Synthesis and Structure of a Novel Mg6 Cluster Molecule Mg6(μ3-OH)2(μ3-Br)2(μ-Br)8(THF)8

A novel Mg₆ cluster molecule with the formula of Mg₆( ₃-OH)₂( ₃-Br)₂(-Br)₈(THF)₈ (1) has been isolated in 38% yield from a reaction of the Grignard reagent, 2-naphthyl-Mg-Br with BBr₃ in THF. The structure of 1, determined by a single-crystal X-ray diffraction analysis, contains two Mg₃ triangles linked together by two bridging bromide ligands. Within each Mg₃ triangle, one hydroxide and one bromide ligand function as triply bridging ligands capping both sides of the Mg₃ triangle. The coordination geometry around each Mg(II) ion is approximately octahedral. NMR studies revealed that compound 1 is highly fluxional in solution.     

Dinuclear Ruthenium(II) Carbonyl Complexes Doubly Bridged by a Bromine Atom and a C5H3N-2-C(O)CH2-6-CH2 (Q) Group. Crystal Structures of Ru2(μ-Br)(μ-Q)Br(CO)4(PPh3)(MeOH) and Ru2(μ-Br)(μ-Q)Br(CO)3(PPh3)2

The oxidative addition reaction of 2,6-bis(bromomethyl)pyridine to Ru₃(CO)₁₂ gave scarcely soluble {Ru₂Br₂(-Q)(CO)₄} _n , 1, [Q=C₅H₃N-2-C(O)CH₂-6-CH₂] or a mixture of 1 and the mononuclear complex RuBr(Q)(CO)₃, 2, [Q=C₅H₃N-2-C(O)CH₂-6-CH₂Br] according to the reactant's mole ratio. Further reactions of 1 with some N- and P-donor ligands (L) afforded readily soluble dinuclear complexes, Ru₂(-Br)(-Q)Br(CO) _n (L) _m [n=4, m=1, L=PPh₃ 3a, or py 3b; n=3, m=2, L=PPh₃ 5a, or PPh₂(o-tolyl) 5b]. In this paper, the characterization of these products by the elemental analyses and the spectroscopic methods are described. The X-ray crystal structures of Ru₂(-Br) (-Q)Br(CO)₄(PPh₃)(MeOH), 4, which was obtained by crystallization of 3a from MeOH, and of 5a · (2CHCl ₃ ) are also described. Each of the metal atoms in 4 has a distorted octahedral coordination, while in 5a · (2CHCl ₃ ) one metal atom takes a distorted octahedral geometry and the other pseudooctahedral, which is completed by presenting a Ru ··· Br secondary bonding interaction.     

Synthesis and molecular and crystal structure of the octanuclear palladium cluster Pd8(μ3-CO)2(μ2-CO)6(PMe3)7

Treatment of bis(dibenzylideneacetone)palladium with trimethylphosphine under a carbon monoxide atmosphere gives the title complex in good yield. X-ray crystallography has shown the structure of the complex to consist of an octahedron of palladium atoms which is bicapped by two further palladium atoms in an asymmetric fashion. Seven of the eight palladium centres carry terminal trimethylphosphine ligands. Two face-bridging and six edge-bridging CO molecules complete the ligand shell.     

Crystal structures of the selenium- and bromo-bridged copper(I) dimers [Cu2(μ2-Br)2(SePPh3)2 · (NCCH3)2] and [Cu2I2(μ3-dppm-Se,Se)2] · 2CH3CN

Reactions of copper(I) halides with Se-donor ligands, namely, triphenylphosphine selenide (Ph₃PSe) and bis(diphenylselenophosphinyl)methane (dppm-Se,Se) yielded bromo-bridged [Cu₂(μ₂-Br)₂(SePPh₃)₂(NCCH₃)₂] (1), and selenium-bridged, [Cu₂I₂(μ₃-dppm-Se,Se)₂]?· 2CH₃CN (2) dimers, whose crystal structures are described. Acetonitrile stabilizes 1 by coordinating and helps to stabilize the packing in crystals of 2.     

