Crystal and molecular structure of the photocatalyst tris(2,2′-bipyrazine)ruthenium(II) hexafluorophosphate

The X-ray structure determination of the complex tris(2,2-bipyrazine)ruthenium(II) hexafluorophosphate, [Ru(C₈N₄H₆)₃](PF₆)₂, has shown that the compound crystallizes in the monoclinic space group P2₁/c witha=13.459(5),b=23.486(8),c=17.913(10) Å,=139.85(1)°, andZ=4. Each asymmetric unit also contains one dimethylformamide and one water molecule. Least-squares refinement led to an R factor of 0.074 based on 3463 reflections for which I>2(I). The [Ru(C₈N₄H₆)₃]²⁺ cation has no crystallographic symmetry, but the requirements for point symmetry 32 are nearly met. The six Ru-N bond lengths agree within experimental error and have an average length of 2.05(1) Å.     

X-ray diffraction structure of the phosphido-bridged mixed-metal cluster Fe2(CO)6(μ3-PPh)2Pt(dppe)

Treatment of Fe₂(CO)₆(₂-PPhH)₂ with BuLi (2 equiv.), followed by the addition of PtCl₂ (dppe), affords the phosphido-bridged cluster Fe₂(CO)₆(₃-PPh)₂Pt(dppe). The Fe₂Pt cluster was isolated and characterized in solution by IR and ³¹P NMR spectroscopy, and the molecular structure of Fe₂(CO)₆(₃-PPh)₂Pt(dppe) determined by X-ray diffraction analysis. Fe₂(CO)₆(₃-PPh)₂Pt(dppe) crystallizes in the orthorhombic space group P_bca, a = 17.539(3) Å, b = 21.490(2) Å, c = 22.959(3) Å, V = 8653.5(18) ų, Z = 8, d_calc = 1.670 g cm^–3; R = 0.0644, R_w = 0.0389 for 5040 observed reflections with I > 3(I).     

Complexes in the Ni2+-imidazole-RN(CH2COO−)2 systems. The crystal structures of tris(imidazole)iminodiacetatonickel(II) monohydrate, hexa(imidazole)nickel(II) bis(N-methyliminodiacetato)nickelate(II) hexahydrate, and tetra(aqua)bis(imidazole)nickel(II) bis(N-benzyliminodiacetato)nickelate(II)

Crystals of different compositions, namely, [Ni(Ida)(Im)₃] ? H₂O (I), [Ni(Im)₆][Ni(Mida)₂] ? 6H₂O (II), and [Ni(Im)₂(H₂O)₄][Ni(Bida)₂] (III), have been precipitated from aqueous solutions of the Ni²⁺-Lig ^2?-Im systems, where Lig ^2? is Ida, Mida, and Bida, respectively. The crystal structures of I–III are determined by X-ray diffraction analysis (R = 0.0307, 0.0348, and 0.0302 for 3061, 4706, and 2882 reflections, respectively). Crystals I are built of monomeric mixed-ligand complexes and molecules of crystallization water, which are interlinked by hydrogen bonds into a three-dimensional framework. In II and III, the ligands Lig ^2? and Im form charged complexes separately. In II, the cationic and anionic layers of the complexes alternate along the c-axis. Numerous hydrogen bonds involving molecules of crystallization water link the layers into a three-dimensional framework. In III, the cationic and anionic complexes, which serve as proton donors and acceptors, respectively, are bound into layers parallel to the xy plane.     

Nickel(II) and palladium(II) complexes of dithiomalonamides: Ligands which favor the formation of π-conjugation systems in the coordination

The spectra (IR and NMR) of the nickel(II) and palladium(II) complexes of dithiomalonamide (Hdtma) andN,N-diphenyldithiomalonamide (Hdpdtma) are discussed in the light of the structure of the bis(N,N-diphenyldithiomalonamidato) nickel(II) di(N,N-dimethylformamide)solvate. The compound crystallizes in the triclinic space groupP¯1 (No. 2) witha=11.113(2),b=10.173(2),c=9.912(1) Å,a=74.47(6),=108.83(7),=114.10(7)°,Z=1 (R=0.0495 andR _w =0.052). The crystals consist of discrete [Ni(dpdtma)₂] andN,N-dimethylformamide (DMF) molecules. The nickel atom is chelated by two centrosymmetrically related ligands via sulfur atoms in an approximately squareplanar arrangement. The ligand moiety in the nickel coordination forms a-conjugation system. The DMF solvate molecules are involved in hydrogen bonding with the NH groups of the ligand. The best fit of the IR band assignments was obtained by comparing the spectra of the complexes with those of     

