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Neven Strukan Marina Cindri Tanja Kajfe Boris Kamenar Gerald Giester 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):e443-e444
The crystal and molecular structure of bis(tetramethylammonium) dichlorotetra‐μ2‐methoxo‐di‐μ2‐oxo‐octooxotetramolybdate(VI), (C4H12N)2[Mo4O10(OCH3)4Cl2], has been determined from X‐ray diffraction data. The crystallographically centrosymmetric anion is built up of four edge‐sharing octahedra, two MoO6 and two MoO5Cl. 相似文献
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Multistage mass spectrometry experiments combined with density functional theory (DFT) calculations were used to examine the gas-phase synthesis and ion-molecule reactions of the organomagnesates [CH(3)MgL(2)](-) (L = Cl and O(2)CCH(3)). Neutral species containing an acidic proton (HX) react with the [CH(3)MgL(2)](-) ions via addition with concomitant elimination of methane to form [XMgL(2)](-) ions. Kinetic measurements combined with DFT calculations revealed reduced reactivity of [CH(3)Mg(O(2)CCH(3))(2)](-) toward water, caused by the bidentate binding mode of acetate, which induces overcrowding of the Mg coordination sphere. The [CH(3)MgL(2)](-) ions reacted with (i) aldehydes with enolizable protons via enolization rather than the Grignard reaction and (ii) CH(3)CO(2)H to complete a catalytic cycle for the decarboxylation of acetic acid. Other electrophilic reagents such as pivaldehyde, benzaldehyde, methyl iodide, and trimethylborate are unreactive. DFT calculations on the competition between enolization and the Grignard reaction for [CH(3)MgCl(2)](-) ions reacting with acetaldehyde suggest that while the latter has a smaller barrier, it is entropically disfavored. 相似文献
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《Journal of Coordination Chemistry》2012,65(15):2356-2370
Technetium dimers Tc2(O2CCH3)4X2 (X =?Cl, Br) were synthesized and studied by X-ray Absorption Fine Structure spectroscopy (XAFS). EXAFS analysis gave for Tc2(O2CCH3)4Cl2: d Tc-Tc =?2.18(1) Å, d Tc–Cl =?2.43(1) Å and for Tc2(O2CCH3)4Br2: d Tc–Tc =?2.19(1) Å, d Tc-Br =?2.63(1) Å. The Tc Tc separations are in agreement with Raman studies while the Tc–X distances are somewhat larger. Comparison with other Tc(III) quadruply bonded dimers indicates that the carboxylate compounds exhibit larger Tc–Tc separations. The effect of the terminal ligand (nature and position) on the Tc–Tc separation is discussed. 相似文献
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Trans-[Cr(NH3)4(H2O)Cl]Cl2 (A) crystallizes in the monoclinic space group P21/m (No. 11) with a = 6.556(1), b = 10.630(5), c = 6.729(2) Å and β = 96.15(3)°. Trans-[Cr(NH3)4Cl2]I (B) has monoclinic C2/m (No. 12) space group and a = 9.877(2), b = 8.497(2), c = 6.047(2) Å and β = 108.98(2)°. Both unit cells contain two formula units. Cr? Cl, Cr? O(H2O) and three independent Cr? N(NH3) distances for A are 2.98(1), 2.023(2), 2.067(2), 2.086(3) and 2.064(3) °. Cr? Cl and Cr? N(NH3) bonds in B are 2.325(1) and 2.071(2) °. All octahedral angles are close to 90 and 180°. Both structures were refined to very low R values. Water molecule from trans-[Cr(NH3)4(H2O)Cl]2+ is hydrogen bonded to both ionic chlorides. Cation and two anions form the motive which repeats itself in the crystal. Cations and anions of the second structure are distributed in layers. Each cation and anion have coordination number eight. 相似文献
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Preparation of trans-[Mo6Cl8]Cl4Br22? Starting from Crystalline [Mo6Cl8]Cl4(H2O)2 and Crystal Structure of [(C6H5)4As]2[Mo6Cl8]Cl4Br2 The synthesis of the title compound is successful if the crystallized [(Mo6Cl8)Cl4(H2O)2] containing the H2O molecules in trans-position reacts with HBr + [(C6H5)4As]Br in ethanol in a heterogeneous reaction. The X-ray structure investigation confirms the existence of discrete trans-Br-substituted cluster anions of composition [(Mo6Cl8)Cl4Br2]2? in the crystal. The reaction in homogeneous solutions proceeds to Br-enriched compounds. [(C6H5)4As]2[(Mo6Cl8)Cl4Br2] crystallizes in the triclinic space group P¯1 with a = 11.071(2), b = 11.418(2), c = 12.813(2) Å, α = 116.10(2), β = 95.27(2) and γ = 94.41(2)° (?133°C). The crystal structure at ?133°C was determined from single crystal X-ray diffraction data (R1 = 0.026). The [(Mo6Cl8)Cl4Br2]2?