Binary palladium carboxylates with electron-donating and electron-withdrawing substituents in the carboxylate ligand: Synthesis and structural studies. The crystal structures of Pd3(μ-CH2ClCO2)6 · CH2Cl2, Pd3(μ-C6H11CO2)6, and Pd3(μ-CMe3CO2)6

Replacement of the acetate ligands in Pd₃(μ-MeCO₂)₆ in benzene gave complexes of the general formula Pd₃(μ-RCO₂)₆ (R = CF₃, CCl₃, CH₂Cl, Me, cyclo-C₆H₁₁, and CMe₃). The structures of the complexes were determined using IR spectroscopy, ESI mass spectrometry, and X-ray diffraction. It was found that the complexes contain a trinuclear Pd framework and that their spectroscopic and structural parameters depend on the donor-acceptor properties of the substituent in the carboxylate ligand.     

Synthesis and structure of the organoantimony peroxide solvates [Sb4(μ2-O)4(O2)2(C6H3MeO-2,Br-5)8]·1.5C4H8O2 and [Sb4(μ2-O)4(O2)2(C6H3MeO-2,Br-5)8]·6C4H8O2

The organoantimony peroxide (Ar₂SbO)₄(O₂)₂ (Ar = C₆H₃OMe-2, Br-5) was synthesized by the oxidation of Ar3Sb with hydrogen peroxide in the presence or acetoxime or acetophenone oxime in dioxane. The product crystallizes with various content of the solvent molecules in the crystal unit cell [1.5 (I) and 6 (II), respectively]. An X-ray diffraction analysis of the solvates was performed. Four antimony atoms in the peroxide are in the octahedral coordination, and are linked through bridging oxygen atoms and two peroxide groups. The distances Sb-C, Sb-O_bridge, Sb-O_peroxide, O-O and Sb...Sb are 2.117–2.122, 1.960–1.972, 2.193–2.235, 1.461, 1.465 and 3.223–3.237 Å in I, and 2.112, 2.119, 1.957, 1,966, 2.204, 2,246, 1,467, and 3.2439 Å in II.     

Syntheses, X-ray structural characterizations, and thermal stabilities of two nonclassical trinuclear vanadium(IV) complexes, (V3(μ3-O)O2)(μ2-O2P(CH2C6H5)2)6(H2O) and (V3(μ3-O)O2)(μ2-O2P(CH2C6H5)2)6(py), and polymeric complexes of stoichiometry (VO(O2PR2)2)∞, R2 = Ph2 and o-(CH2)2(C6H4)

The preparation and structural characterization of two trinuclear vanadium complexes, (V(3)(μ(3)-O)O(2))(μ(2)-O(2)P(CH(2)C(6)H(5))(2))(6)(H(2)O), 1, and (V(3)(μ(3)-O)O(2))(μ(2)-O(2)P(CH(2)C(6)H(5))(2))(6)(py), 2, are reported. In these nonclassical structures, the planar central core consists of the three vanadium atoms arranged in the form of an acute quasi-isosceles triangle with the central oxygen atom multiply bonded to the vanadium atom at the center of the vertex angle and weakly interacting with the two other vanadium atoms on the base sites, each of which contain one external multiply bonded oxygen atom. Reacting VO(acac)(2)in the presence of diphenylphosphinic acid affords (VO(O(2)PPh(2))(2))(∞), 3, while 2-hydroxyisophosphindoline-2-oxide at room temperature in CH(2)Cl(2) affords ((H(2)O)VO(O(2)Po-(CH(2))(2)C(6)H(4))(2))(∞), 4, and at 120 °C in EtOH yields (VO(O(2)P(o-(CH(2))(2)(C(6)H(4)))(∞), 5 on the basis of elemental analyses. The thermal and chemical stability of the complexes were assessed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements. The bond strengths of the vanadium atoms to the OH(2) ligand in 1 and to the NC(5)H(5) ligand in 2 were assessed at 10.7 and 42.0 kJ/mol respectively. Room temperature magnetic susceptibility measurements reveal magnetic moments for trinuclear 1 and 2 at 3.02(1) and 3.05(1) μ(B/mol), and also close to spin only values (1.73 μ(B)) values for 3, 4, and 5 at 1.77(2), 1.758(7), and 1.77(3) μ(B), respectively. Variable-temperature, solid-state magnetic susceptibility measurements were conducted on complex 2 in the temperature range of 2.0-298 K and at an applied field of 0.5 T. Magnetization measurements at 2 and 4 K confirmed a very weak magnetic interaction between the vanadyl centers.     

