F2 Σ+ -X 2Σ +Band System of Cobalt Carbide

The laser-induced fluorescence excitation spectrum of CoC was recorded in the spectral region from 13500 cm-1 to 22000 cm-1, in which the CoC molecules were produced by the reaction of sputtered cobalt atoms with methanol under supersonic jet cooled conditions. Much of the visible spectrum was assigned to transitions between the X2∑+ ground state and F2∑+ state. The 11 bands assigned as (v’=3-13, 0) transitions of the F2∑+- X2∑+ band system were observed and rotationally analyzed. Equilibrium constants for the F2∑+ state were Te=1362 cm-1, ωe=669 cm-1 ,ωe?e=4.3 cm-1, Be=0.546 cm-1, and Re=1.758A. Some new bands were observed.     

Unusual ion UO4? formed upon collision induced dissociation of [UO2(NO3)3]?, [UO2(ClO4)3]?, [UO2(CH3COO)3]? ions

The following ions [UO₂(NO₃)₃]⁻, [UO₂(ClO₄)₃]⁻, [UO₂(CH₃COO)₃]⁻ were generated from respective salts (UO₂(NO₃)₂, UO₂(ClO₄)₃, UO₂(CH3COO)2) by laser desorption/ionization (LDI). Collision induced dissociation of the ions has led, among others, to the formation of UO₄ ⁻ ion (m/z 302). The undertaken quantum mechanical calculations showed this ion is most likely to possess square planar geometry as suggested by MP2 results or strongly deformed geometry in between tetrahedral and square planar as indicated by DFT results. Interestingly, geometrical parameters and analysis of electron density suggest it is an U^VI compound, in which oxygen atoms bear unpaired electron and negative charge.     

Synthesis and structure of the platinum complexes [Bu4N]+[PtBr5(DMSO)]?, [Ph4P]+[PtBr5(DMSO)]?, and [Ph3(n-Am)P]+[PtBr5(DMSO)]?

The complexes [Bu₄N]₂⁺[PtBr₆]²⁻ (I), [Ph₄P]₂⁺[PtBr₆]²⁻ (II), and [Ph₃(n-Am)P]₂⁺ (III) are synthesized by the reactions of tetrabutylammonium bromide, tetraphenylphosphonium bromide, and triphenyl(n-amyl)-tetraphenylphosphonium bromide, respectively, with potassium hexabromoplatinate (mole ratio 2: 1). After recrystallization from dimethyl sulfoxide, complexes I, II, and III transform into [Bu₄N]⁺[PtBr₅(DMSO)]⁻ (IV), [Ph₄P]⁺[PtBr₅(DMSO)]⁻ (V), and [Ph₃(n-Am)P]⁺[PtBr₅(DMSO)]⁻ (VI). According to the X-ray diffraction data, the cations of complexes IV–VI have a slightly distorted tetrahedral structure. The N-C and P-C bond lengths are 1.492(7)–1.533(6) and 1.782(10)–1.805(10) ?, respectively. The platinum atoms in the mononuclear anions are hexacoordinated. The dimethyl sulfoxide ligands are coordinated with the Pt atom through the sulfur atom (Pt-S 2.3280(18)–2.3389(11) ?). The Pt-Br bond lengths are 2.4330(6)–2.4724(6) ?.     

1,2,3,4,7-Pentamethylindenyl complex [(η5-C9H2Me5)RhI2]2 as a synthon for the [(η5-C9H2Me5)Rh]2+ fragment

The reaction of the iodide complex [(η⁵-C₉H₂Me₅)RhI₂]₂ (1) or the acetonitrile complex [(η⁵-C₉H₂Me₅)Rh(MeCN)₃]²⁺ with Tl[Tl(η-7,8-C₂B₉H₁₁)] afforded rhodacarborane (η⁵-C₉H₂Me₅)Rh(7,8-C₂B₉H₁₁) (2). The cationic triple-decker complex with the bridging boratabenzene ligand [Cp*Fe(μ-η:η-C₅H₃Me₂BMe)Rh(η⁵-C₉H₂Me₅)]²⁺ (3) was synthesized by the reaction of the nitromethane solvate [(η⁵-C₉H₂Me₅)Rh(MeNO₂)₃]²⁺ with the sandwich compound Cp*Fe(η-C₅H₃Me₂BMe). The structure of 2 was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1623–1625, August, 2008.     