X-ray diffraction structure of the 1,1′-bis(diphenylphosphino)ferrocene (dppf)-bridged complex [(dppf)AgCl]2: An unexpected product from the reaction betweencis-(bpy)2RuCl2 and dppf in the presence of AgBF4

The reaction betweencis-Ru(bpy)₂Cl₂ (where bpy=bipyridine) and the diphosphine ligand 1,1-bis(diphenylphosphino)ferrocene (dppf) in the presence of AgBF₄ has led to the isolation of the title compound [Ag(dppf)Cl]₂. [Ag(dppf)Cl]₂ has been structurally characterized by X-ray diffraction analysis, which confirms the bridging mode adopted by the ancillary dppf ligand and the centrosymmetric nature of this molecule. Dimeric [Ag(dppf)Cl]₂ crystallizes in the triclinic space group ,a=11.426(1) Å,b=11.509(1) Å,c=12.786(1) Å, =68.96(2)°, =70.66(2)°, =71.24(2)°,V=1441(1) ų,Z=1,d _calc=1.608 g·cm^–3;R=0.0445,R _w=0.0566 for 4486 observed reflections withl>3(l)     

Reaction of the dicobalt alkyne compound Co2(CO)6(μ-dmad) with the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). Spectroscopic properties, X-ray diffraction data, and thermal reactivity of the chelating isomer of Co2(CO)4(bpcd)(μ-dmad)

Treatment of Co₂(CO)₆(-dmad) (where dmad = dimethyl acetylenedicarboxylate) with the bidentate ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) in the presence of added Me₃NO affords the new alkyne compound Co₂(CO)₄(bpcd)(-dmad) in good yield. Both IR and ³¹P NMR spectroscopies indicate that the bpcd ligand is coordinated to a single cobalt center in a chelating fashion in solution. The solid-state structure of Co₂(CO)₄(bpcd)(-dmad) is identical to the solution structure Co₂(CO)₄(bpcd)(-dmad), as determined by X-ray diffraction analysis. Co₂(CO)₄(bpcd)(-dmad) crystallizes in the triclinic space group P-1, a = 10.7460(8) Å, b = 11.628(2) Å, c = 15.077(1) Å, = 95.831(9)°, = 91.205(7)°, = 101.526(9)°, V = 1834.7(3) ų, Z = 2, and d _calc = 1.514 g/cm³; R = 0.0489, R _w = 0.0528 for 2854 reflections with I > 3(I). The thermal reactivity of Co₂(CO)₄(bpcd)(-dmad) has been briefly explored by spectroscopic methods, and evidence is presented for the attack of one of the PPh₂ groups on an alkyne carbon atom in Co₂(CO)₄(bpcd)(-dmad) to from the zwitterionic hydrocarbyl compound Co₂(CO)₄(-²:²:¹:¹-(MeO₂C)=C(CO₂Me)PPh₂C=C(PPh₂)C(O)CH₂C(O)] upon thermolysis. The redox chemistry of both Co₂(CO)₄(bpcd)(-dmad) and Co₂(CO)₄[-²:²:¹:¹-(MeO₂C) C=C(CO₂Me)PPh₂C=C(PPh₂)C(O)CH₂C(O)] has been explored by cyclic voltammetery.     