Four [Tp*W(μ3-S)3Cu3(μ3-Br)]-based clusters: synthesis, structural characterization and third-order NLO properties

Treatment of [Et(4)N][Tp*W(μ(3)-S)(3)(CuBr)(3)] (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) (1) with an excess of α-methylpyridine (α-MePy) and NH(4)PF(6) in CH(2)Cl(2) afforded a cationic cluster [Tp*W(μ(3)-S)(3)Cu(3)(α-MePy)(3)(μ(3)-Br)](PF(6)) (2) while the reaction of 1 with an excess of 1,4-pyrazine (1,4-pyz) and NH(4)PF(6) in MeCN-CH(2)Cl(2) at 65 °C produced a polymeric cluster [Tp*W(μ(3)-S)(3)Cu(3)(1,4-pyz)((1,4-pyz)(0.5))(2)(μ(3)-Br)][Tp*W(μ(3)-S)(3)(CuBr)(3)] (3). Reactions of 1 with melamine (MA) in 1:1 or 1:2 gave rise to another polymeric cluster [{Tp*W(μ(3)-S)(3)Cu(3)Br(μ(3)-Br)}(2)(MA)(2)] (4) and a neutral cluster [Tp*W(μ(3)-S)(3)Cu(3)Br(μ(3)-Br)(MA)(2)] (5), respectively. Compounds 2-5 were characterized by elemental analysis, IR spectra, UV-vis spectra, (1)H NMR, electrospray ionization (ESI) mass spectra and X-ray crystallography. The cation of 2 has a cubane-like [Tp*W(μ(3)-S)(3)Cu(3)(μ(3)-Br)] structure with each α-MePy ligand coordinated at one Cu(i) center. For 3, each [Tp*W(μ(3)-S)(3)Cu(3)(μ(3)-Br)] core is interconnected by 1,4-pyz bridges to form a 1D cationic zigzag chain with the [Tp*W(μ(3)-S)(3)(CuBr)(3)](-) anions arranged along its two sides. For 4, each [Tp*W(μ(3)-S)(3)Cu(3)(μ(3)-Br)] core is interlinked by MA bridges to afford a 1D spiral chain. 5 adopts a cubane-like [Tp*W(μ(3)-S)(3)Cu(3)(μ(3)-Br)] structure in which one terminal Br and two MA ligands are coordinated at three Cu centers. The third-order nonlinear optical (NLO) properties of 1-5 in DMF were investigated by femtosecond degenerate four-wave mixing (DFWM) technique with a 80 fs pulse width at 800 nm. Compounds 1-5 exhibit good NLO responses, and 3 and 4 possess the largest second-order hyperpolarizability γ values among the known W/Cu/S clusters bearing the [Tp*WS(3)] unit.     

