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.     

Synthesis, structure and reactivity of [(CF3)3GePt(PPh3)2]2Hg

The reaction of Pt(PPh₃)_n (n = 3 or 4) with [(CF₃)₃Ge]₂Hg or (CF₃)₃GeHgPt(PPh₃)₂Ge(CF₃)₃ (I) gives a stable diplatinum complex [(CF₃)₃GePt(PPh₃)₂]₂Hg (II). X-Ray analysis has established that compound II contains a Ge---Pt---Hg---Pt---Ge chain of C₂ symmetry. Both of the Pt atoms have distorted square-planar coordinations. The bond lengths are: Pt---Hg, 2.630(2) and 2.665(2) Å; Ge---Pt, 2.410(4) and 2.407(4) Å.

Compound II reacts with dihydrogen in THF solution under mild conditions to give mercury and the hydride (CF₃)₃GePt(PPh₃)₂H. On interaction of II with R₂Hg organomercurials (R = Cl, Et, GeEt₃, Ge(CF₃)₃, Ge(C₆F₅)₃) an unknown reaction takes place: Pt(PPh₃)₂ moieties migrate from the polymetallic grouping into the substrate with the formation of the corresponding RHgPt(PPh₃)₂R complexes or their demercuration products, R₂Pt(PPh₃);, (R = Cl, Et). The latter react further with complex I formed in the first step of the process to give Hg and (CF₃)₃GePt(PPh₃)₂R. The reaction schemes are discussed.     

Mixed-metal cluster chemistry VI: Phosphine substitution at CpMoIr3(μ-CO)3(CO)8; X-ray crystal structure of CpMoIr3(μ-CO)3(CO)7(PPh3)

Reactions of CpMoIr₃(μ-CO)₃(CO)₈ (1) with stoichiometric amounts of phosphines afford the substitution products CpMoIr₃(μ-CO)₃(CO)_8−x (L)_x (L = PPh₃, x = 1 (2), 2 (3); L = PMe₃, x = 1 (4), 2 (5), 3 (6)) in fair to good yields (23–54%); the yields of both 3 and 6 are increased on reacting 1 with excess phosphine. Products 2–5 are fluxional in solution, with the interconverting isomers resolvable at low temperatures. A structural study of one isomer of 2 reveals that the three edges of an MoIr₂ face of the tetrahedral core are spanned by bridging carbonyls, and that the iridium-bound triphenyiphosphine ligates radially and the molybdenum-bound cyclopentadienyl coordinates axially with respect to this Molr₂ face. Information from this crystal structure, ³¹P NMR data (both solution and solid-state), and results with analogous tungsten—triiridium and tetrairidium clusters have been employed to suggest coordination geometries for the isomeric derivatives.     

Synthesis and characterization of Na5[Co(CO)3(P{(CH2)nC6H4-P-SO3}3)2], n = 1, 2, 3, and 6. Novel zwitterion

The electron donating water soluble phosphines, P{(CH₂)nC₆H₄-p-SO₃Na}₃,n = 1, 2, 3 and 6, react rapidly with Co₂(CO)₈ under two phase reaction conditions to yield the disproportionation products, [Co(CO)₃(P{(CH₂)nC₆H₄-p-SO₃Na₃}₂] [Co(CO)₄]. Selective precipitation yields the formally zwitterionic complex anions as the sodium salt, [Co(CO)₃(P{(CH₂)nC₆H₄-p-SO₃} ₃)₂]⁵⁻. The anions can be used as precursors to water soluble cobalt hydroformylation catalysts under two phase and supported aqueous phase conditions. The tendency to form alcohol products is low with these complexes. The behavior of the catalysts is consistent with an active species that remains water soluble during the reaction and is not leached into the nonaqueous phase.     

Melting and thermal decomposition of [Ni(H2O)6](NO3)2

The two-stage melting process and the thermal decomposition of [Ni(H₂O)₆](NO₃)₂ was studied by DSC, DTA and TG. The first melting point at 328 K is connected with the small and the second melting point at 362 K with the large enthalpy and entropy changes. The thermal dehydration process starts just above ca. 315 K and continues up to ca. 500 K. It consists of three well-separated stages, but the sample mass loss at each stage depends on the experimental regime. However, irrespective of the chosen regime, the total of registered mass losses in stage one and two amounts to three H₂O molecules per one [Ni(H₂O)₆](NO₃)₂ molecule. The remaining three H₂O molecules are gradually freed in the temperature range of 440–500 K in the third stage of the dehydration. Above 580 K, anhydrous Ni(NO₃)₂ decomposes into NO and NiO. The gaseous products were identified by quadrupole mass spectrometer (QMS), and the solid product was identified by X-ray diffraction (XRD) analysis.     

