The reaction of Sn[CH(SiMe3)2]2 with ethyne: formation of (HCC)Sn[CH(SiMe3)2]2(μ-trans-CHCH)Sn[CH-(SiMe3)2]2(CHCH2)

The reaction of Sn[CH(SiMe₃)₂]₂ and ethyne at ambient temperature affords a mixture of products, from which the title compound has been separated and identified by IR, ¹H, and ¹³C NMR spectroscopy.     

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.     

Complexes [Ni2(μ-OH2)(μ-O2CCH(CH3)2)2L2–4((CH3)2CHCO2)2]: Synthesis,Structure, and Mass Spectrometric Studies

Russian Journal of Coordination Chemistry - Three new binuclear aqua-bridged nickel(II) 2-methylpropionate complexes [Ni2(μ-OH2)(μ-O2CCH(CH3)2)2L2–4((CH3)2CHCO2)2] (L is...     

NMR study of ligand exchange and electron self-exchange between oxo-centered trinuclear clusters [Fe3(μ3-O)(μ-O2CR)6(4-R'py)3](+/0)

The syntheses, single crystal X-ray structures, and magnetic properties of the homometallic μ?-oxo trinuclear clusters [Fe?(μ?-O)(μ-O?CCH?)?(4-Phpy)?](ClO?) (1) and [Fe?(μ?-O)(μ-O?CAd)?(4-Mepy)?](NO?) (2) are reported (Ad = adamantane). The persistence of the trinuclear structure within 1 and 2 in CD?Cl? and C?D?Cl? solutions in the temperature range 190-390 K is demonstrated by 1H NMR. An equilibrium between the mixed pyridine clusters [Fe?(μ?-O)(μ-O?CAd)?(4-Mepy)(3-x)(4-Phpy)(x)](NO?) (x = 0, 1, 2, 3) with a close to statistical distribution of these species is observed in CD?Cl? solutions. Variable-temperature NMR line-broadening made it possible to quantify the coordinated/free 4-Rpy exchanges at the iron centers of 1 and 2: k(ex)2?? = 6.5 ± 1.3 × 10?1 s?1, ΔH(?) = 89.47 ± 2 kJ mol?1, and ΔS(?) = +51.8 ± 6 J K?1 mol?1 for 1 and k(ex)2?? = 3.4 ± 0.5 × 10?1 s?1, ΔH(?) = 91.13 ± 2 kJ mol?1, and ΔS(?) = +51.9 ± 5 J K?1 mol?1 for 2. A limiting D mechanism is assigned for these ligand exchange reactions on the basis of first-order rate laws and positive and large entropies of activation. The exchange rates are 4 orders of magnitude slower than those observed for the ligand exchange on the reduced heterovalent cluster [Fe(III)?Fe(II)(μ?-O)(μ-O?CCH?)?(4-Phpy)?] (3). In 3, the intramolecular Fe(III)/Fe(II) electron exchange is too fast to be observed. At low temperatures, the 1/3 intermolecular second-order electron self-exchange reaction is faster than the 4-Phpy ligand exchange reactions on these two clusters, suggesting an outer-sphere mechanism: k?2?? = 72.4 ± 1.0 × 103 M?1 s?1, ΔH(?) = 18.18 ± 0.3 kJ mol?1, and ΔS(?) = -90.88 ± 1.0 J K?1 mol?1. The [Fe?(μ?-O)(μ-O?CCH?)?(4-Phpy)?](+/0) electron self-exchange reaction is compared with the more than 3 orders of magnitude faster [Ru?(μ?-O)(μ-O?CCH?)?(py)?](+/0) self-exchange reaction (ΔΔG(exptl)(?298) = 18.2 kJ mol?1). The theoretical estimated self-exchange rate constants for both processes compare reasonably well with the experimental values. The equilibrium constant for the formation of the precursor to the electron-transfer and the free energy of activation contribution for the solvent reorganization to reach the electron transfer step are taken to be the same for both redox couples. The larger ΔG(exptl)(?298) for the 1/3 iron self-exchange is attributed to the larger (11.1 kJ mol?1) inner-sphere reorganization energy of the 1 and 3 iron clusters in addition to a supplementary energy (6.1 kJ mol?1) which arises as a result of the fact that each encounter is not electron-transfer spin-allowed for the iron redox couple.     

