,p) level of theory. The compounds considered were non-cyclic and cyclic diselanes 1, boryl-substituted diselanes 2, dichlorodiselane 4, selenium Se₈, Se₆, Se₅ and various mixed selenium sulfides 3, and the bis(ethylene)tetraselenafulvalene (TSeF) 5. In comparison with experiment, both magnitude and sign, if available, were reproduced. The Coupled Perturbed DFT method gave the total coupling constant and the contributions arising from the Fermi contact term (FC), the spin-dipole (SD) and the spin.orbital terms (PSO and DSO). FC contributions play a minor role in most cases when compared with the non-contact terms.SD and PSO.     

Synthesis and Crystal Structure of Bis(tetraethylammonium) Octabromo‐triselenate(II)‐{dibromodiselenate(I)}, [NEt4]2[Se3Br8(Se2Br2)], the Salt of a Mixed‐valence Bromoselenate(II,I) Anion

The brown crystals of [NEt₄]₂[Se₃Br₈(Se₂Br₂)] ( 1 ) were obtained when selenium and bromine reacted in the solution of acetonitrile in the presence of tetraethylammonium bromide. The crystal structure of 1 has been determined by the X‐ray methods and refined to R = 0.0308 for 10433 reflections. The crystals are monoclinic, space group P2₁ with Z = 2 and a = 12.0393(3) Å, b = 11.8746(3) Å, c = 13.1946(3) Å, β = 96.561(1)° (123 K). In the solid state structure the anion of 1 is built up of Se₃Br₈ unit which consists of a triangular arrangement of three planar SeBr₄ units sharing a common edge through two μ₃‐bridging Br atoms, and one Se₂Br₂ molecule which is linked to one of μ₃‐bridging Br atoms. The three Se^II atoms form a triangle which is almost perpendicular to the planes given by three SeBr₄ moieties. The contact between the μ₃Br and the Se^I atom of the Se₂Br₂ molecule is 3.1711(8) Å and can be interpreted as a bond of the donor‐acceptor type with the μ₃Br as donor and the Se₂Br₂ molecule as acceptor. The terminal Se^II‐Br and μ₃Br‐Se^II bond lengths are in the ranges 2.3537(7)–2.4737(7) Å and 2.7628(7)–3.1701(7) Å, respectively. The bond lengths in coordinated Se₂Br₂ molecule are: Se^I‐Se^I = 2.2636(9) Å, Se^I‐Br = 2.3387(11) and 2.3936(8) Å.     

Two new 1-D lanthanide selenidogermanates with the [Ge2Se6]4− anion as a bridging ligand to a lanthanide complex cation

Two new 1-D lanthanide selenidogermanates [Ln₂(tepa)₂(μ-OH)₂(μ-Ge₂Se₆)]_n·xnH₂O (Ln = Tb (1), x = 0.5; Ln = Tm (2), x = 0; tepa = tetraethylenepentamine) have been solvothermally synthesized and structurally characterized. Compounds 1 and 2 contain 1-D polymeric chains [Ln₂(tepa)₂(μ-OH)₂(μ-Ge₂Se₆)]_n constructed by a [Ge₂Se₆]^4? anion as a bridging ligand with trans terminal Se atoms linking [Ln₂(μ-OH)₂(tepa)₂]⁴⁺ complex cations, but the stacking patterns of these neutral chains are different. The 1-D chains of 1 are alternately stacked in a crossing manner, while the infinite chains of 2 are arranged in a parallel manner. Although a few lanthanide selenidogermanates containing the [Ge₂Se₆]^4? anion have been reported, their [Ge₂Se₆]^4? anions are usually discrete. Compounds 1 and 2 provide the rare example of [Ge₂Se₆]^4? anion as a bridging ligand to a lanthanide complex cation. Their optical and magnetic properties have also been studied.     