Synthesis and molecular structure of Ba5(μ5-OH)[μ3-OCH(CF3)2]4[μ2-OCH(CF3)2]4 [OCH(CF3)2](THF)4(H2O)·THF: a source of barium fluoride

The reaction between metallic barium and fluoroisopropanol or alcoholysis of [Ba(OPrⁱ)₂] produces a pentanuclear fluoroalkoxide. Its X-ray structure determination showed its formulation to correspond to Ba₅(μ₅-OH)[μ₃-OCH(CF₃)₂]₄[μ₂-OCH(CF₃)₂]₄ [OCH(CF₃)₂](THF)₄(H₂O)·THF. The metallic core is based on a square pyramid encapsulating an hydroxo ligand. In addition to the barium---alkoxide bonds [2.53(3)–2.86(3) Å] neutral O-donors, four THF [2.82(2)–2.86(3) Å] and one H₂O [2.79(3) Å] and secondary barium---fluorine interactions [2.99(2)–3.31(2) Å] ensure high coordination numbers, from 9 to 11 for the metal centers. Hydrogen bonding between the apical fluoroisopropoxide, the water molecule and one THF molecule, non-bonded to a metal center, accounts for the stability of the hydrate and illustrates the Lewis acidity of fluoroalkoxides. Thermal decomposition leads to BaF₂.     

Vibrational study of hydrogen bonding and structural disorder in Na2H(SO4)2, K3H(SO4)2 and (NH4)3H(SO4)2 crystals

Infrared and Raman spectra on Na₃H(SO₄)₂, K₃ H(SO₄)₂ and (NH₄)₃ H(SO₄)₂ crystals have been investigated at 300 and 100 K in the 4000 to 30 cm⁻¹ region. An assignment of bands in terms of OH group frequencies and more or less distorted tetrahedra of ammonium and sulphate ions is given. The crystallographic and spectroscopic symmetry and/or dissymetry of OHO hydrogen bonds linking sulphate ions into dimers is discussed using OH group frequencies and the splitting of the v₁ (SO₄) Raman bands as criteria. In the particular case of (NH₄)₃H(SO₄)₁ compound containing several solid phases it can be shown that the room temperature phase (II) is strongly disordered, principally because of an orientational disorder of ammonium ions, and that a progressive ordering takes place with temperature lowering.     

Syntheses and X-ray crystal structures of [Co(η-CO3)(NH3)4](NO3)·0.5H2O and [(NH3)3Co(μ-OH)2(μ-CO3)Co(NH3)3][NO3]2·H2O

[Co(η²-CO₃)(NH₃)₄](NO₃)·0.5H₂O and [(NH₃)₃Co(μ-OH)₂(μ-CO₃)Co(NH₃)₃][NO₃]₂·H₂O were prepared by prolonged aerial oxidation of a solution of Co(NO₃)₂·6H₂O and ammonium carbonate in aqueous ammonia. The formation of these side products highlights the richness of the chemistry of these systems and the possibility of by products if methods are not strictly adhered to. The X-ray crystal structures of [Co(η²-CO₃)(NH₃)₄][NO₃]·0.5H₂O and [(NH₃)₃Co(μ-OH)₂(μ-CO₃)Co(NH₃)₃][NO₃]₂·H₂O reveal a monomeric octahedral cobalt center with η²-bound CO₃²⁻ in the former, while the latter consists of a dimeric array where the two cobalt centers are bridged by two OH⁻ and one μ₂-CO₃²⁻ groups with three terminal NH₃ ligands for each Co center. In both complexes extensive hydrogen bonding interactions are evident.     

Structure and properties of the dinuclear complex [Co2(μ-OAc)2(OAc)2(μ-H2O)(phen)2]

The dinuclear complex [Co₂(μ-OAc)₂(OAc)₂(μ-H₂O)(phen)₂] has been prepared and its structure was determined. The compound crystallizes in the monoclinic space group P2(1)/c. The Co–Co distance is 3.574 Å and is similar to the Fe–Fe distance in the reduced methane monooxygenase hydroxylase. The electronic and IR spectra of the complex confirm octahedral coordination of the cobalt atoms and formation of strong O–HO hydrogen bonds in the solid state. The dependence of the magnetic susceptibility of the complex on temperature indicates an antiferromagnetic interaction, the value of the isotropic exchange parameter J was estimated to be −2.1 cm⁻¹. The ¹H NMR spectra show that in organic solvents the structure of compound is the same as in the solid state, however, in water solution the complex dissociates giving compounds with different Co:phen ratios.     