Reaction of 1,2-bis(diphenylphosphino)cyclobutenedione (bpcbd) with fac-BrRe(CO)3(THF)2: X-ray diffraction structure of the dimeric complex [BrRe(CO)3]2(bpcbd) ⋅ CH2Cl2

Treatment of the diphosphine ligand 1,2-bis(diphenylphosphino)cyclobutenedione (bpcbd) with the THF adduct fac-BrRe(CO)₃(THF)₂ at room temperature furnishes the new dirhenium compound [BrRe(CO)₃]₂(bpcbd) instead of the expected mononuclear compound fac-BrRe(CO)₃(bpcbd). [BrRe(CO)₃]₂(bpcbd) was characterized in solution by IR spectroscopy, and the solid-state structure was solved by X-ray crystallography. [BrRe(CO)₃]₂(bpcbd), as the CH₂Cl₂ solvate, crystallizes in the space group P , a = 11.173(1), b = 13.362(1), c = 15.250(1) Å, = 108.973(7)°, = 99.477(8)°, = 110.466(7)°, V = 1915.0(3) ų, Z = 2, and d _calc = 2.143 g-cm^–3. The structure of [BrRe(CO)₃]₂(bpcbd) consists of two rhenium centers that are six-coordinate and possess nearly ideal octahedral geometry. The two Re(CO)₃ units are linked together by the bridging diphosphine ligand and two bridging bromide groups.     

Investigation of the structure and properties of (K x (NH4)1 − x )3H(SO4)2 single crystals

The influence of isomorphous replacement in the cation sublattice on the kinetics of the phase transition in single crystals of the solid solutions (K _x (NH₄)_{1 ? x} ) _m H _n (SO₄)_{(m + n)/2} · yH₂O belonging to the K₃H(SO₄)₂-(NH₄)₃H(SO₄)₂-H₂O salt system was studied. Superproton phase transitions for the end compositions of this system have been found earlier. The optical and thermal properties of crystals with the composition (K,NH₄)₃H(SO₄)₂ in the temperature range from 295 to 500 K were investigated, and the crystal structure was determined at 295 K. The results of the study and the comparison with the literature data show that the replacement of potassium atoms with ammonia leads to a fundamental change in the kinetics of the phase transition, the phase-transition temperature remaining virtually unchanged.     

A Spin-Charge Separation Hypothesis Based on the Structure of the Salts (TMTSF)2 × (X=PF− 6, ASF− 6)

A detailed study of the three-dimensional structure of (TMTSF)₂AsF₆ isomorphous to the PF₆ and ClO₄ salts) has led to the conclusion that these salts are pseudo two-dimensional, that there are strong interactions between certain selenium atoms in specific ways (clustering) and that there is a periodic lattice of anions. These anion sheets could stabilize partial separation of positive charges and unpaired electrons (spins). This separation can be used to formulate an hypothesis to explain the apparent absence of CDW's in these salts.     

Peculiarities of the Electron Structure of Pseudobinary Alloys (GeTe)m–(Sb2Te3)n

Crystallography Reports - The electron band structure of GeTe, Sb2Te3, GeSb2Te4, and Ge2Sb2Te5 compounds has been calculated by the electron density functional method using the WIEN2k software...     

Structure of the α-(allcis) form of 2,4,6-tris(trichloromethyl)-1-oxa-3,5-dithian

The higher-melting (mp 236°C)-isomer of dithioparachloral, i.e.,-2,4,6-tris(trichloromethyl)-1-oxa-3,5-dithian, is orthorhombic,Pnma,a=9.983(2),b=15.318(2),c=10.416(2) Å,V=1592.81 ų,Z=4. The structure was solved by direct methods, from data collected at room temperature on an Enraf-Nonius CAD4 diffractometer, and refined by least-squares to a finalR value of 0.040 using 1017 reflections. The molecule is in the chair conformation with all threecis-CCl₃ groups located pseudoequatorially. Endocyclic parameters are: torsion angles (deg) C-O-C-S 75.1(3), O-C-S-C –63.2(3), C-S-C-S 62.4(3); angles (deg) C-O-C 111.9(2), O-C-S 112.6(3), C-S-C 94.8(2), S-C-S 113.2(1); bond lengths (Å) O-C 1.426(5), C-S 1.824(4), S-C 1.818(3) (quoted in cyclic order).     