Synthesis and Crystal Structure of Bis(methyltriethylammonium) Hexabromotellurate(IV)‐tris{dibromodiselenate(I)}, [NMeEt3]2n[TeBr6(Se2Br2)3]n,Containing a Chain‐Polymeric Mixed‐valence Bromotellurate(IV)‐Selenate(I) Anion

Red crystals of [NMeEt₃]_2n[TeBr₆(Se₂Br₂)₃]n ( 1 ) were isolated when selenium and bromine (1:1) were allowed to react in acetonitrile solution in the presence of tellurium(IV) bromide and methyltriethylammonium bromide (1:2). The salt 1 crystallizes in the monoclinic space group C2/c with the cell dimensions a = 27.676(6) Å, b = 9.665(2) Å, c = 18.796(4) Å and ß = 124.96(3)° (120 K). The [TeBr₆(Se₂Br₂)₃]^2— anions contain nearly regular octahedral [TeBr₆]^2— ions which are incorporated into a polymeric chain by bonding contacts between 3 facial bromo ligands and 3 Se₂Br₂ molecules, one of which is situated on the twofold symmetry axis. The distances between the μBr ligands and the Se^I atoms of the Se₂Br₂ molecules are observed in the range 3.308(2) — 3.408(2) Å and can tentatively be interpreted as donor‐acceptor bonds with μBr as donors and Se₂Br₂ as acceptors. The Te^IV—Br distances are in the range 2.669(1) — 2.687(1) Å. The bond lengths in the connecting Se₂Br₂ molecules are: Se^I—Se^I = 2.267(2) and 2.281(2) Å, Se^I—Br = 2.340(1), 2.353(1) and 2.337(1) Å.     

THE METASTABLE PARTIALLY POSITIVELY CHARGED Se6 MOLECULE: PREPARATION,CHARACTERISATION AND X-RAY CRYSTAL STRUCTURE OF [Ag2(Se6)(SO2)2][Sb(OTeF5)6]2, [Ag2Se6][AsF6]2 AND [AgSe6][Ag2(SbF6)3]

Reactions designed to give Se₆[Sb(OTeF₅)₆]₂ by the reaction of Se₂Br₂, 4Se, and 2Ag[Sb(OTeF₅)₆] lead to products that include [Ag₂(Se₆)(SO₂)₂][Sb(OTeF₅)₆]₂(1). The distorted cubic (Ag₂Se₆ ²⁺) _n consists of a Se₆ molecule bicapped by two silver cations (local D_3d sym.). Reactions of AgMX₆ (M = As, Sb) with selenium in liquid SO₂ yielded crystals of [Ag₂Se₆][AsF₆]₂ (2) and [AgSe₆][Ag₂(SbF₆)₃] (3). Both salts contain stacked arrays of [AgSe₆]⁺ half-sandwich cationic units. [Ag₂Se₆][AsF₆]₂ in addition contains stronger, linear Se─Ag─Se horizontal linkages between the vertically stacked cationic columns. [AgSe₆][Ag₂(SbF₆)₃] features a remarkable three-dimensional [Ag₂(SbF₆)₃]^? anion held together by strong Sb─F···Ag contacts between component Ag⁺ and SbF₆ ^? ions. Hexagonal channels through this honeycomb-like anion are filled by the stacked [AgSe₆ ⁺]_x.     

Synthesis and Crystal Structure of Bis(tetraphenylphosphonium) Hexabromo‐diselenate(II)‐bis{dibromodiselenate(I)}, [PPh4]2[Se2Br6(Se2Br2)2], the Salt of a Mixed‐valence Bromoselenate(II,I) Anion

The Red crystals of [PPh₄]₂[Se₂Br₆(Se₂Br₂)₂] ( 1 ) were obtained when selenium and bromine reacted in the solution of acetonitrile in the presence of tetraphenylphosphonium bromide. The crystal structure of 1 has been determined by X‐ray diffraction and refined to R = 0.0201 for 4024 reflections. The crystals are triclinic, space group with Z = 2 and a = 11.2757(4) Å, b = 12.3347(5) Å, c = 12.4948(5) Å, α = 113.152(4)°, β = 114.745(4)°, γ = 91.208(3)° (120(2) K). In the solid state the anion of 1 is built up of the Se₂Br₆ core and two Se₂Br₂ molecules each of which is linked to one of the trans‐positioned terminal Br_t atoms of the Se₂Br₆ core. The central Se₂Br₆ part consists of a nearly planar arrangement of two planar SeBr₄ units sharing a common edge through two μ₂‐bridging Br atoms. The contact between the Br_t and the Se^I atom of the Se₂Br₂ molecule is 3.0872(5) Å and can be interpreted as a bond of the donor‐acceptor type with the Br_t as donor and the Se₂Br₂ molecule as acceptor. The terminal Se^II–Br and μ₂Br–Se^II bond lengths are 2.3654(4), 2.6699(5) Å and 2.5482(5), 3.0265(5) Å, respectively. The bond lengths in the coordinated Se₂Br₂ molecule are: Se^I–Se^I = 2.2686(5) Å, Se^I–Br = 2.3779(5) and 2.3810(5) Å.     