Tetrakis(triphenylphosphine oxide) complexes of the lanthanide nitrates; synthesis, characterisation and crystal structures of [La(Ph3PO)4(NO3)3]·Me2CO and [Lu(Ph3PO)4(NO3)2]NO3

The reaction of Ln(NO₃)₃·6H₂O (Ln=La, Ce, Pr or Nd) with a sixfold excess of Ph₃PO in acetone formed [Ln(Ph₃PO)₄(NO₃)₃]·Me₂CO. The crystal structure of the La complex shows a nine-coordinate metal centre with four phosphine oxides, two bidentate and one monodentate nitrate groups, and PXRD studies show the same structure is present in the other three complexes. In CH₂Cl₂ or Me₂CO solutions, ³¹P NMR studies show that the complexes are essentially completely decomposed into [Ln(Ph₃PO)₃(NO₃)₃] and Ph₃PO. Similar reactions in ethanol gave [Ln(Ph₃PO)₃(NO₃)₃] only. In contrast for Ln=Sm, Eu or Gd, only the [Ln(Ph₃PO)₃(NO₃)₃] are formed from either acetone or ethanol solutions. For the later lanthanides Ln=Tb–Lu, acetone solutions of Ln(NO₃)₃·6H₂O and Ph₃PO gave [Ln(Ph₃PO)₃(NO₃)₃] only, even with a large excess of Ph₃PO, but from cold ethanol [Ln(Ph₃PO)₄(NO₃)₂]NO₃ (Ln=Tb, Ho–Lu) were obtained. The structure of [Lu(Ph₃PO)₄(NO₃)₂]NO₃ shows an eight-coordinate metal centre with four phosphine oxides and two bidentate nitrate groups. In solution in CH₂Cl₂ or Me₂CO the tetrakis-complexes show varying amounts of decomposition into mixtures of [Ln(Ph₃PO)₃(NO₃)₃], [Ln(Ph₃PO)₄(NO₃)₂]NO₃ and Ph₃PO as judged by ³¹P{¹H} NMR spectroscopy. The [Ln(Ph₃PO)₃(NO₃)₃] also partially decompose in solution for Ln=Dy–Lu, forming some tetrakis(phosphine oxide) species.     

Magnetic investigation of Cu(NH3)4(NO3)2

The magnetic properties of Cu(NH₃)₄(NO₃)₂ have been measured at low temperatures. Broad maxima in both the susceptibility and specific heat are observed and are consistent with linear chain behavior of a Heisenberg antiferromagnet, with J/k = 3.9 ± 0.1 K. Long-range order sets in at T_c = 0.15 ± 0.01 K, and the ratio kT_c/|J| = 0.038 is the lowest observed as yet for a one-dimensional, S = 1/2 antiferromagnet.     

Equilibrium diagram of KPO3–Y(PO3)3 system, chemical preparation and characterization of KY(PO3)4

Microdifferential thermal analysis (μ-DTA), X-ray diffraction (XRD) and infrared (IR) spectroscopy were used for the first time to investigate the liquidus and solidus relations in the KPO₃–Y(PO₃)₃ system. The only compound observed within the system was KY(PO₃)₄ melting incongruently at 1033 K. An eutectic appears at 13.5 mol% Y(PO₃)₃ at 935 K, the peritectic occurs at 1033 K and the phase transition for potassium polyphosphate KPO₃ was observed at 725 K. Three monoclinic allotropic phases of the single crystals were obtained. KY(PO₃)₄ polyphosphate has the P2₁ space group with lattice parameters: a=7.183(4) Å, b=8.351(6) Å, c=7.983(3) Å, β=91.75(3)° and Z=2 is isostructural with KNd(PO₃)₄. The second allotropic form of KY(PO₃)₄ belongs to the P2₁/n space group with lattice parameters: a=10.835(3) Å, b=9.003(2) Å, c=10.314(1) Å, β=106.09(7)° and Z=4 and is isostructural with TlNd(PO₃)₄. The IR absorption spectra of the two forms show a chain polyphosphates structure. The last modification of KYP₄O₁₂ crystallizes in the C2/c space group with lattice parameters: a=7.825(3) Å, b=12.537(4) Å, c=10.584(2) Å, β=110.22(7)° and Z=4 is isostructural with RbNdP₄O₁₂ and contains cyclic anions. The methods of chemical preparations, the determination of crystallographic data and IR spectra for these compounds are reported.     