Further studies of M3(μ3-O)(μ-X)3(μ-O2CCH3)3L3 (M=Mo,W) type clusters with nine core electrons

Four new compounds having nine cluster electrons and cores of the types Mo₃OCl₃, Mo₃OBr₃, and W₃OCl₃ are reported. Compound (1) prepared by reduction of [Bu₄N][Mo₃OCl₆(OAc)₃] in THF with metallic zinc, was shown by X-ray crystallography to be Mo₃OCl₄(OAc)₃ (THF)₂ (1). It forms crystals in space groupP2₁ with unit cell dimensionsa=9.472(2) Å,b=13.546(4) Å,c=9.652(2) Å, =101.70(2)°,V=1201(1) Å₃,Z=2. The [Mo₃(₃-O)(-Cl)₃]⁴⁺ core is surrounded by three -O₂CCH₃ anions, one Cl^–, and two THF and has Mo-Mo distances of 2.620(1) Å, 2.613(1) Å, and 2.530(1) Å, with the shortest bond between the two Mo atoms to which the THF molecules are coordinated. Compounds [Bu₄N]₂ [Mo₃OBr₆(O₂CCH₃)₃] · Me₂CO, (2) and [Mo₃OBr₃(O₂CCH₃)₃(PMe₃)₃]₃ · BF₄, (3) are the first two nine-electron Mo₃ species with a [Mo₃(₃-O) Br₃]⁴⁺ core. Both were obtained by zinc reduction of [Mo₃OBr₆(O₂CCH₃)₃]^– in the presence of (NBu₄) Br (2) or PMe₃ and NaBF₄ (3), and each was characterized crystallographically. Compound (2) crystallized in space group Cc with unit cell dimensionsa=25.037(5) Å,b=12.827(2) Å,c=21.484(4) Å, =122.96(1)⁰,V=5790(3) ų,Z=4. While the anion has no crystallographically required symmetry, its virtual symmetry is C_3v . The Mo-Mo distances are 2.619(2) Å, 2.610(3) Å, 2.644(2) Å, with a mean value of 2.624[14] Å. Compound (3) crystallized in space groupP2₁/c with unit cell dimensionsa=10.846(2) Å,b=25.033(5) Å,c=12.641(5) Å, =94.74(2)⁰,V=3420(2) ų,Z=4. The cation occupies a general position but has virtual C_3v symmetry, with Mo-Mo distances of 2.601(2) Å, 2.610(2) Å, 2.627(2) Å, with a mean value of 2.613[14] Å. Thus the anionic and cationic Mo₃ clusters in (2) and (3), respectively, have average Mo-Mo distances that are equal within experimental error. Compound (4), [NEt₄]₂ [W₃OCl₆(O₂CCH₃)₃] is the first 9-electron compound of this type containing tungsten. It was prepared by reduction of [Et₄N][W₃OCl₆(OAc)₃] in benzene with Na/Hg. It crystallized in space groupP2₁2₁2₁ with unit cell dimensionsa=11.076(2) Å,b=14.345(2) Å,c=21.026(3) Å,V=3574(1) ų,Z=4. The anion resides on a general position but has virtual C_3v symmetry, with W-W distances of 2.577(1) Å, 2.612(1) Å, 2.584(1) Å and a mean value of 2.591[15] Å.     

Electronic state dependence of the ion-molecule reaction CH(3)CN(+) + CH(3)CN → CH(4)CN(+) + CH(2)CN: threshold electron-secondary ion coincidence (TESICO) and direct ab initio molecular dynamics study

The ion-molecule reaction, CH(3)CN(+) + CH(3)CN → CH(3)CNH(+) + CH(2)CN, has been investigated using the threshold electron-secondary ion coincidence (TESICO) technique. Relative reaction cross sections for two microscopic reaction mechanisms, i.e., proton transfer (PT) from the acetonitrile ion CH(3)CN(+) to neutral acetonitrile CH(3)CN and hydrogen atom abstraction (HA) by CH(3)CN(+) from CH(3)CN, have been determined for two low-lying electronic states, (2)E and (2)A(1) of the CH(3)CN(+) primary ion. The cross section for PT of the (2)A(1) state was smaller than that of the (2)E state, whereas that of HA are almost the same in the two states. Ab initio calculations showed that the dissociation of the C-H(+) bond of CH(3)CN(+) is easier in the (2)E state than that in the (2)A(1) state. The direct ab initio molecular dynamics (MD) calculations showed that two mechanisms, direct proton transfer and complex formation, contribute the reaction dynamics.     