Intermolecular Se···I Interactions Identified in Cu11(μ9‐Se)(μ3‐I)3[Se2P(OEt)2]6 Form a One Dimensional Polymeric Chain

The undecanuclear copper cluster Cu₁₁(μ9‐Se)(μ₃‐I)₃[Se₂P(OEt)₂]₆ 1 , has been isolated along with Cu₈(μ₈‐Se)[Se₂P(OEt)₂]₆ 2 , from the reaction of NH₄Se₂P(OEt)₂, Cu(CH₃CN)₄PF₆, and Bu₄NI in a molar ratio of 3:2:2 in diethyl ether. The molecular formulation of 1 was confirmed by elemental analysis, positive FAB mass spectrometry, multinuclear NMR (¹H, ³¹P, and ⁷⁷Se), and X‐ray diffraction. In cluster 1 eleven copper atoms adopt the geometry of a 3,3,4,4,4‐pentacapped trigonal prism with a selenium atom in the center. The coordination geometry for the central, nonacoordinated selenium atom is tricapped trigonal prismatic. In addition, the central core Cu₁₁Se is further stabilized by three iodides and six dsep ligands. Besides, weak inter‐molecular Se···I interactions (3.949–3.972 Å) are uncovered and form a one dimensional polymeric chain.     

Phosphor-1,1-Diselenolato Metal Complexes of Group 11 and 12

Abstract

Several copper and silver clusters containing diselenophosphate ligands such as tetranuclear [Cu{Se₂P(OR)₂}]₄, hexanuclear [Ag{Se₂P(OR)₂}]₆, octanuclear [Cu₈(μ₈-Se)}Se₂P(OR)₂}₆], [Ag₈(μ₈-Se)}Se₂P(OR)₂}₆], [Cu₈(μ₈-X)}Se₂P(OR)₂}₆](PF₆), [Ag₈(μ₈-X)}Se₂P(OR)₂}₆](PF₆), decanuclear [Ag₁₀(μ₁₀-Se)}Se₂P(OR)₂}₈], undecanuclear [Cu₁₁(μ₉-Se)(μ₃-X)₃}Se₂P(OR)₂}₆], [Ag₁₁(μ₉-Se)(μ₃-X)₃}Se₂P(OR)₂}₆], and dodecanuclear [Cu₁₂(P₂Se₆)}Se₂P(OR)₂}₈] have been isolated. All these clusters were well characterized in the solid-state and solution phase by elemental analysis, positive FAB mass spectrometry, multinuclear NMR (¹H, ³¹P, and ⁷⁷Se), and single crystal X-ray diffraction. In addition, tetranuclear zinc clusters [Zn₄(μ₄-Se){Se₂P(OPr)₂}₆], and [Zn₄(μ₄-O){Se₂P(OR)₂}₆] (R = Et, ⁱPr) also are synthesized and characterized. Solution studies of both [M{Se₂P(OEt)₂}₂]∞ and [M₂{Se₂P(OⁱPr)₂}₄] (M = Zn, Cd) which display a monomer-dimer equilibrium in solution were performed by VT ³¹P NMR in CD₂Cl₂.     

Syntheses,crystal structures,and electrochemical studies of diiron complexes from the reactions of [Et3NH][(μ-RS) Fe2(CO)6(μ-CO)] with isothiocyanates