[Pt2(P2O4H2)4]4-和[Pt2(P2O4CH4)4]4-基态和激发态性质的理论研究

采用从头计算MP2和CIS方法分别优化等电子双核d⁸配合物[Pt₂(P₂O₄H₂)₄]^4-和[Pt₂(P₂O₄CH₄)₄]^4-的基态和激发态结构。结果表明基态Pt-Pt距离分别为0.290 5和0.298 7 nm，与实验的0.292 5和0.298 0 nm符合。NBO计算的Pt-Pt键级以及Pt原子间伸缩振动说明Pt-Pt相互作用具有吸引本质。CIS计算揭示电子激发到Pt-Pt的σ(p_z)成键轨道使得相互作用增强。保持激发态几何，含时密度泛函理论(TD-DFT)计算的溶液发射分别为449和475 nm，与实验值512和510 nm接近。     

Radiometrische Titrationen mit [60Co(CN)6]3?-Ionen

Ohne Zusammenfassung     

X-ray and conformation analysis of the new trinuclear cluster of osmium Os3(μ,η2-OCC6H5)(η3-C3H5)(CO)9

The crystal structure of the Os₃(μ,η²-O=CC₆H₅)(η³-C₃H₅)(CO)₉ cluster synthesized by the reaction of the (μ-H)Os₃(μ-O=CC₆H₅)(CO)₁₀ complex with allylamine in chloroform was determined by X-ray analysis. Prolonged storage of the reaction mixture led to N-C bond cleavage in allylamine and η³-addition of the allyl fragment at one of the Os atoms (Os-C 2.246 ?, 2.248 ?, and 2.273 ?). The unit cell parameters of the complex are a = 9.494(1) ?, b = 10.479(1) ?, c = 12.474(2) ?, α = 84.55(1)°, β = 70.08(1)°, γ = 70.72(1)°, V = 1255.8(4), ?³, space group P , Z = 2; C₁₉H₁₀O₁₀Os₃; d _calc = 2.922 g/cm³, 3085 I _hkl > 2σ _I of 3611 collected reflections; R = 0.0252. The structure of Os₃(μ,η²-O=CC₆H₅)(η³-C₃H₅)(CO)₉ is molecular. The plane of the Os₃ triangle and the OsCOOs plane are connected according to the “butterfly” principle with an angle of 103.4° between them. The Os-Os distances in the cluster core vary from 2.836(1) ? to 2.844(1) ?; the Os-C_carb distances are 1.88(1)–1.97(1) ?; the distances to the atoms of the bridging ligands are Os-C 2.11(1) ?, Os-O 2.14(1) ?; the O-C bridging bond is 1.24(1) ?. of the Os₃(μ,η²-O=CC₆H₅)(η³-C₃H₅)(CO)₉ triosmium cluster were studied theoretically. The potential curve of the internal rotation of the allyl ligand relative to the Os(1)-C(9) bond was determined. The rotation barrier of the allyl ligand in crystal relative to the Os(1)-C(9) bond is 8.38 kJ/mol, and the rotation of the ligand is not hindered. The effects of the intra-and intermolecular interactions on the conformation state of the cluster complex are considered. Original Russian Text Copyright ? 2008 by V. A. Maksakov, N. V. Pervukhina, N. V. Podberezskaya, M. Yu. Afonin, V. A. Potemkin, and V. P. Kirin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 5, pp. 926–932, September–October, 2008.     

High Precision Cavity Ring Down Spectroscopy of 6υ3 Overtone Band of 14N2 16O near 775 nm

Transitions of the 6υ₃ overtone band of ¹⁴N₂ ¹⁶O near 775 nm have been studied by continuous-wave cavity ring-down spectroscopy. Line positions and intensities were derived from a fit of the line shape using a hard-collisional profile. The line positions determined with absolute accuracy of 5×10^-4 cm^-1 allowed us to reveal finer ro-vibrational couplings taking place after J>14 except a strong anharmonic interaction identified by the effective Hamiltonian model. The absolute line intensities have also been retrieved with an estimated accuracy of 2% for a majority of the unblended lines. A new set of ro-vibrational and dipole moment parameters were derived from the experimental values. A comparison between the line positions and intensities of the 6υ₃ band obtained in this work and those from previous studies is given.     

