Vibrational spectrum of [(CD3)3S]I and normal coordinate calculations for [(CH3)3S] and [(CD3)3S] cations

IR (4000-30 cm⁻¹) and Raman (4000-0 cm⁻) spectra of [(CD₃)₃S]I have been observed, together with those of [(CH₃)₃S]I. By assuming a C_3v molecular symmetry for the cations [(CH₃)₃S]⁺ and [(CD₃)₃S]⁺, all the active fundamentals of [(CD₃)₃s]⁺ have been assigned and normal coordinate calculations have been carried out by a symmetry force field for [(CH₃)₃S]⁺ and [(CD₃)₃S]⁺. The strength of the S---C and C---H bonds in the compound has been compared with that in dimethyl sulfide by using their valence stretching force constants.     

Preparation of some complexes of the type (C6H5)3P[(CH3)2AsCH2CH(R)CH2As(CH3)2] M(CO)3 (M = Mo or W,R = H or C(CH3)3)

The title compounds, which contain six-membered chelate rings locked in the chair conformation, have been prepared by the reaction of (C₆H₅)₃P with the appropriate tetracarbonyl derivative in refluxing mesitylene.     

Syntheses and structural studies on two cycloruthenapentadienyl complexes: [(CO)3RuC4(CH2OH)4]Ru(CO)3·H2O and [(CO)3RuC4(CH2CH2OH)2(C2H5)2]Ru(CO)3

Syntheses and single-crystal X-ray diffraction studies have been completed on two cycloruthenapentadienyl (CO)₆Ru₂L₂ derivatives, with L = CH₂OHC = CCH₂OH and C₂H₅C=CCH₂CH₂OH respectively. Crystal data are as follows: for [(CO)₃RuC₄(CH₂OH)₄]Ru(CO)₃·H₂O, P2₁/c, a 13.72(1), b 9.501(4), c 14.86(1) Å, β 101.10(6)°, R_w = 0.052 for 1911 reflections; for [(CO)₃RuC₄(CH₂CH₂OH)₂(C₂H₅)₂]Ru(CO)₃, P2₁/c, a 9.191(3), b 16.732(4), c 14.903(3) Å, β 113.61(4)°, R_w = 0.042 for 2865 reflections. Both compounds are built up from binuclear units, each unit being regarded as a Ru(CO)₃ fragment π-bonded to a cycloruthenapentadienyl ring. The molecular parameters are compared with those of known cyclometallapentadienyl complexes of transition metals. The presence of a semi-bridging CO group is discussed.     

Photochemically induced insertion of alkynes into the metal-metal bond of [FeX(CO)3]2 complexes (X = SCH3, SC6H5, P(CH3)2)

It is shown that alkynes, such as CF₃C≡CCF₃ and CH₃OOCC≡CCOOCH₃, which contain strongly electron-attracting groups, undergo insertion into the metal-metal bond of [FeX(CO)₃]₂ complexes (X = SCH₃, SC₆H₅, P(CH₃)₂) under UV irradiation. The reactions of the products with trimethylphosphine are also described.     

Preparation and structural characterization of [RuCl2(CO)2{Te(CH2SiMe3)2}2] and [RuCl2(CO){Te(CH2SiMe3)2}3]

The objective of the present work was to synthesize mononuclear ruthenium complex [RuCl₂(CO)₂{Te(CH₂SiMe₃)₂}₂] (1) by the reaction of Te(CH₂SiMe₃)₂ and [RuCl₂(CO)₃]₂. However, the stoichiometric reaction affords a mixture of 1 and [RuCl₂(CO){Te(CH₂SiMe₃)₂}₃] (2). The X-ray structures show the formation of the cis(Cl), cis(C), trans(Te) isomer of 1 and the cis(Cl), mer(Te) isomer of 2. The ¹²⁵Te NMR spectra of the complexes are reported. The complex distribution depends on the initial molar ratio of the reactants. With an excess of [RuCl₂(CO)₃]₂ only 1 is formed. In addition to the stoichiometric reaction, a mixture of 1 and 2 is observed even when using an excess of Te(CH₂SiMe₃)₂. Complex 1 is, however, always the main product. In these cases the ¹²⁵Te NMR spectra of the reaction solution also indicates the presence of unreacted ligand.     