Reactions of [Et₃NH][(μ-MeO₂CCH₂S)Fe₂(CO)₆(μ-CO)] in situ generated from the mixture of MeO₂CCH₂SH, Et₃N, and Fe₃(CO)₁₂ with 2-C₅H₄NNCS, 3-C₅H₄NNCS, and EtNCS in THF, form 1, (μ-MeO₂CCH₂S)Fe₂(CO)₅(μ-k²N,S:k²C-2-C₅H₄NNHCS), 2, (μ-MeO₂CCH₂S)Fe₂(CO)₆(μ-k²C,S-3-C₅H₄NNHCS), and 3, (μ-MeO₂CCH₂S)Fe₂(CO)₆(μ-k²C,S-EtNHCS). Reaction of [Et₃NH][(μ-PhS)Fe₂(CO)₆(μ-CO)] in situ formed from the mixture of PhSH, Et₃N, and Fe₃(CO)₁₂ with EtNCS affords 4, (μ-PhS)Fe₂(CO)₆(μ-k²C,S-EtNHCS). Reaction of [Et₃NH][(μ-EtS)Fe₂(CO)₆(μ-CO)] in situ produced from the mixture of EtSH, Et₃N, and Fe₃(CO)₁₂ with EtNCS offers 5, (μ-EtS)Fe₂(CO)₆(μ-k²C,S-EtNHCS). All new complexes have been fully characterized by EA, IR, ¹H NMR, and ¹³C NMR and structurally determined by X-ray crystallography. Electrochemical studies on 2 and 5 confirm that 2 shows high H₂-producing activity.     

Reaction of Selenium with Bromine in the Presence of Methyltriphenylphosphonium Bromide: Syntheses and Crystal Structures of [PMePh3]2[Se2Br6] and [PMePh3]2[SeBr6(SeBr2)2]

The brown crystals of [PMePh₃]₂[Se₂Br₆] ( 1 ) and red crystals of [PMePh₃]₂[SeBr₆(SeBr₂)₂] ( 2 ) were obtained when selenium and bromine reacted in the solution of acetonitrile in the presence of methyltriphenylphosphonium bromide. The crystal structures of 1 and 2 has been determined by the X‐ray methods and refined to R = 0.0373 for 2397 reflections and 0.0397 for 3417 reflections, respectively. The salt 1 crystallizes in the monoclinic space group P2₁/n with the cell dimensions a = 13.202(5) Å, b = 11.954(4) Å, c = 13.418(6) Å, β = 93.08(4)° (193(2)). The crystals of 2 are triclinic, space group with the cell dimensions a = 10.266(3) Å, b = 11.311(3) Å, c = 11.619(2) Å, α = 108.87(2)°, β = 105.72(2)°, γ = 99.40(2)° (193(2) K). In the solid state structure of 1 the dinuclear hexabromo‐diselenate(II) anion is centrosymmetric and consists of two distorted almost square planar SeBr₄ units sharing a common edge through two μ‐bridging Br atoms. The terminal Se^II–Br bonds are 2.3984(11) and 2.4273(11) Å, whereas the bridging μBr–Se^II bonds are 2.7817(11) and 2.9081(12) Å. In the solid state the trinuclear [SeBr₆(SeBr₂)₂]^2? anion of 2 is centrosymmetric too and contains a nearly regular [SeBr₆] octahedron where the four equatorial bromo ligands each have developed bonds to the Se^II atoms of the SeBr₂ molecules. The contacts between the bridging bromo and the Se^II atoms of the SeBr₂ molecules are 3.0603(15) and 3.1043(12) Å, and can be interpreted as bonds of the donor‐acceptor type with the bridging bromo ligands as donors and the SeBr₂ molecules as acceptors. The Se^IV–Br distances are in the range 2.5570(9)–2.5773(11) Å and the Se^II–Br bond lengths in coordinated SeBr₂ molecules – 2.3411(12) and 2.3421(10) Å.     

Direct Syntheses of Bis(tetraphenylphosphonium) and Bis(ethyltriphenylphosphonium) Hexabromo‐diselenates(II), [PPh4]2[Se2Br6] and [PEtPh3]2[Se2Br6]. The Crystal Structure of [PEtPh3]2[Se2Br6]

Brown crystals of [PPh₄]₂[Se₂Br₆] ( 1 ) and [PEtPh₃]₂[Se₂Br₆] ( 2 ) were obtained when selenium and bromine reacted in acetonitrile solution in the presence of tetraphenylphosphonium bromide and ethyltriphenylphosphonium bromide, respectively. The crystal structure of 2 has been determined by X‐ray methods and refined to R = 0.0420 for 4161 reflections. The crystals are monoclinic, space group P2₁/n with Z = 2 and a = 13.055(3) Å, b = 12.628(3) Å, c = 13.530(3) Å, β = 92.40(3)° (293(2) K). In the solid state structure of 2 the dinuclear hexabromo‐diselenate(II) anion is centrosymmetric and consists of two distorted almost square‐planar SeBr₄ units sharing a common edge through two bridging Br atoms. The terminal Se^II–Br bond distances are found to be 2.419(1) and 2.445(1) Å, the bridging μBr–Se^II bond distances 2.901(1) and 2.802(1) Å.     