Geometrical isomerization of fac/mer-Mo(CO)3(phosphite)3 and cis/trans-Mo(CO)4(phosphite)2 catalyzed by Me3SiOSO2CF3

Geometrical isomerization of fac-Mo(CO)₃L₃ (L = P(OPh)₃, P(OMe)₃, P(OEt)₃) to the mer form and that of cis-Mo(CO)₄L₂ (L = P(OPh)₃, P(OMe)₃, PPh₂(OMe)) to the trans form were observed in CH₂Cl₂ at room temperature in the presence of a catalytic amount of Me₃SiOSO₂CF₃ (TMSOTf). Crossover experiments suggest that a ligand dissociation is not involved in the isomerization. A catalytic cycle involving an interaction of the silicon atom in Me₃Si⁺ with one oxygen in P(OR)₃ ligands has been proposed. The first isolation and the X-ray structure analysis were attained for mer-Mo(CO)₃{P(OPh)₃}₃ through the TSMOTf-assisted isomerization of fac-Mo(CO)₃{P(OPh)₃}₃.     

Synthesis and structural characterization of (μ-H)2RU3(CO)9(μ3-η-C8H12) and (μ-H)RU3(CO)9(μ3-η-C12H19)

The reaction between Ru₃(CO)₁₂ and a cyclic olefin (cis-cyclooctene or trans-cyclododecene) at 100 °C for several hours gives the title compounds (μ-H)₂RU₃(CO)₉(μ₃-η²-C₈H₁₂) (1), and (μ-H)RU₃(CO)₉(μ₃-η³-C₁₂H₁₉) (2), both of which have been characterized by X-ray diffraction studies, IR and NMR spectral measurements and elemental analysis. The prolonged reaction between Ru₃(CO)₁₂ and cis-cyclooctene gives compound HRu₃(CO)₉(C₈H₁₁) (3). Compound 3 has been characterized with IR and NMR spectral analyses. In 1 the cyclooctene ring is linked via a μ₃-η²-alkyne type of bonding to the face of the Ru₃ cluster. It is formally σ-bonded to two of the three Ru atoms and π-bonded to the third Ru. The two hydrides in 1 are bridging Ru---Ru bonds. In 2 the cyclododecene ring is bonded to the Ru₃ face via the μ₃-η³-CCHC linkage. There are two formal σ-bonds from the allyl part to the hydrido-bridged Ru atoms and the η³-allyl linkage to the third Ru atom.     

The reactivity of dimethylaluminum hydride with the aminoarsines Me2AsNMe2, MeAs(NMe2)2, and As(NMe2)3

The reactions of (Me₂AlH)₃ with Me₂AsNMe₂, MeAs(NMe₂)₂, and As(NMe₂)₃ were investigated as a function of time at room temperature and over the temperature range −90 to 24°C by use of ¹H and ¹³C NMR spectroscopy. (Me₂AlH)₃ was found to be very reactive toward the aminoarsines, even at −90°C, and no stable Me₂AlH-aminoarsine adducts were observed. Instead, the initial stages of the reactions involved AS---N bond cleavage with the generation of highly reactive AlN- and AsH-bonded species. The subsequent course of each reaction and the final arsenic-containing product distribution depended upon the original AL:N stoichiometric ratio and the respective aminoarsine. When the Al:N ratio was 1:1, the reactions were straightforward for each aminoarsine. However, in every case, [Me₂AlNMe₂]₂ was the final AlN-containing product. Independent reactions were carried out to verify many of the proposed decomposition pathways that lead to thermodynamically stable products. The results of this study are compared with those of the analogous, previously reported (Me₃Al)₂-aminoarsine systems. Additionally, a new synthetic route to [Me₂AlAsMe₂]₃ has been established from the reaction of (Me₂AlH)₃ with Me₂AsH.     

The ternary system H2O–Fe(NO3)3–Co(NO3)2 isotherms 0 and 15 °C

The solid–liquid equilibria of the ternary system H₂O–Fe(NO₃)₃–Co(NO₃)₂ were studied by using a synthetic method based on conductivity measurements.

Two isotherms were established at 0 and 15 °C, and the stable solid phases which appear are the iron nitrate nonahydrate (Fe(NO₃)₃·9H₂O), the iron nitrate hexahydrate (Fe(NO₃)₃·6H₂O), the cobalt nitrate hexahydrate (Co(NO₃)₂·6H₂O) and the cobalt nitrate trihydrate (Co(NO₃)₂·3H₂O).     