Germylene complexes of tungsten pentacarbonyls W(CO)5GeCl2 and W(CO)5GeW(CO)5: Electrochemical synthesis and quantum-chemical computations

Convenient synthetic route to prepare the germylene complexes of tungsten pentacarbonyls, W(CO)₅GeCl₂ and W(CO)₅GeW(CO)₅, electrochemically is developed. Combined quantum-chemical/IR spectroscopic approach is used for identification of the synthesized compounds. Good agreement between theoretical and experimental spectra can be regarded as one of the proofs of their supposed structures.     

Dual luminescences in [W(Cp)(CO)3]2 and [Mo(Cp)(CO)3]2

Cyclohexane solutions of [W(Cp)(CO)₃]₂ and [Mo(Cp)(CO)₃]₂ exhibit weak bimodal emission spectra when excited With 354 nm picosecond pulses, but do not luminesce when pumped at 530 nm. Picosecond lifetimes characterize the short-wavelength, emission bands, which may originate from metal-cyclopentadienyl CT excited states.     

FeCo2(CO)7(μ3-S)(O[P(SCH2)2]2)的合成与晶体结构

许多化学工作者对单齿膦配体（ＰＰｈ３,ＰＢｕｎ３,ＰＥｔ２Ｐｈ,Ｐ（ＯＥｔ）３,Ｐ（ＯＣ６Ｈ５）３）与母体簇合物ＦｅＣｏ２（ＣＯ）９（μ３－Ｓ）的取代反应进行过详细研究［１－３］,但对双齿膦配体与母体簇合物的取代反应研究报导较少．Ａｉｍｅ［４］合成了含双齿膦配体的簇合物ＦｅＣｏ２（ＣＯ）７（μ３－Ｓ）（Ｐｈ２ＰＣＨ２ＰＰｈ２）,并用１３ＣＮＭＲ和ＩＲ光谱方法对其结构进行了表征．到目前为止,含双齿膦配体的该类簇合物的晶体与分子结构还未见报导．ＲｏｓａｎｎａＲｏｓｓｅｔｔｉ［２］通过研究母体簇合物与…     

Actinide-centered cyclometalation chemistry. An unusually distorted thorium bishydrocarbyl: Thp[η5-(CH3)5C5]2CH2Si(CH3)3]2

The crystal and molecular structure of the complex Th[η⁵-(CH₃)₅C₅]₂[CH₂-Si(CH₃)₃]₂, which undergoes facile intramolecular cyclometalation to the thoracyclobutane Th[η⁵-(CH₃)₅C₅]₂(CH₂)₂Si(CH₃)₂, is reported. While the Th[η⁵-(CH₃)₅C₅]₂ ligation is unexceptional, the Th[CH₂Si(CH₃)₃]₂ fragment is highly unsymmetrical having Th-C (corresponding angle Th-C-Si) 2.51(1) Å (132.0(6)°) and 2.46(1) Å (148.0(7)°). This conformation, which appears to result from severe intramolecular non-bonded contacts, allows a methyl hydrogen atom of one CH₂Si(CH₃)₃ ligand to approach within ca. 2.3 Å of the α-carbon atom of the other CH₂Si(CH₃)₃ ligand.     

Vibrational spectra of [(CH3)3NH]3Sb2Cl9, [(CH3)3NH]3Bi2Cl9 and their mixed crystals

The IR and Raman spectra of [(CH₃)₃NH]₃Sb₂Cl₉ (A), [(CH₃)₃NH]₃Bi₂Cl₉ (B) and two of their mixed crystals containing respectively 33% (AB.33) and 42% Bi (AB.42) are analyzed and compared. A and AB.33 show ferroelectric–paraelectric phase transition at 364 K and 344 K, respectively. AB.42 and B are paraelectric in the temperature range between 90 and 365 K. Most of the vibrational modes show continuous changes, with the temperature, in the IR frequencies or intensities with no soft mode behavior. However, characteristic ν(NHCl) and δ(NHCl) vibrations of weakly hydrogen-bonded species are only observed in A and AB.33 below the temperature of the phase transition and are related to the ferroelectricity. The evolution of the IR spectra with the temperature suggests that the ferroelectric properties are connected with the reorientation of the cations which needs a breaking of the weak NHCl hydrogen bonds in the paraelectric phase.     