Neue Kronenether‐stabilisierte Oxoniumhalogenochalkogenate: [H3O(Dibromo‐benzo‐18‐Krone‐6)]2[Se3Br10] und [H5O2(Bis‐dibromo‐dibenzo‐24‐Krone‐8]2[Se3Br8]

Novel Oxonium Halogenochalcogenates Stabilized by Crown Ethers: [H₃O(Dibromo‐benzo‐18‐crown‐6)]₂[Se₃Br₁₀] and [H₅O₂(Bis‐dibromo‐dibenzo‐24‐crown‐8]₂[Se₃Br₈] Two novel complex oxonium bromoselenates(II,IV) and –(II) are reported containing [H₃O]⁺ and [H₅O₂]⁺ cations coordinated by crown ether ligands. [H₃O(dibromo‐benzo‐18‐crown‐6)]₂[Se₃Br₁₀] ( 1 ) and [H₅O₂(bis‐dibromo‐dibenzo‐24‐crown‐8]₂[Se₃Br₈] ( 2 ) were prepared as dark red crystals from dichloromethane or acetonitrile solutions of selenium tetrabromide, the corresponding unsubstituted crown ethers, and aqueous hydrogen bromide. The products were characterized by their crystal structures and by vibrational spectra. 1 is triclinic, space group (Nr. 2) with a = 8.609(2) Å, b = 13.391(3) Å, c = 13.928(3) Å, α = 64.60(2)°, β = 76.18(2)°, γ = 87.78(2)°, V = 1404.7(5) ų, Z = 1. 2 is also triclinic, space group with a = 10.499(2) Å, b = 13.033(3) Å, c = 14.756(3) Å, α = 113.77(3)°, β = 98.17(3)°, γ = 93.55(3)°. V = 1813.2(7) ų, Z = 1. In the reaction mixture complex redox reactions take place, resulting in (partial) reduction of selenium and bromination of the crown ether molecules. In 1 the centrosymmetric trinuclear [Se₃Br₁₀]^2? consists of a central Se^IVBr₆ octahedron sharing trans edges with two square planar Se^IIBr₄ groups. The novel [Se₃Br₈]^2? in 2 is composed of three planar trans‐edge sharing Se^IIBr₄ squares in a linear arrangement. The internal structure of the oxonium‐crown ether complexes is largely determined by the steric restrictions imposed by the aromatic rings in the crown ether molecules, as compared to complexes with more flexible unsubstituted crown ether ligands.     