Separation of Yb as YbSO4 from the 176Yb target for production of 177Lu via the 176Yb(n, γ)177Yb→177Lu process

An effective and simple process for the separation of ¹⁷⁷Lu from neutron-irradiated Yb targets was developed. Irradiated Yb target was dissolved in H₂SO₄ solution and after reduction with sodium amalgam Yb was precipitated in the form of YbSO₄. From 50 mg of Yb irradiated target only 1 mg Yb remains in solution after precipitation and separation of YbSO₄. The overall recovery of ¹⁷⁷Lu is estimated at 73%. Further efficient chromatographic separation of carrier-free ¹⁷⁷Lu from 1 mg of Yb is relatively easy and is described in several papers.     

Regioselectivity of the addition of ?CCl3 and ?But radicals to (η2-C70)[Os(CO)(PPh3)2(CNBut)]n (n = 1, 2): an ESR study

The addition of ^•CCl₃ and ^•Bu^t radicals to (η²-C₇₀)Os(CO)(PPh₃)₂(CNBu^t) (1) and (η²-C₇₀)[Os(CO)(PPh₃)₂(CNBu^t)]₂ (3) was studied by ESR spectroscopy. The metal fragment in complex 1 does not influence the regioselectivity of the addition of the radicals to it. The stability of the spin adducts formed upon addition of free radicals to complexes 1 and 3 is mainly governed by delocalization of the unpaired electron over three hexagonal rings.     

~1H和~(19)F NMR研究镍系催化丁二烯聚合中醇类对BF_3·OEt_2的增溶作用

<正> 在镍系催化丁二烯聚合中,助催化剂BF_3·OEt_2在加氢汽油中溶解性差,往往形成非均相体系,因而降低了催化剂体系的稳定性和氟的利用率。我们曾研究了A1(i-Bu)_3分别与丙醇、丁醇、戊醇,己醇、辛醇、壬醇、癸醇和十六醇按等摩尔交换,制得A1(i-Bu)_2OR作助催化剂,观察Al/B与催化活性的关系,发现以十六醇为最好,Al/B在0.25—0.95聚合活性较高,超出此限活性迅速下降。为了进一步提高Al/B,采用了向镍催化体系添加醇的方法。聚合实验证实了该法可提高氟的利用率。测定醇-硼体系的~1HNMR,证实了醇-硼分子间形成了氟-氢氢键。     

Controlled/living cationic polymerization of styrene with BF3OEt2 as a coinitiator in the presence of water: Improvements and limitations

The controlled/living cationic polymerization of styrene using R-OH/BF₃OEt₂ (R-OH = 1-phenylethanol (1), 2-phenyl-2-propanol (2) and 1-(4-methoxyphenyl)ethanol (3)) at 0 °C in CH₂Cl₂ and in the presence of water was investigated. With 1/BF₃OEt₂, the poor control over molecular weight and molecular weight distribution was ascribed to a competitive protonic initiation induced by water. The molecular weight of the polymers obtained with 2/BF₃OEt₂ and 3/BF₃OEt₂ at low water content ([H₂O] ? 0.11 M) increased in direct proportion to the monomer conversion in agreement with the calculated values, assuming that one initiator molecule generates one polymer chain, but the molecular weight distribution was found relatively broad (M_w/M_n ∼ 1.8). ¹H NMR analyses confirmed that polymerization proceeds via reversible activation of C-OH terminus, but some loss of hydroxyl functionality was revealed. Some trials using high water contents in the recipe ([H₂O] ? 1.6 M) produced only traces of polymer due to catalyst decomposition.     