Geometries and properties of bimetallic phosphido-bridged complex Cp(CO)2W(μ-PPh2)W(CO)5 and Cp(CO)3W(μ-PPh2)W(CO)5

Complete geometry optimizations were carried out by HF and DFT methods to study the molecular structure of binuclear transition-metal compounds (Cp(CO)₃W(μ-PPh₂)W(CO)₅) (I) and (Cp(CO)₂W(μ-PPh₂)W(CO)₅) (II). A comparison of the experimental data and calculated structural parameters demonstrates that the most accurate geometry parameters are predicted by the MPW1PW91/LANL2DZ among the three DFT methods. Topological properties of molecular charge distributions were analyzed with the theory of atoms in molecules. (3, −1) critical points, namely bond critical point, were found between the two tungsten atoms, and between W1 and C10 in complex II, which confirms the existence of the metal–metal bond and a semi-bridging CO between the two tungsten atoms. The result provided a theoretical guidance of detailed study on the binuclear phosphido-bridged complex containing transition metal–metal bond, which could be useful in the further study of the heterobimetallic phosphido-bridged complexes.     

Multiparameter equations of state for siloxanes: [(CH3)3-Si-O1/2]2-[O-Si-(CH3)2]i=1,…,3, and [O-Si-(CH3)2]6

This article presents the continuation of the work on the development of technical equations of state for linear and cyclic siloxanes already documented in this journal. The fluids considered herewith are octamethyltrisiloxane (MDM, C₈H₂₄Si₃O₂), decamethyltetrasiloxane (MD₂M, C₁₀H₃₀Si₄O₃), dodecamethylpentasiloxane (MD₃M, C₁₂H₃₆Si₅O₄), dodecamethylcyclohexasiloxane (D₆, C₁₂H₃₆Si₆O₆). The 12-parameter functional form proposed by Span and Wagner has been selected because of its positive characteristics. Siloxanes are produced in bulk quantities and are mostly utilized in the cosmetics industry and, mixed, as high-temperature heat transfer fluids. Furthermore, they are used as working fluids in high-temperature organic Rankine cycle power plants. The available property measurements are carefully evaluated and selected for the optimization of equation of state parameters. For some of the fluids, experimental values are scarce, therefore ad hoc estimation methods have been used to supply more information to the procedure for the optimization of the parameters of the equation of state. In addition, saturated liquid density and vapor pressure measurements are correlated with the equations proposed by Daubert and Wagner–Ambrose, respectively, to provide short, simple, and accurate equations for the computation of these properties. The recently developed isobaric ideal-gas heat capacity correlation for the selected siloxanes is included in the thermodynamic models. The performance of the newly developed equations of state is tested by comparison with experimental data and also with predictions calculated with the Peng–Robinson–Stryjek–Vera cubic EoS, as this model was adopted in previous technical studies. The new thermodynamic models perform significantly better than cubic equations of state. T–s and P  – v$v$ diagrams for all the substances are also reported.     

Activation of 1,3,5-trimethyl-1,3,5-triazacyclohexane by Os3(CO)12 to form amidino [(MeN)2CH] cluster complexes

Reaction of 1,3,5-trimethyl-1,3,5-triazacyclohexane [(MeNCH₂)₃] with Os₃(CO)₁₂ in refluxing toluene results in C-H and C-N bond activation of the (MeNCH₂)₃ ligand to afford three amidino cluster complexes (μ-H)Os₃(CO)₁₀[μ,η²-CH(NMe)₂] (1), (μ-H)Os₃(CO)₉[μ₃,η²-CH(NMe)₂] (2), and Os₂(CO)₆[μ,η²-CH(NMe)₂]₂ (3). The controlled experiments show that thermolysis of 1 yields 2, and heating 2 in the presence of (MeNCH₂)₃ ligand produces 3. The molecular structures of 1 and 3 have been determined by an X-ray diffraction study.     