Comparison of the Bonding of Benzene and C60 to a Metal Cluster: Ru3(CO)9(μ3-η2,η 2,η2-C6H6) and Ru3(CO)9(μ3-η2,η2,η2-C60)

The electron distributions and bonding in Ru₃(CO)₉( ³- ², ², ²-C₆H₆) and Ru₃(CO)₉( ³- ², ², ²-C₆₀) are examined via electronic structure calculations in order to compare the nature of ligation of benzene and buckminsterfullerene to the common Ru₃(CO)₉ inorganic cluster. A fragment orbital approach, which is aided by the relatively high symmetry that these molecules possess, reveals important features of the electronic structures of these two systems. Reported crystal structures show that both benzene and C₆₀ are geometrically distorted when bound to the metal cluster fragment, and our ab initio calculations indicate that the energies of these distortions are similar. The experimental Ru–C_fullerene bond lengths are shorter than the corresponding Ru–C_benzene distances and the Ru–Ru bond lengths are longer in the fullerene-bound cluster than for the benzene-ligated cluster. Also, the carbonyl stretching frequencies are slightly higher for Ru₃(CO)₉( ³- ², ², ²-C₆₀) than for Ru₃(CO)₉( ³- ², ², ²-C₆H₆). As a whole, these observations suggest that electron density is being pulled away from the metal centers and CO ligands to form stronger Ru–C_fullerene than Ru–C_benzene bonds. Fenske-Hall molecular orbital calculations show that an important interaction is donation of electron density in the metal–metal bonds to empty orbitals of C₆₀ and C₆H₆. Bonds to the metal cluster that result from this interaction are the second highest occupied orbitals of both systems. A larger amount of density is donated to C₆₀ than to C₆H₆, thus accounting for the longer metal–metal bonds in the fullerene-bound cluster. The principal metal–arene bonding modes are the same in both systems, but the more band-like electronic structure of the fullerene (i.e., the greater number density of donor and acceptor orbitals in a given energy region) as compared to C₆H₆ permits a greater degree of electron flow and stronger bonding between the Ru₃(CO)₉ and C₆₀ fragments. Of significance to the reduction chemistry of M₃(CO)₉( ³- ², ², ²-C₆₀) molecules, the HOMO is largely localized on the metal–carbonyl fragment and the LUMO is largely localized on the C₆₀ portion of the molecule. The localized C₆₀ character of the LUMO is consistent with the similarity of the first two reductions of this class of molecules to the first two reductions of free C₆₀. The set of orbitals above the LUMO shows partial delocalization (in an antibonding sense) to the metal fragment, thus accounting for the relative ease of the third reduction of this class of molecules compared to the third reduction of free C₆₀.     

Syntheses and characterization of the vanadium trimer (V3(μ3-O)O2)(μ2-O2P(CH2C6H5)2)6(4,4′-bipyridine) and the vanadium hexamer [(V3(μ3-O)O2)(μ2-O2P(CH2C6H5)2)6]2(μ2-N1,N2-di(pyridin-4-yl)oxalamide)

Reacting VO(acac)₂ with six equivalents of dibenzylphosphinic acid in the presence of 4,4′-bipyridine or μ₂-N¹,N²-di(pyridin-4-yl)oxalamide leads to trimeric (V₃(μ₃-O)O₂)(μ₂-O₂P(CH₂C₆H₅)₂)₆(4,4′-bipyridine) or the hexamer [(V₃(μ₃-O)O₂)(μ₂-O₂P(CH₂C₆H₅)₂)₆]₂(μ₂-N¹,N²-di(pyridin-4-yl)oxalamide). The complexes were characterized by spectroscopic (FTIR and ¹H NMR spectroscopies), TGA, and by single crystal X-ray diffraction measurements. The structures consist of a planar central core where three vanadium ions are arranged in the form of a quasi-isosceles triangle and contain an interstitial O which is multiply bonded to one V and weakly interacting at different bond distances to the remaining two V ions.     