THE MECHANISM OF THE COPOLYMERIZATION OF BF_3-COMPLEXED ETHYL ACRYLATE WITH PROPYLENE

The copolymerization of BF_2-omplexed ethyl acrylate with propylene in the presence ofAIBN at 25℃was investigated. It was found that the rate of the copolymerization was propor-tional to the square root of the initiator concentration. The chain transfer agent CCl_4 greatly af-fects the inherent viscosity of the resulting copolymer. The smaller the dielectric constant of thesolvent, the greater the rate of copolymerization is. The equal concentration of the two monomersgive the maximum copolymerization rate. The ~1H-NMR and ~(13)C-NMR analysis indicated, when[EA.BF_2]/[EA.BF_2]+[P]>0.5, the resulting copolymer was the acrylate-rich random copoly-mer. Through the kinetic experiments we suggest that copolymerization follows the mechanismof the random copolymerization of the ternary complex with binary complex. When [EA.BF_3]/[EA.BF_2]+[P]<0.5, the resulting copolymer is always strictly alternating, and the alternatingcopolymerization follows the mechanism of the ternary complex homopolymerization. Usingthe homolog of the propylene, 1-pentene, we found that BF_3-complexed ethyl acrylate can forma ternary complex with 1-pentene identified by UV spectroscopy. This is a strong evidence forthe mechanism of ternary complex homopolymerizetion.     

Chiral discrimination in the reactions of the enolate E-[(η5-C5H5)Fe(CO)(PPh3)COCHMe]−Li+ with cis and trans but-2-ene oxides in the presence of BF3·OEt3

$\text{cis}$ and $\text{trans}$-but-2-ene oxides undergo S_N2 opening with the lithium enolate derived from [(η⁵-C₅H₅)Fe(CO)(PPh₃)COCH₂CH₃] in the presence of BF₃·OEt₂; preferential opening occurs where the enolate configuration at iron matches that of the epoxide carbon being attacked.     

Ruthenium Catalyzed C−H Acylmethylation of N‐Arylphthalazine‐1,4‐diones with α‐Carbonyl Sulfoxonium Ylides: Highway to Diversely Functionalized Phthalazino‐fused Cinnolines

A direct ortho‐Csp²‐H acylmethylation of 2‐aryl‐2,3‐dihydrophthalazine‐1,4‐diones with α‐carbonyl sulfoxonium ylides is achieved through a Ru^II‐catalyzed C?H bond activation process. The protocol featured high functional group tolerance on the two substrates, including aryl‐, heteroaryl‐, and alkyl‐substituted α‐carbonyl sulfoxonium ylides. Thereafter, 2‐(ortho‐acylmethylaryl)‐2,3‐dihydrophthalazine‐1,4‐diones were used as potential starting materials for the expeditious synthesis of 6‐arylphthalazino[2,3‐a]cinnoline‐8,13‐diones and 5‐acyl‐5,6‐dihydrophthalazino[2,3‐a]cinnoline‐8,13‐diones under Lawesson's reagent and BF₃?OEt₂ mediated conditions, respectively. Of these, the BF₃?OEt₂‐mediated cyclization proceeded in DMSO as a solvent and a methylene source via dual C?C and C?N bond formations.     

1,4-Dihydropyridine/BF3OEt2 for the reduction of imines: Influences of the amount of added BF3OEt2 and the substitution at N-1 and C-4 of the dihydropyridine ring

We have evaluated four 1,4-dihydropyridines (DHPs 1a, 1b, 1c and 1d) as reducing agents, which presented free (hydrogenated) or phenyl-substituted N-1 and C-4 positions of the DHP ring. Reactions combining each of the DHP and different amounts of BF₃OEt₂ were evaluated for the reduction of imine 2a (N-benzylideneaniline). DHP simultaneously substituted at N-1 and C-4 (1a), and DHP substituted at C-4 (1b) gave lower yields for reduction of 2a in comparison with DHPs 1c and 1d (both unsubstituted at the C-4 position). By evaluating the amount of added BF₃OEt₂ to the reaction mixture, we have found that DHP 1c (substituted at N-1) provided its best yield for amine 3a (82%) when associated with stoichiometric amounts BF₃OEt₂, while DHP 1d (N-1- and C-4-unsubstituted derivative) was more effective (90% yield) with catalytic quantities of the Lewis acid. The reaction system using DHP 1c under stoichiometric BF₃OEt₂ could also be successfully applied with additional imine examples and under reductive amination conditions.     