Crystal structure and spectroscopy of the high-spin compound: Tris-(2,2′-bipyridine-1,1′-dioxide)Iron(III) tris(perchlorate) bis(acetonitrile), [Fe(bpdo)3](ClO4)3(CH3CN)2

The first high-spin iron(III) compound with the ligand 2,2-bipyridine-1,1-dioxide (abbreviated as bpdo) is reported. The compound [Fe(bpdo)₃](ClO₄)₃(CH₃CN)₂ crystallizes in the space group P , with a = 11.767(3), b = 13.166(4), c = 15.951(4) Å, = 104.62(3), = 101.66(3), = 112.14(3)°, and Z = 2. The Fe(III) atom is octahedrally surrounded by six oxygen atoms of three bpdo ligands. In the far-infrared region the Fe—O vibration is observed at 411 cm^–1. The magnetic susceptibility reveals a of 6.04 ± 0.04 BM in the 10–280 K region, typical of high-spin Fe(III).     

On the kinetics of the decomposition of ternary Al-Zn(6at.%)?Mg(X) and Al?Mg(X)?Si(Y) alloys

Investigations on Al-Zn(3)-Mg(X) alloys gave the rather surprising result that the migration energies depend on the physical quantities (resistivity, Young's modulus) and the ageing time used. Therefore it is the aim of this paper to test, if similar effects occur using other ternary alloys and additional measuring methods. The ageing kinetics of 7 Al-Zn(6)-Mg(X) alloys are examined by isothermal measurements of resistivity, Young's modulus, change of length, and microhardness over a relatively long time interval of about 3 h within the temperature range from 20°C to 90°C.

• 1 The activation energies got for the Al-ZN(6)-Mg(X) alloys depend on the physical quantity as well as on the ageing time used within the temperature range from 20°C to 40°C as known from the Al-Zn(3)-Mg(X) alloys.
• 2 The activation energies obtained for the Al-Zn(6)-Mg(1.3) alloy in the temperature interval from 50°C to 90°C decrease monotonously with increasing time for the measuring methods considered.

These results different with respect to those two temperatur ranges are probably caused by a change of the decomposition mechanism. Below 40°C presumably several kinds of clusters are formed in the beginning of the decomposition, but above 50°C probably only one sort of clusters should grow. The late stage of ageing should be caused mainly by the diffusion of VZn₂ complexes (E^M = 0.21 eV) in the temperature range investigated, since 0.2 eV holds for that stage. – Finally the results of the investigations of the kinetics of some Al-Mg(X)-Si(Y) alloys are discussed by means of the jump model.     

Synthesis, redox chemistry, and X-ray structure of the mixed-metal cluster Fe2(CO)6(μ3-S)2Ni(dppf)

The reaction between the dianion [Fe₂(CO)₆(₂-S)₂]^2– and NiCl₂(dppf) occurs readily at room temperature to give the mixed-metal cluster Fe₂(CO)₆(₃-S)₂Ni(dppf) in moderate yield. Fe₂(CO)₆(₃-S)₂Ni(dppf) was isolated by preparative chromatography and its solid-state structure established by X-ray diffraction analysis. Fe₂(CO)₆(₃-S)₂Ni(dppf) crystallizes in the monoclinic space group C2/c, a = 20.320(6), b = 13.114(2), c = 15.622(2) Å, = 110.25(2)°, V = 3905.4(11) ų, Z = 4, and d _calc = 1.630 g/cm.³ The X-ray structure of Fe₂(CO)₆(₃-S)₂Ni(dppf) exhibits an Fe₂S₂Ni arachno polyhedral core, with the pendant dppf ligand attached to an essentially square planar Ni center. The redox chemistry of Fe₂(CO)₆(₃-S)₂Ni(dppf) was investigated by cyclic voltammetry which showed a reversible, one-electron oxidation localized on the Fe₂S₂ core along with an irreversible, one-electron reduction that is antibonding with respect to the Fe—Fe and Fe—S bonds. The electrochemical assignments were confirmed by carrying out extended Hückel MO calculations on the model cluster Fe₂(CO)₆(₃-S)₂Ni(H₄-dppf).     