Syntheses and Crystal Structures of Two Trinuclear Iron(Ⅲ) Carboxylate Complexes: [Fe3(μ3-O)(μ-O2CEt)6(H2O)3]Cl.3H2O and [Fe3(μ3-O)(μ-O2CEt)6Py3]Cl(Py=pyridine)

Two new oxo-centered trinuclear iron complexes [Fe3(μ3-O)(μ-O2CEt)6(H2O)3]Cl.3H2O 1 and [Fe3(μ3-O)(μ-O2CEt)6Py3]Cl 2 were prepared in non-aqueous solvent and their crystal structures have been determined. Crystal 1 is monoclinic, space group P21/n, a=9.909(3), b=24.467(8), c=14.542(7)(), β=107.85(4)° V=3356(4)()3, Z=4, Mr=765.52, Dc=1.52 g/cm3, μ=14.28 cm-1, F(000)=1588 and R=0.059, Rw=0.071 for 3745 unique reflections with I>3σ(I). Crystal 2 belongs to the monoclinic system with space group C2/c, a=13.750(3), b=18.439(4), c=16.696(3)(), β=93.42(3)°, V=4226(3)()3, Z=4, Mr=894.73, Dc=1.41 g/cm3, μ=11.4 cm-1, F(000)=2322 and R=0.058, Rw=0.062 for 2272 unique reflections with I>3σ(I). The two structures contain the same trimetal framework in which three iron(Ⅲ) atoms form a nearly equilateral triangle with a μ3-oxygen atom in the centre.     

Osmium(IV) Binuclear Nonelectrolytic Oxo-Bridged Carboxylates. Molecular Structure of [Os2 IV(μ-O)(μ-O2CCCl3)2Cl4(PPh3)2] · CH2Cl2

The reactions between trans-[Os^VIO₂Cl₂L₂] (L = PPh₃, AsPh₃, SbPh₃) and carboxylic acids RCO₂H (R = CH₃, C(CH₃)₃, CH₂Cl, CCl₃, CF₃) are studied. The resulting binuclear compounds were found to have the general formula [Os₂ ^IV(-O)(-O₂CR)₂Cl₄(L)₂] (L = PPh₃; R = CH₃, C(CH₃)₃, CH₂Cl, CCl₃, CF₃, and L = AsPh₃; R = CH₃, CH₂Cl, CCl₃, CF₃). X-ray diffraction analysis revealed that the [Os₂ ^IV(-O)(-O₂CCCl₃)₂Cl₄(PPh₃)₂] · CH₂Cl₂ complex crystallizes in a triclinic system with space group P ; a = 10.747(2) Å, b = 19.291(4) Å, c = 24.614(5) Å, = 100.08(3)°, = 90.63(3)°, = 97.05(3)°, V = 4983.5(17) ų, Z = 4. The Os(-O)Os angle is 142.2(7)°. The interaction of trans-[Os^VIO₂Cl₂(SbPh₃)₂] with all the acids under study is attended by intramolecular redox reaction resulting in SbCl₂Ph₃.     

三核钼簇合物(Me4N)[Mo3(μ3-O)(μ-Cl)3(μ-O2CH)3Cl3]的制备和晶体结构测定

标题簇合物系通过液相氧化低价钼(MoCl3)制得,晶体属正交晶系,空间群为D2h[16]-Pmnb,晶胞参数:α=11.403(1),b=12.345(2),c=14.292(2)A,V=2011.8(8)A[3].Z=4,Dc=2.396g.cm[-3].使用四圆衍射仪收集衍射数据,晶体结构用重原子法解出,经全矩阵最小二乘修正,R=0.050,Rw=0.056.簇阴离子结构属M1型三核钼簇构型,Mo-Mo键2.577A;Mo-O-μ3键1.982A.还讨论了桥原子、键级以及配体对Mo-Mo键的影响。     

CRYSTAL STRUCTURE OF Mo_3(μ_3-O) (μ-S_2)_ 3 [S_2P(OEt)_2]_3I

<正> Mr=1178.9, monoclinic, P21/n, a=16.570(2), b=12.370(1), c=20.007(2) A,β=99.97(1)°, V=4039.0A3, Z=4, Dx=1.938 Mgm-3, λ(MoKα)=0.7107A, μ(MoKα)=23.96 F(000)=2296, room temperature. Final R value=0.047 for 4387 unique observed reflections. It consists of neutral mono-oxo-capped trinuclear molybdenum cluster molecules with an average Mo-Mo bond length of 2.626(4)A and an average Mo-0 bond length of 2.036(2)8.     