Synthesis and Molecular and Crystal Structure of K4.5{[Mo3(μ3-Te)(μ2-Te2)3(CN)6]I}I1.5·3H2O and Cs3{[Mo3(μ3-Te)(μ2-Te2)3(CN)6]I}·2H2O

Crystal structures of two new compounds containing trigonal tellurium-bridged cluster fragments [Mo₃(₃-Te)(₂-Te₂)₃]⁴⁺ were investigated. Crystal data for K_4.5{[Mo₃(₃-Te)(₂-Te₂)₃(CN)₆]I}I_1.5·3H₂O: space group , Z = 4, a = 13.280(1), c = 23.800(3) , V = 3635.0(6) ³, d _calc = 3.432 g/cm³, R ₁ = 0.0335, wR2 = 0.0912 for 1378 I _hkl > 2 _I from 3545 measured I _hkl ; for Cs₃{[Mo₃(₃-Te)(₂-Te₂)₃(CN)₆]I}·2H₂O: space group P2 ₁ /n, Z = 2, a= 9.650(2) , b = 22.297(5), c = 27.446(7) , = 94.10(2)°, V = 5890(2) ³, d _calc = 4.273 g/cm ³, R ₁ = 0.0384, wR ₂ = 0.0744 for 957 I _hkl > 2 _I from 3758 measured I _hkl (Enraf-Nonius CAD-4 diffractometer, MoK , graphite monochromator). In both compounds, ionic pairs {[Mo₃Te₇(CN)₆]I}^3– with Te_ax...I^– distances of 3.358-3.676 are formed. In the potassium salt, the {[Mo₃Te₇(CN)₆]I}^3– anion pairs are linked by the additional Te_eqI^– short contacts of 3.460 into two-dimensional corrugated layers perpendicular to the c axis of the unit cell. The structure of the cesium salt is ionic with interstitial H₂O molecules and double-layer closest packing of anions.     

Probing the aromaticity of the [(H(t)Ac)3(μ2-H)6], [(H(t)Th)3(μ2-H)6],(+), and [(H(t)Pa)3(μ2-H)6] clusters

In this study we report about the aromaticity of the prototypical [(H(t)Ac)(3)(μ(2)-H)(6)], [(H(t)Th)(3)(μ(2)-H)(6)](+), and [(H(t)Pa)(3)(μ(2)-H)(6)] clusters via two magnetic criteria: nucleus-independent chemical shifts (NICS) and the magnetically induced current density. All-electron density functional theory calculations were carried out using the two-component zeroth-order regular approach and the four-component Dirac-Coulomb Hamiltonian, including scalar and spin-orbit relativistic effects. Four-component current density maps and the integration of induced ring-current susceptibilities clearly show that the clusters [(H(t)Ac)(3)(μ(2)-H)(6)] and [(H(t)Th)(3)(μ(2)-H)(6)](+) are non-aromatic whereas [(H(t)Pa)(3)(μ(2)-H)(6)] is anti-aromatic. However, for the thorium cluster we find a discrepancy between the current density plots and the classification through the NICS index. Our results also demonstrate the increasing influence of f orbitals, on bonding and magnetic properties, with increasing atomic number in these clusters. We think that the enhanced electron mobility in [(H(t)Pa)(3)(μ(2)-H)(6)] is due the significant 5f character of its valence shell. Also the participation of f orbitals in bonding is the reason why the protactinium cluster has the shortest bond lengths of the three clusters. This study provides another example showing that the magnetically induced current density approach can give more reliable results than the NICS index.     

STRUCTURAL STUDIES OF THE COPPER(II) ACETATE COMPLEXES Cu(o2CCH3)2(pyridine)3 AND Cu6(μ-O2CCH3)4(μ4-O2CCH3)2(μ-OCMe3)6

Abstract

[Cu(O₂CCH₃)₂]₂, 1, reacts with pyridine to form violet-blue Cu(O₂CCH₃)₂(pyridine)₃, 2, in > 90% yield. 2 crystallizes from pyridine with a distorted square-pyramidal geometry around copper with the monodentate acetate ligands located diagonally in the basal positions. 1 reacts with Bi(OCMe₃)₃ in THF to form blue Cu₆(μ-O₂CCH₃)₄(μ₄-O₂CCH₃)₂(μ-OCMe₃)₆, 3. 3 crystallizes from THF/hexanes with a hexagon of copper atoms linked by six doubly-bridging tert-butoxide ligands, four doubly-bridging bidentate acetates, and two quadruply-bridging bidentate acetate ligands.     