-anions are not completely ordered but distributed statistically among the three positions which are possible within the limits of the ordered [Mo6Cl8]-cores (ratio 11:5:4). The frameworks of the anions consist of Mo6 cluster units with (slightly distorted) octahedral arrangement of the metal atoms (d(Mo? Mo): 2.600(1) up to 2.614(1) Å), which are coordinated by the halogeno ligands in a square-pyramidal manner. The details of the structure will be discussed and compared with similar [(Mo6X8)Y4] cluster units (X, Y ? Cl, Br). 相似文献
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Phosphoraneiminato Acetate Cluster of Copper and Zinc. Crystal Structures of [Cu4(NPEt3)2(O2CCH3)6] and [Zn4(NPEt3)2(O2CCH3)6] The anhydrous acetates of copper(II) and zinc react with the silylated phosphaneimine Me3SiNPEt3 in dichloromethane at 20 °C forming the mixed phosphoraneiminato acetate clusters [Cu4(NPEt3)2(O2CCH3)6] ( 1 ), which forms emerald crystals, and colourless [Zn4(NPEt3)2 · (O2CCH3)6] ( 2 ). In spite of analogous composition the structures of 1 and 2 are completely different. In the asymmetric unit of 1 three copper atoms of an almost isosceles triangle are linked via two nitrogen atoms of the NPEt3– groups to form a trigonal bipyramidal aggregate. One of these three copper atoms is chelated by an acetate group, another one is connected with the fourth copper atom via three μ2‐O2C–CH3 groups. The asymmetric units are associated via a μ2‐O2C–CH3 group and a μ3‐OC(O)CH3 group at a time so that infinite chains result. In 2 two zinc atoms are linked via the nitrogen atoms of the two NPEt3– groups to form an almost centrosymmetric four‐membered ring. Both nitrogen atoms of the four‐membered ring are connected with another zinc atom each. These zinc atoms again are linked with the zinc atoms of the Zn2N2 four‐membered ring via two μ2‐O2C–CH3 groups each and additionally coordinated with a terminal acetate ligand each. 相似文献
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On Thallium(I)-oxochloromolybdates: Synthesis and Crystal Structures of Tl[MoOCl4(NCCH3)], Tl[Mo2O2Cl7], and Tl2[Mo4O4Cl14] and the Structure of Tl2[MoCl6] Black crystals of Tl2[MoCl6] are formed in the reaction of TlCl with MoOCl3 in a sealed evacuated glass ampoule at 350 °C. The crystal structure analysis shows that Tl2[MoCl6] (cubic, Fm 3¯m, a = 986.35(7) pm) adopts the K2[PtCl6] structure with a Mo–Cl bond length of 236.6 pm. Tl[MoOCl4(NCCH3)] was obtained by the reaction of TlCl with MoOCl3 in acetonitrile in form of yellow, moisture sensitive crystals. The structure (orthorhombic, Cmcm, a = 746.0(1), b = 1463.8(3), c = 857.3(2) pm) is built of Tl+ cations and octahedral [MoOCl4(NCCH3)]– anions in which the acetonitrile ligand is bound in trans position to the oxygen. The reaction of TlCl and MoOCl3 in dichloromethane yields Tl[Mo2O2Cl7] and Tl2[Mo4O4Cl14] as green moisture sensitive crystals. The structure of Tl[Mo2O2Cl7] (orthorhombic, Pmmn, a = 694.3(1), b = 951.9(2), c = 904.7(1) pm) consists of Tl+ cations and dinuclear [Mo2O2Cl7]– anions, with two equidistant chlorine bridges of 248.2 and one longer chlorine bridge of 265.7 pm. The oxygen atoms are located in the trans positions of the longer chloro bridge. The structure of Tl2[Mo4O4Cl14] (triclinic, P1¯, a = 692.8(1), b = 919.6(1), c = 998.9(1) pm, α = 104.94(1)°, β = 90.31(1)°, γ = 108.14(1)°) is build of Tl+ cations and [Mo4O4Cl14]2– anions which form tetramers of distorted octahedral, edgesharing (MoOCl5) units with chlorine atoms in the bridging positions. The oxygen atoms are located in the trans positions of the longest chlorine bridges. 相似文献