SYNTHESIS AND CRYSTAL STRUCTURE OF COMPLEX [CrMo_3 (μ_3-O)_3(μ-O)(μ-O_2CCH_3)_5(O_2CCH_3)_3]Na2 · H_2O

<正> The title complex C CrMo3 (μ3-O )3 (μ-O) (μ-O2CCH3 )5 (O2CCH3)3]2Na2 · H2O (Mr=1814. 32) crystallizes in monoclinic, space group P21/ n with a=11.209(5), b=18. 05(1), c=14. 44(1) A , β= 98. 30(5)°. V=2890 (3) A3, Z=2, A = 2. 08 g/cm3, F(000) -1780, Final R = 0. 049, Rw = 0. 058 for 2622 independent reflectons with I>3σ(I). The complex anion contains two Mo3O4 cores which connect two chromium atoms through four μ3-O atoms and eight bridging CH3COO- groups. Each of the Cr atoms and the Mo atoms is coordinated by six oxygen atoms. The anions are linked by Na cations to form one-dimensional infinite chain structure.     

The synthesis and crystal structure of novel Mo-Sn tetranuclear cubane-like cluster [Mo3(SnBr3)(μ3-O)(μ3-S)3(dtp)3(py)3]·(CH2Cl2)

The synthesis and crystal structure of the first example for hybrid Sn-Mo tetranuclear cubane-like cluster compound containing S/O mixed triple capping atom [Mo₃(SnBr₃)(μ ₃-O)(μ ₃-S)₃(dtp)₃(py)₃]·(CH₂Cl₂) (A) (dtp=S₂P(OC₂H₅)₂) are reported. The compound is prepared by the reaction of [Mo₃(μ ₃-O)(μ-S)₃(dtp)₄·(H₂O)] with SnBr ₃ ^? . The molecular structure of the cluster can be described as a [Mo₃OS₃] core with the SnBr ₃ ^? fragment linked to {Mo₃} triangle by three (μ ₃-S). Three Mo-Mo bond lengths are 2.616(2), 2.620(2), 2.628(2) Å, respectively, and the molecule has approximately C_3v symmetry. There is no bonding between Sn and Mo atoms, however, the addition of SnBr ₃ ^? may cause electron transfer from Sn²⁺ to [Mo₃OS₃] core to result in the shortening of Mo-Mo bond distances. The compound crystallizes in the monoclinic space group P2₁/n with refined lattice parameters ofa=13.012(4),b=22.877(6),c=18.585(6) Å,β=96.34(3)°,V=5498(3)ų, andZ=4. Full matrix refinement converged with final agreement factor ofR=0.054,R _w=0.064.     

Synthesis and Structure of Acetonitrile Solvates of Copper(II) Monofluoroacetate and Silver(I) Trifluoroacetate, [Cu2(CH2FCOO)4· 2CH3CN](CH3CN) and Ag3(CF3COO)3(CH3CN)2

Compounds [Cu₂(CH₂FCOO)₄· 2CH₃CN](CH₃CN) (I) and Ag₃(CF₃COO)₃(CH₃CN)₂(II) were synthesized and studied by X-ray structural analysis. Crystals Iare monoclinic, space group C2/c, a= 27.854(6), b= 8.286(2), c= 19.428(4) Å, = 106.82(3)°, V= 4292(2) ų, Z= 8, R ₁= 0.0426; crystals IIare triclinic, space group , a= 8.676(2), b= 9.819(2), c= 11.961(2) Å, = 95.27(3), = 109.59(3)°, = 104.60(3)°, V= 911.4(3) ų, Z= 2, R ₁= 0.0252. Structure Iis composed of the structural units (lanterns) typical of copper(II) carboxylates. The presence of an additional acetonitrile molecule noncoordinated by the copper atoms makes it possible to consider compound Ias a lattice clathrate. Structure IIhas no analogs among the silver carboxylates. It simultaneously contains silver atoms with coordination numbers varying from 2 to 4.     