Synthesis, Structure and Properties of a Copper Complex Cu2(μ-PhCOO)2(μ-CH3COO)2(CH3OH)2

The title complex Cu2(μ-PhCOO)2(μ-CH3COO)2(CH3OH)2 1(C20H24Cu2O10, Mr=structure was determined by X-ray diffraction method. Complex 1 belongs to orthorhombic, space group Pbca with a = 13.083(6), b = 8.078(4), c = 21.566(2)(A), V = 2279(2) (A)3, Z = 4, Dc= 1.607g/cm3, F(000) = 1128,μ(MoKa) = 1.918 mm-1, the final R = 0.0506 and wR = 0.1382. Each Cu(Ⅱ)ion is coordinated by five oxygen atoms from two benzoic acids, two acetic acids and one methanol molecule in a slightly distorted square pyramidal environment. The title molecules construct a 2-D complex 1 displays strong emissions. IR and TG-DTA studies are also presented.     

Novel heterobimetallic complexes with S2CPR3(κ-S,S′)(κ-S,C,S′) bridges. X-Ray structure of [MnMo(CO)6(μ-Br)-(μ-S2CPiPr3)]

Reaction of fac-[Mn(CO)₃(S₂CPR₃)(Br)] with [Mo(CO)₃(NCMe)₃] produces a member of a novel class of heterodinuclear complex [MnMo(CO)₆(μ-Br)(μ-S₂CPR₃)] (R = Cy, ⁱPr), which contains S₂CPR₃ bridging ligands, acting as an (κ-S,S′) chelate towards Mn, and as an (κ-S,C,S′) pseudoallyl group to Mo, without a direct MoMn bond. One carbonyl group in [MnMo(CO)₆(μ-Br)(μ-S₂CPR₃)] can be easily displaced at room temperature by neutral ligands such as PEt₃ and P(OMe)₃, affording pentacarbonyl complexes, [MnMo(CO)₅(L)(μ-Br)(μ-S₂CPR₃].     

CRYSTAL AND MOLECULAR STRUCTURE OF A NOVEL Au Ag SUPRACLUSTER COMPOUND [Au_13Ag_12(μ-Br)_4(μ_3-Br)_2(Ph_3P)_10-

<正> [Au13Ag12(μ-Br)1(μ3-Br)2 (Ph3P)10Br2] Br, monoclinic. space group C2/m, a = 36. 496(17). b=16. 878(7), c-=19. 772(9) A , β=99. 87(5)°, V=11998. 9 A3.Z=2. The final R(Rw) is 0. 097(0. 109) for 3779 reflections with I>3σ(I). The structure can he considered as two icosahedral cluster units (AurAg6) sharing one vertex and linked hy six bromine atoms. The Au - Au, Au - Ag. and Ag-Ag distances fall in the ranges of 2. 69-2. 96. 2. 84-3. 02. and 2. 92-3. 26 A, respectively.     

Syntheses,crystal structures,and electrochemical studies of Fe2(CO)6(μ-PPh2)(μ-L) (L = OH,OPPh2, PPh2)

Reaction of Fe₃(CO)₁₂ and Ph₂PH in the presence of Et₃N in THF at 0?°C immediately forms Fe₂(CO)₆(μ-PPh₂)(μ-OH) (1), Fe₂(CO)₆(μ-PPh₂)(μ-k²O,P-OPPh₂) (2), and Fe₂(CO)₆(μ-PPh₂)₂ (3) in yields of 25, 14, and 19%, respectively. Experiments confirm that Et₃N shortens the reaction time. The absence of O₂ hinders the formation of 2. The presence of H₂O can increase the yield of 1. Their structures have been determined by X-ray crystallography and the complexes have been completely characterized by EA, IR, and ¹H, ¹³C, ³¹P NMR. Electrochemical studies reveal that they exhibit catalytic H₂-producing activities.