Synthesis and characterization of 2-hydroxy-pyridine modified Group 4 alkoxides

The reaction of Group 4 metal alkoxides ([M(OR)₄]) with the potentially bidentate ligand, 2-hydroxy-pyridine (2-HO-(NC₅H₄) or H-PyO), led to the isolation of a family of compounds. The products isolated from the reaction of [M(OR)₄] [where M = Ti, Zr, or Hf; OR = OPrⁱ (OCH(CH₃)₂), OBu^t (OC(CH₃)₃), or ONep (OCH₂C(CH₃)₃] under a variety of stoichiometries with H-PyO were identified by single crystal X-ray diffraction as [(OPrⁱ)₂(PyO-κ²(O,N))Ti(μ-OPrⁱ)]₂ (1), [(ONep)₂Ti(μ(O)-PyO-κ²(O,N))₂(μ-ONep)Ti(ONep)₃] (2), [(ONep)₂Ti(μ(O)-PyO-κ²(O,N))(η¹(N),μ(O)-PyO)(μ-O)Ti(ONep)₂]₂ (2a), [H][(PyO-κ²(O,N))(η¹(O)-PyO)Ti(ONep)₃] (3), [(OR)₂Zr(μ(O)-PyO-κ²(O,N))₂(μ-OR)Zr(OR)₃] (OR = OBu^t (4), ONep (5)), [(OR)₂Zr(μ(O,N)-PyO-κ²(O,N))₂(μ(O,N)-PyO)Zr(OR)₃] (OR = OBu^t (6), ONep (7)), [[(OBu^t)₂Zr(μ(O)-PyO-(κ²(N,O))(μ(O,N)-PyO)₂Zr(OBu^t)](μ₃-O)]₂ (6a), [[(ONep)(PyO-κ²(N,O))Zr(μ(O,N)-PyO-κ²(N,O))₂(μ(O)-PyO-κ²(N,O))Zr(ONep)](μ₃-O)]₂ (7a), [(OBu^t)(PyO-κ²(O,N))Zr(μ(O)-PyO-κ²(O,N))₂((μ(O,N)-PyO)Zr(OBu^t)₃] (8), [(OBu^t)₂Hf(μ(O)-PyO-κ²(N,O))₂(μ-OBu^t)Hf(OBu^t)₃] (9), [(OR)₂ M(μ(O)-PyO-κ²(N,O))₂(μ(O,N)-PyO)M(OR)₃] (OR = OBu^t (10), ONep (11)), and [(ONep)₃Hf(μ-ONep)(η¹(N),μ(O)-PyO)]₂Hf(ONep)₂ (12)·tol. The structural diversity of the binding modes of the PyO led to a number of novel structure types in comparison to other pyridine alkoxy derivatives. The majority of compounds adopt a dinuclear arrangement (1, 2, 4–11) but oxo-based tetra- (2a and 7a), tri- (12), and monomers (3) were observed as well. Compounds 1–12 were further characterized using a variety of analytical techniques including Fourier Transform Infrared Spectroscopy, elemental analysis, and multinuclear NMR spectroscopy.     

Three Cu(II) (R)-2-chloromandelato complexes generated from dipyridyl-type ligands with different spacer lengths: syntheses,crystal structures,and ferroelectric properties

Three Cu(II) complexes, Cu₂(bpy)(H₂O)(Clma)₂ (1), Cu₂(bpe)(H₂O)₂(Clma)₂ (2), and Cu(bpp)(Clma) (3), were synthesized (HClma = (R)-2-Chloromandelic acid, bpy?=?4,4′-dipyridine, bpe?=?1,2-di(4-pyridyl)ethylene, bpp?=?1,3-di(4-pyridyl)propane). Complexes 1, 2, and 3 are constructed from 1-D coordination arrays generated from Cu₂(H₂O)(Clma)₂, Cu₂(H₂O)₂(Clma)₂, and Cu₂(Clma)₂ moieties and linked through bpy, bpe, and bpp co-ligands, respectively. 1 and 2 are assembled into 3-D supramolecular networks via O–H?O hydrogen bonds with topology of (6³)(6⁹·8) and (4¹²·6³), respectively, and 3 is assembled into a 3-D architecture through C–H?O hydrogen bonds with topology of (4³·6³)(4³)(4⁴·6⁵·8)(4⁶·6⁶·8³). Compounds 1, 2, and 3 crystallized in acentric space groups P2₁, P1, and P2₁, which exhibit significant ferroelectricity (remnant polarization Pr?=?0.008?μC?cm^?2, coercive field Ec?=?21.4?kV?cm^?1, the spontaneous saturation polarization Ps?=?0.167?μC?cm^?2 for 1, Pr?=?0.183?μC?cm^?2, Ec?=?1.69?kV?cm^?1, and Ps?=?0.021 μC?cm^?2 for 3). Results from infrared and thermal analyses are also discussed.     

Organic–Inorganic Hybrid Material Based on Strandberg-Type Polyanion [Se2Mo5O21]4− and 2-Aminopyridine Ions

A new organic–inorganic hybrid compound (2-AMP)₄[Se₂Mo₅O₂₁]·2H₂O (1) [2-AMP = 2-aminopyridinium] has been synthesized and characterized by IR spectrum, UV–Vis spectra, ¹H NMR spectroscopy, thermogravimetric analyses, cyclic voltammetry measurements and single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic system with space group P-1 and a = 11.451(6) Å, b = 13.478(3) Å, c = 14.037(2) Å, α = 108.956(2)°, β = 96.260(2)°, γ = 97.174(3)°, Z = 2. The title compound contains four protonized 2-AMP cations, five distorted MoO6 octahedra and two SeO3 pyramids by sharing vertices and edges. These five Mo atoms are nearly coplanar, and two SeO3 pyramids lie on both sides of this plane. The interactions between [Se₂Mo₅O₂₁]^4? clusters are established through hydrogen contacts which involve selenium, water molecules and 2-aminopyridine cations to form a three-dimensional structure.     