Crystal Structures of 1,3-Calix[4]-bis-crown-6·3CH3CN and 1,3-Calix[4]-bis-(benzo-crown-6)·3 CH3CN

The crystal structures of a new solvate of the ditopic receptor 1,3-calix[4]-bis-crown-6, Bis-C6, and of 1,3-calix[4]-bis-(benzo-crown-6), Bis-benzoC6, are reported. Bis-C6.3 CH3CN (1) crystallizes in the monoclinic space group P21/n, a = 14.388(3), b = 26.947(8), c = 14.707(4) Å, = 113.19(3)°, V = 5241(5) Å3, Z = 4. Refinement led to a final conventional R value of 0.092 for 2723 reflections. The structure of (1) differs from the previously reported structure of Bis-C6.4 CH3CN by the conformation of one crown either chain. Two acetonitrile molecules are in the close neighbourhood of the crown ether cavities. Bis-benzoC6.3 CH3CN (2) crystallizes in the monoclinic space group P21/c, a = 10.391(4), b = 17.264(11), c = 30.426(9) Å, = 94.62(3)°, V = 5440(7) Å3, Z = 4. Refinement led to a final conventional R value of 0.106 for 2965 reflections. Two acetonitrile molecules are located near the crown ether cavities, as in (1). One of the crown ether conformations is the same as in the binuclear caesium complex of Bis-benzoC6, supporting the hypothesis of a preorganization of this ligand towards the complexation of this ion; the second crown ether chain is partially disordered.     

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.     

[C5H4C(CH3)(C3H7)CH2CH=CH2]NdMg2(μ3-OH)(μ3-Cl)(μ2-Cl)3(THF)4Cl的合成和晶体结构分析

用Ｘ－射线衍射法测定了［Ｃ５Ｈ４Ｃ（ＣＨ３）（Ｃ３Ｈ７）ＣＨ２ＣＨ＝ ＣＨ２］ＮｄＭｇ２（μ３－ＯＨ）（μ３－Ｃｌ）（μ２－Ｃｌ）３（ＴＨＦ）４Ｃｌ的晶体结构。它属三斜晶系,空间群为Ｐ１－ ,ａ＝ １２．６９８（３）, ｂ＝ １３．６１６（３）, ｃ＝ １３．７１２（３）, α＝ ６８．９１（３）, β＝ ８４．３４（３）, γ＝ ６３．０７（３）°, Ｖ＝ １９６６（１）３, Ｍｒ＝ ８４９．７４, Ｄｘ＝ １．４１２ ｇ·ｃｍ － ３, μ＝ １．７２９７ ｍ ｍ － １, Ｆ（０００）＝ ８４０, Ｚ＝ ２, Ｒ＝ ０．０７３, ｗ Ｒ＝ ０．０８６（Ｉ≥３σ（Ｉ））。分子中Ｎｄ（Ⅲ）原子的配位数为八,形成一个严重扭曲的八面体结构。两个Ｍｇ 原子的配位情况相似,它们的配位数都是六,构成两个扭曲的八面体。这三个八面体通过三个共用平面联接     

A ‘preformed chelate approach’ model for coupling amine-modified rhenium and technetium ‘3+1’ mixed ligand complexes to carboxylate residues: Crystal structure of ReO[CH3SCH2CH2N(CH2CH2S)2][p-SC6H4NH2] and ReO[CH3SCH2CH2N(CH2CH2S)2][p-SC6H4NHCOC6H5]

Selected ‘3+1’ mixed ligand oxorhenium and oxotechnetium complexes containing the SNS/S donor atom set have been modified by introduction of a bifunctional amine anchor on the p-position of the thiophenolato monodentate ligand. A representative series of complexes containing several tridentate ligands was prepared both at macromolar (Re complexes) and nanomolar (^99mTc complexes) amounts. Coupling of these complexes to activated carboxylate groups was performed according to the ‘preformed chelate approach’ using benzoyl chloride as a model molecule. Coupling yields were high both at nanomolar and millimolar metal concentration, as revealed by high-performance liquid chromatographic analysis of ^99mTc and Re species adopting parallel radiometric and photometric detection modes. All Re compounds have been characterized by classical analytical methods. In addition, the structures of representative parent ReO[CH₃SCH₂CH₂N(CH₂CH₂S)₂][p-SC₆H₄NH₂] and daughter ReO[CH₃SCH₂CH₂N(CH₂CH₂S)₂][p-SC₆H₄NHCOC₆H₅] complexes were solved by X-ray crystallography. Both compounds adopt a distorted trigonal bipyramidal geometry around rhenium, wherein the oxo group and the sulfur atoms of the SNS ligand occupy the equatorial plane and the nitrogen atom and the sulfur of the monothiol are located at the apical positions trans to each other.