Synthesis and crystal structure of the two-dimensional coordination polymer catena(bis(μ3-iodo)-(μ 2-pyrazine)-di-copper(I))

The two-dimensional coordination polymer [Cu₂ i ₂(pyz)]_n (where pyz = pyrazine) has been synthesized hydrothermally and structurally characterized by single crystal X-ray diffraction analysis. [Cu₂ i ₂(pyz)]_n crystallizes in the space group P with a = 4.1759(4) Å, b = 7.1281(7) Å, c = 8.1279(8) Å, = 109.607(2), = 101.769(2), = 96.676(2), and Z = 1. The sheet-like polymer is characterized by infinite stair step [Cu₂ i ₂]_n double chains connected in two dimensions through bridging pyrazine ligands. The coordination environment about each copper is approximately tetrahedral having three Cu–I bonds and a single Cu–N bond.     

Igor’ Grigor’evich Chistyakov (1929–1982) (On the occasion of his 80th birthday)

Memorial Data

Igor’ Grigor’evich Chistyakov (1929–1982) (On the occasion of his 80th birthday)     

PhPMe2 ligand substitution in the tetracobalt cluster Co4(CO)10(μ4-PPh)2: X-ray diffraction structure of Co4(CO)8(PPhMe2)2(μ4-PPh)2

The thermal substitution chemistry of the tetracobalt cluster Co₄(CO)₁₀(₄-PPh)₂ with the phosphine ligand PhPMe₂ (2.5 equiv) has been explored and found to afford the bis(phosphine)-substituted cluster Co₄(CO)₈(PPhMe₂)₂(₄-PPh)₂ as the major reaction product. The regiochemistry and stereoselectivity exhibited by the two phosphine ligands in Co₄(CO)₈(PPhMe₂)₂(₄-PPh)₂ have been unambiguously established by X-diffraction analysis as having a 1,3-cis orientation. Co₄(CO)₈(PPhMe₂)₂(₄-PPh)₂ crystallizes in the monoclinic space group P2₁/n,a=10.314(1) Å,b=18.051(3) Å,c=21.313(2) Å, =90.10(1)°,V=3968.0(8) ų,Z=4,d _calc=1.590 g cm^–3;R=0.051,R _w=0.042 for 4987 observed reflections withI>3(I). Generalizations concerning the stereochemical disposition of two P-ligands about the Co₄(CO)₈P₂(₄-PPh)₂ (where P=phosphine or phosphite) polyhedron are discussed with respect to the cone angle of the P-ligand and its steric interactions with the capping phenylphosphinidene group.     

Antimicrobial Activity of Composite Hydrogels in the Poly(N-vinylpyrrolidone)–RE(NO3)3 · xH2O (RE Are Rare-Earth Ions) System

Crystallography Reports - The bactericidal and bacteriostatic properties (in darkness) of salts RE(NO3)3 · xH2O (RE = La, Ce, Gd, Yb, Y) and composite hydrogels with poly(N-vinylpyrrolidone)...     

Synthesis, spectroscopy, and X-ray structure of the polymer catena-[bis(azido-N)-copper(II)-μ-bis(2-benzimidazolyl)butane]

The title compound, catena-[bis(azido-N)-copper(II)-(bis(2-benzimidazolyl)butane), [Cu(C₁₈H₁₈N₄)(N₃)₂]_n, was obtained from the reaction of the ligand bis(2-benzimidazolyl)butane and Cu(N₃)₂. The x-ray crystal structure is reported. The compound crystallizes in the monoclinic space group P2₁/c with a = 8.2524(10), b = 12.765(5), c = 9.1125(15) Å, = 106.423(12)°, Z = 2. The Cu(II) ions are square-planar coordinated with trans-oriented end-on binding azido ligands. The structure is a polynuclear chain with the benzimidazole bridging at each end. In addition a N_(ligand)-H···N_(azido) H-bridge [N_(ligand)···N_(azido) = 2.994(7) Å] is present, resulting in a pseudo 2-dimensional lattice. The characteristic azido infrared vibrations are found at 2060 and 2077 cm^–1 (_as(N₃)) and 1284 and 1297 cm^–1 ((N₃)).