Novel Three-Dimensional Coordination Polymers Based on [Mo6Se8(CN)6]7− Anions and Mn2+ Cations

Three novel coordination polymers K₅[MnMo₆Se₈(CN)₆] · 8H₂O (1), (Me₄N)₄[{Mn(H₂O)₂}_1.5Mo₆Se₈(CN)₆] · 4H₂O (2), and K₃[{Mn₂(H₂O)₄}Mo₆Se₈(CN)₆] · 7H₂O (3) have been synthesized by layering of a methanol solution of [Mn(salen)]CH₃COO (salen–N,N′-bis(salicylidene)ethylenediamine) on an aqueous solution of K₇[Mo₆Se₈(CN)₆] · 8H₂O. The compounds have been characterized by single-crystal X-ray diffraction analysis. All structures are based on negatively charged porous polymer frameworks where CN groups of [Mo₆Se₈(CN)₆]⁷⁻ cluster complexes are coordinated to Mn²⁺ cations. Cavities in the frameworks are filled by additional cations and solvate water molecules.     

Fluorocarbon-selenium chemistry: Accomplishments and quests

The binary selenium fluorides SeF_n (n = 2, 4, 6) and Se₂F₂ are considered along with corresponding perfluorohalogenoorgano- selenium compounds with selenium in the oxydation states 1, 2, 4 and 6. For lower selenium fluorides, preparation and characterisation are emphasized. Recent results in the chemistry of SeCF₂, CF₃SeCl, CF₃SeSeCF₃, CF₃Se(O)OM and CF₃Se^VI- compounds are presented. A comparison with the corresponding sulfur chemistry is also provided.     

Synthesis and characterization of linked alkyne-bridging Co2C2 tetrahedral clusters and expansion reactions of (Co2(CO)6(μ-HCCCH2OOC))2R with Fe3(CO)12

Two new linked alkyne-bridging tetrahedral carbonyl clusters containing Co₂C₂ Co₂(CO)₆(μ-HCCCH₂OOC(CH₂)₃COOCH₂CCH-μ)Co₂(CO)₆, 1, and Co₂(CO)₆(μ-HCCCH₂OOC(CH₂)₈COOCH₂CCH-μ)Co₂(CO)₆, 2, have been prepared by reactions of two dipropargyl esters (HC≡CCH₂OOC)₂R (R = (CH₂)₃, (CH₂)₈) with Co₂(CO)₈. Expansion reactions of 1 and Co₂(CO)₆(μ-HCCCH₂OOCCOOCH₂CCH-μ)Co₂(CO)₆, 3, with Fe₃(CO)₁₂ give two new mixed-metal linked clusters Co₂(CO)₆(μ-HCCCH₂OOC(CH₂)₃COOCH₂CCH-μ,η⁴)Co₂Fe₂(CO)₁₂, 4, and Co₂(CO)₆(μ-HCCCH₂OOCCOOCH₂CCH-μ,η⁴)Co₂Fe₂(CO)₁₂, 5. The new clusters were characterized by elemental analysis, IR, ¹H-NMR and ESI-MS analysis.     

Kalium-μ-dithio-bis(pentacyanokobaltat(III)) und Kalium-μ-diseleno-bis(pentacyanokobaltat(III))

Potassium-μ-dithio-bis(pentacyanocobaltate(III)) and Potassium-μ-diseleno-bis(pentacyanocobaltate(III)) The oxidation of [Co(CN)₅]^3? by sulfur or selenium leads to the complexes [Co₂S₂(CN)₁₀]^6? and [Co₂Se₂(CN)₁₀]^6?, respectively, which have been isolated as potassium salts K₆[Co₂S₂(CN)₁₀] · 4 H₂O and K₆[Co₂Se₂(CN)₁₀] · 5 H₂O. The μ-dithio complex has also been formed from [Co(CN)₅]^3? with polysulfide, from [CoOH(CN)₅]^3? with H₂S + O₂ and from [Co₂O₂(CN)₁₀]^6? with H₂S. As shown by their vibrational spectra the new complexes contain bridges Co? S? S? Co and Co? Se? Se? Co, respectively.