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[Mo2(O2CCH3)4] forms optically active complexes in DMSO after addition ofchiral ligands. Bidentate ligands (carboxylic acids, diols, and amino alcohols) but also a primary amine (α-phenylethylamine) were shown to form these complexes. For molar ratios of less than appr. 1.5:1 (ligand to complex) up to 5 Cotton effects (A to E from 600 to 270 nm) can be observed. The signs of those between 300 and 400 nm can be used for empirical determination of absolute configuration of complexing ligands. Bands A-D are assigned to the following transitions: A: mainly πMo-Mo→ δ* (A1g→ Eg); B: δ →ρ*Mo-O (A1g → A2g C: mainly δ → π*Mo-Mo (A1g → Eg ) D: δ → δ* (A1g → A2u ). Sector rules for the pair of CD-bands A/C (hexadecant rule) and for CD-band B (hexadecant rule with two additional nodal planes through the MoO4- planes) are derived from qualitative MO theory. 相似文献
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New Phosphido-bridged Multinuclear Complexes of Ag and Zn. The Crystal Structures of [Ag3(PPh2)3(PnBu2tBu)3], [Ag4(PPh2)4(PR3)4] (PR3 = PMenPr2, PnPr3), [Ag4(PPh2)4(PEt3)4]n, [Zn4(PPh2)4Cl4(PRR′2)2] (PRR′2 = PMenPr2, PnBu3, PEt2Ph), [Zn4(PhPSiMe3)4Cl4(C4H8O)2] and [Zn4(PtBu2)4Cl4] AgCl reacts with Ph2PSiMe3 in the presence of tertiary Phosphines (PnBu2tBu, PMenPr2, PnPr3 and PEt3) to form the multinuclear complexes [Ag3(PPh2)3(PnBu2tBu)3] 1 , [Ag4(PPh2)4(PR3)4] (PR3 = PMenPr2 2 , PnPr3 3 ) and [Ag4(PPh2)4(PEt3)4]n 4 . In analogy to that ZnCl2 reacts with Ph2PSiMe3 and PRR′2 to form the multinuclear complexes [Zn4(PPh2)4Cl4(PRR′2)2] (PRR′2 = PMenPr2 5 , PnBu3 6 , PEt2Ph 7 ). Further it was possible to obtain the compounds [Zn4(PhPSiMe3)4Cl4(C4H8O)2] 8 and [Zn4(PtBu2)4Cl4] 9 by reaction of ZnCl2 with PhP(SiMe3)2 and tBu2PSiMe3, respectively. The structures were characterized by X-ray single crystal structure analysis. Crystallographic data see “Inhaltsübersicht”. 相似文献
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When peroxotetramolybdophosphate, [(n-C4H9)4N]3[PO4[Mo2O2(mu-O2)2(O2)2]2], denoted (NBu4)3PMo4, and its tungsten(VI) analogue, (NBu4)3PW4, are mixed in acetonitrile at room temperature, redistribution occurs with the formation of three mixed-addenda species [PO4[Mo4-xWxO20]]3- (x = 1-3). The temperature dependence of the phosphorus-31 NMR spectra of a 1 1 mixture and of the pure salts, (NBu4)3PMo4 or (NBu4)3PW4, shows that [MO(O2)2] species are in chemical exchange, as are the [MOp] units of certain heteropolyacids (e.g. H3[PMo12O40] x aq and H3[PW12O40] x aq). However, there is no chemical exchange between free phosphate and [MO(O2)2] species in these systems; but there is fluxional behaviour involving PMo2W2, PMo4 and PW4. This is attributed to the rapid equilibrium between isomers (PMo2W2) and to equilibrium between anionic structures with tridentate (mu-eta2:eta1-O22-) and bidentate (eta2-O22-) modes of coordination for the two peroxo groups of the [M2O2(mu-O2)2(O2)2] moieties. 相似文献
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Nitrosyl Complexes of Molybdenum (+II). Crystal Structures of [Mo(NO)Cl3 · POCl3]2 and [AsPh4]2[Mo(NO)Cl5] · 2 CH2Cl2 Solutions of MoCl5 in POCl3 react with NOCl forming the nitrosyl compound Mo(NO)Cl3 · 2POCl3 ( I ), which in CH2Cl2 cleaves off one solvate molecule, yielding the dimeric complex [Mo(NO)Cl3 · POCl3]2 ( II ). Reaction with AsPh4Cl in dichloro methane leads to the nitrosyl complexes AsPh4[Mo(NO)Cl4] · CH2Cl2 ( III ) and [AsPh4]2[Mo(NO)Cl5] · 2CH2Cl2 ( IV ), respectively. The i.r. spectra are recorded and assigned. [Mo(NO)Cl3 · POCl3]2 crystallizes monoclinic in the space group P21/c with two dimeric units per unit cell. The crystal structure was determined by X-ray diffraction methods (R = 0.040; 1391 observed, independent reflexions). Complex II is linked by chlorine bridges, forming a dimeric, centrosymmetric molecule of symmetry Ci. The N? O bond of the nitrosyl ligand is extremely short (108 pm), the Mo? N bond (181 pm) corresponds to a double bond. In trans position to the NO ligand, which is coordinated in linear array, there is the O atom of the solvate molecule POCl3. [AsPh4]2[Mo(NO)Cl5] · 2 CH2Cl2 crystallizes triclinic in the space group P1 with two units per unit cell (R = 0.039; 1967 observed, independent reflexions). The molybdenum atom is coordinated octahedrally by five Cl ligands and a nitrosyl group, as well coordinated in linear array (Mo? N? O 174°). The nitrosyl ligand exerts a significant trans-effect (r Mo? Cl(trans) = 247 pm, r MoCl4(eq)(average) = 239 pm). 相似文献