The enthalpies of formation of CH3Mn(CO)5 and of CH3Re(CO)5, and the strengths of the CH3Mn and CH3Re bonds

From measurements of the heats of iodination of CH₃Mn(CO)₅ and CH₃Re(CO)₅ at elevated temperatures using the ‘drop’ microcalorimeter method, values were determined for the standard enthalpies of formation at 25° of the crystalline compounds: ΔH^o_f[CH₃Mn(CO)₅, c] = ?189.0 ± 2 kcal mol^?1 (?790.8 ± 8 kJ mol^?1), ΔH^o_f[Ch₃Re(CO)₅,c] = ?198.0 ± kcal mol^?1 (?828.4 ± 8 kJ mo^?1). In conjunction with available enthalpies of sublimation, and with literature values for the dissociation energies of MnMn and ReRe bonds in Mn₂(CO)₁₀ and Re₂(CO)₁₀, values are derived for the dissociation energies: D(CH₃Mn(CO)₅) = 27.9 ± 2.3 or 30.9 ± 2.3 kcal mol^?1 and D(CH₃Re(CO)₅) = 53.2 ± 2.5 kcal mol^?1. In general, irrespective of the value accepted for D(MM) in M₂(CO)₁₀, the present results require that, D(CH₃Mn) = $\text{1}\text{2}$D(MnMn) + 18.5 kcal mol^?1 and D(CH₃Re) = $\text{1}\text{2}$D(ReRe) + 30.8 kcal mol^?1.     

Internally coordinated organozinc-transition metal compounds. Crystal structure of (CH3)2N(CH2)3ZnW(ν-C5H5)(CO)3

The stabilities of simple and internally coordinated organozinc-transition metal compounds towards disproportionation have been investigated by the microwave titration technique. Simple alkyl- and aryl-derivatives disproportionate to such an extent as to preclude isolation. Internal coordination was found to stabilize the asymmetric compounds, and several derivatives containing the dimethylaminopropyl group were isolated. The crystal structure of one of them, Me₂N(CH₂)₃-ZnW(Cp)(CO)₃, was determined by a single-crystal X-ray study. The crystals are orthorhombic, space group P2₁2₁2₁, with four molecular units in a cell with parameters a 8.406(1), b 12.179(2) and c 16.642(2) Å. The structure was solved by standard Patterson and Fourier techniques. The refinement, with anisotropic temperature factors for the two heavy atoms, converged at R_F = 0.092 (R_wF = 0.089) for 1536 observed reflections with I>2.5σ(I). The molecule consists of a central tungsten atom, surrounded in a tetragonal pyramidal fashion by a cyclopentadienyl group in the apical position and three carbon monoxyde molecules and a zinc atom occupying the basal positions. The zinc atom is three-coordinate, being surrounded by the tungsten atom and the chelating dimethylaminopropyl group; there is, however, a short intermolecular contact between zinc and a carbonyl oxygen atom at 2.61(3) Å.     

Transition metal carbene chemistry 2: kinetic studies on the nucleophilic substitution reactions of (CO)5MC(SCH3)CH3 (M = Cr and W) with morpholine in aqueous acetonitrile

Kinetic studies of the aminolysis of [methyl(thiomethyl)carbene]pentacarbonyl chromium(0),(CO)₅CrC(CH₃)(SCH₃) (1-Cr(S)) and [methyl(thiomethyl)carbene]pentacarbonyltungsten(0), (CO)₅WC(CH₃)(SCH₃) (1-W(S)), with morpholine, a secondary amine, in 50% acetonitrile-50% H₂O (v/v at 25 °C) is reported. The second-order rate constant (k_A in m⁻¹ s⁻¹) increases with amine concentration, giving a linear dependence with an intercept on the rate axis and a tendency towards leveling off at higher amine concentration. The reaction was found to undergo general base catalysis. The mechanism proposed is very similar to those for ester reactions, involving a nucleophilic addition of amine to the substrate to yield a zwitterionic tetrahedral intermediate in the first step, followed by deprotonation to form in the second step, which, in the third step, converted to product by H₂O and/or conjugate acid of the base (BH⁺), assisted MeS⁻ expulsion. The reactivity (k₁) of 1-W(S) was found to be higher than that of 1-Cr(S), whereas, comparable , water catalyzed and , BH⁺ catalyzed, leaving group departure were found for both the carbenes complexes. All these observations have been explained successfully.     