Controlled Formation of Thiol‐Thiolate Hydrogen versus Disulfide Bonds between Two Iridium(III) Centers

Here, we report an iridium(III) coordination system with 2‐aminoethanethiolate (aet), which shows the formation of S?H???S hydrogen and S?S disulfide bonds in a controlled manner. Treatment of fac‐[Ir(aet)₃] with aqueous HBF₄ under aerobic conditions gave dinuclear [Ir₂(aet)₄(cysta)]²⁺ ([ 1 ]²⁺; cysta=cystamine) with a single S?S disulfide bond, while dimeric [Ir₂(aet)₃(Haet)₃](BF₄)₃ ([ 2 ](BF₄)₃) with a triple S?H???S hydrogen bond was formed by similar treatment under anaerobic conditions. Upon exposure to air, [ 2 ]³⁺ was converted to dinuclear [Ir₂(aet)₂(Haet)₂(cysta)]⁴⁺ ([ 3 ]⁴⁺), in which two Ir^III centers are spanned by a double S?H???S hydrogen bond and a single S?S disulfide bond. Complex [ 3 ]⁴⁺ was interconvertible with [ 1 ]²⁺ via the removal/addition of protons on S donors, accompanied by the intermolecular exchange of the fac‐[Ir(aet)₃] units. Complexes [ 1 ]²⁺, [ 2 ]³⁺, and [ 3 ]⁴⁺, isolated as BF₄^? salts, were fully characterized by single‐crystal X‐ray crystallography.     

The molecular structure of a three-coordinate palladium(II)-styrene complex [Pd(η5-C5H5)(PEt3)(styrene)]BF4

The molecular structure of a three-coordinate palladium(II)-styrene complex, [Pd(η⁵-C₅H₅)(PEt₃)(styrene)]BF₄ has been determined by means of X-ray diffraction. The crystal belongs to the monoclinic system, space group P2₁/c, with four formula units in a cell of dimensions: a 10.229(3), b 11.262(3), c 18.760(5) Å and β 103.77(2)°. The structure was solved by the heavy atom method, and refined by the least-squares procedure to R = 0.050 for 3635 observed reflections. The palladium atom is surrounded by the cyclopentadienyl group, the triethylphosphine ligand and the olefinic bond of styrene in the cationic complex. In the palladiumstyrene bonding, the olefinic bond is inclined by 77.3° to the coordination plane defined by the Pd and P atoms and the center of the cyclopentadienyl ring (PdC(1) 2.176(6), PdC(2) 2.234(5) and C(1)C(2) 1.369(8) Å).     

Synthesis of 1,1′-di-t-butylstannocene and its reaction with trifluoroborane. The crystal and molecular structure of η5-(CH3)3CC5H4Sn+BF4−

The reaction of Li(CH₃)₃CC₅H₄ with SnCl₂ in THF affords 1,1′-di-t-butylstannocene in 78% yield as an air-sensitive oil. ¹H and ¹³C NMR spectra are consistent with a pentahapto-structure. Mössbauer parameters of the stannocene and its trimethylsilyl counterpart match closely those of known stannocenes and neither compound appears to undergo oligomerization. The reaction of 1,1′-di-t-butylstannocene with BF₃ in CH₂Cl₂ affords η⁵-(CH₃)₃CC₅H₄Sn⁺ BF₄^? and other uncharacterized product(s) thought to involve tetracoordinate tin. The structure of η⁵-(CH₃)₃CC₅H₄Sn⁺ BF₄^? was determined by single crystal X-ray diffraction (orthorhombic,Pbcn, (T 25°C), a 18.423(3), b 11.723(1), c 11.044(2) Å, Z Å, m.p. 95–96°C, colorless, Mo-K_α, R = 0.043).     

Formation and stabilization of monovalent nickel in the Ni(COD)2/BF3 · OEt2 catalytic system

The catalytic system Ni(COD)₂/BF₃ · OEt₂ was used to demonstrate the possibility of stabilizing Ni⁺ ions in toluene solutions without traditional organoelement ligands.