Synthesis and reactivity of [(RRN)2PH]Fe(CO)4 complexes. X-ray crystal structure of [(Ph2N)2PH]Fe(CO)4

KHFe(CO)₄ reacts with tris(amino)phosphines by substitution at phosphorus leading to [bis(amino)phosphine]tetracarbonyliron complexes [(R¹R²N)₂PH]Fe(CO)₄. The X-ray structure has been determined for R¹=R²=Ph. Deprotonation of these complexes with KH affords stable potassium phosphidotetracarbonylferrates which can be alkylated or acylated at phosphorus.     

Preparation and properties of (η-C5H5)2ZrCl[Si(CH3)3] and (η-C5H5)2Zr[Si(CH3)3]2; trimethylsilyl group transfer from mercury to zirconium

Two silyl-zirconium compounds (η-C₅H₅)₂ZrCl[Si(CH₃)₃] (I) and (η-C₅H₅)₂-Zr[Si(CH₃)₃]₂ (II), have been prepared by the reaction of (η-C₅H₅)₂ZrCl₂ with Hg[Si(CH₃)₃]₂ in refluxing benzene. While I is unreactive toward 1-hexyne (55–60°C) and CO (350 psi), the zirconiumsilicon bond is cleaved by electrophiles such as Cl₂, HgCl₂, and AlCl₃.     

Re4(CO)12[μ3-InRe(CO)5]4 und Re2(CO)8[μ-InRe(CO)5]2-cluster aus dem reaktionssystem In/Re2(CO)10 in xylol

The thermally stable solids Re₂(CO)₈[μ-InRe(CO)₅]₂ and Re₄(CO)₁₂[μ₃-InRe(CO)₅]₄ could be obtained by treatment of In with Re₂(CO)₁₀ in a bomb tube. A mechanism of the formation of the latter cluster from the first one is proposed. Compared with Re₂(CO)₈[μ-InRe(CO)₅]₂, Re₄(CO)₁₂[μ₃_InRe(CO)₅]₄ shows in polar solvents an unusual high stability, which can be explained by the higher coordination number of In with rhenium carbonyl ligands. Re₄(CO)₁₂-[μ₃-InRe(CO)₅]₄ dissolves monomerically in acetone, where as Re₂(CO)₈[μ-InRe(CO)₅]₂ dissociates yielding Re(CO)₅^? anions. Single-crystal X-ray analyses of Re₄(CO)₁₂[μ₃-InRe(CO)₅]₄ establish the metal skeleton. The central molecular fragment Re₄(CO)₁₂ contains a tetrahedral arrangement of four bonded Re atoms [ReRe 302.8 (5) pm]. The triangles of this fragment are capped with a μ₃-InRe(CO)₅ group each [InRe(terminal) 273.5 (7) pm; InRe (polyhedral) 281.8 (7) pm]. The bridging type of In atoms with the Re₄ tetrahedron and the metal skeleton was realized for the first time. By treating Re₄(CO)₁₂[μ₃-InRe(CO)₅]₄ with Br₂ the existence of Re(CO)₅ ligands could be proved by isolating BrRe(CO)₅.     

Improved syntheses of Ru(CO)2 (O3SCF3)2 (bidentate) complexes and their conversion into new [Ru(CO)2 (bidentate)2]2+ complexes

Reaction of the complexes Ru(CO)₂Cl₂L [L = 2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen)] with trifluoromethanesulphonic acid under carefully controlled conditions yields Ru[cis-(CO)₂] [cis-(O₃SCF₃)₂] (bidentate complexes. From reactions of the trifluoromethanesulphonates with the appropriate bidentate ligands, the new complexes [cis-Ru(CO)₂-L(L′)]²⁺ (L as above; L′ = 4,4′-dimethyl-2,2′-bipyridyl or 4,4′-diisopropyl-2,2′-bipyridyl) as well as the known [_cis-Ru(CO)₂L₂]²⁺ and [cis-Ru(CO)₂bpy(phen)]²⁺ have been prepared.