Multiple ligand transfer reaction between [CpRu(L)(AN)2][PF6] (L=AN, CO, P(OMe)3; AN=acetonitrile) and CpFe(CO)L′X (L′=CO, PMe3, PMe2Ph, PMePh2, PPh3, P(OPh)3; X=Cl, Br, I)

Treatment of ruthenium complexes [CpRu(AN)₃][PF₆] (1a) (AN=acetonitrile) with iron complexes CpFe(CO)₂X (2a–2c) (X=Cl, Br, I) and CpFe(CO)L′X (6a–6g) (L′=PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(OPh)₃; X=Cl, Br, I) in refluxing CH₂Cl₂ for 3 h results in a triple ligand transfer reaction from iron to ruthenium to give stable ruthenium complexes CpRu(CO)₂X (3a–3c) (X=Cl, Br, I) and CpRu(CO)L′X (7a–7g) (L′=PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(OPh)₃; X=Br, I), respectively. Similar reaction of [CpRu(L)(AN)₂][PF₆] (1b: L=CO, 1c: P(OMe)₃) causes double ligand transfer to yield complexes 3a–3c and 7a–7h. Halide on iron, CO on iron or ruthenium, and two acetonitrile ligands on ruthenium are essential for the present ligand transfer reaction. The dinuclear ruthenium complex 11a [CpRu(CO)(μ-I)]₂ was isolated from the reaction of 1a with 6a at 0°C. Complex 11a slowly decomposes in CH₂Cl₂ at room temperature to give 3a, and transforms into 7a by the reaction with PMe₃.     

Synthesis and structural behavior of the P-functional organotin chlorides [Ph2P(CH2)3]2SnCl2, Ph2P(CH2)3SnCl2Me, and Ph2P(CH2)nSnCl3 (n=2, 3)

The P-functional organotin dichloride [Ph₂P(CH₂)₃]₂SnCl₂ (3) is synthesized by reaction of Ph₂P(CH₂)₃MgCl with SnCl₄ independently of the molar ratio of the starting compounds. The corresponding organotin trichlorides Ph₂P(CH₂)_nSnCl₂R (4: n=2, R=Cl; 5: n=3, R=Cl; 6: n=3, R=Me) are formed in a cleavage reaction of Ph₂P(CH₂)_nSnCy₃ (n=2, 3) with SnCl₄ or MeSnCl₃, respectively. The main features of the crystal structures of 3–6 are both intra- and intermolecular PSn coordinations and the existence of intermolecular Sn---ClSn bridges. For further characterization of the title compounds, the adducts 4(Ph₃PO)₂ (7) and 5(Ph₃PO) (8), as well as the P-oxides and P-sulfides of 3–6 (9–15), are synthesized. The results of crystal structure analyses of 7, 11, 12, and 14 are reported. The structures of 9–15 are characterized by intramolecular P=XSn interactions (X=O, S). A first insight into the structural behavior of the compounds 3–15 in solution is discussed on the basis of multinuclear NMR data.     

Synthesis and chemistry of the bis(trimethylsilyl)amido bis-tetrahydrofuranates of the group 2 metals magnesium, calcium, strontium and barium. X-ray crystal structures of Mg[N(SiMe3)2]2·2THF and related Mn[N(SiMe3)2]2·2THF

Transamination reactions utilizing the compound mercuric bis(trimethylsilyl)amide, Hg{N(SiMe₃)₂}₂, in tetrahydrofuran (THF), and the metals Na, Mg, Ca, Sr, Ba and Al have been investigated. Thus the THF solvated compounds Na[N(SiMe₃)₂]·THF and M[N(SiMe₃)₂]₂·2THF, M = Mg, Ca, Sr and Ba (1–4), have been prepared. The X-ray crystal structures of 1 and the related manganese compound Mn[N(SiMe₃)₂]₂·2THF (5) are reported. Interaction of the silylamides, 2–4, with a range of crown ethers apparently proceeded with elimination of silylamine, (Me₃Si)₂NH, and novel ring opening of the crown ethers, generating species containing a donor alkoxide ligand with a vinyl ether function, presumably, ---O(CH₂CH₂O)_nCH=CH₂ (n = 3−5). The silylamides 2–4 were also cleanly converted to the corresponding alkoxides (from ¹H NMR data) in reactions with stoichiometric quantities of 3-ethyl-3-pentanol.     

Influence of the modification of the ligands on hex-1-ene hydroformylation catalyzed by [HRh{P(OPh)3}4] and [HRh(CO){P(OPh)3}3]. Catalytic activity of the sytem [HRh}P(OPh)3}4]+Cp2Zr(CH2PPh2)2

A study has been carried out of the catalytic activity of the systems formed by [HRh{P(OPh)₃}₄] or [HRh(CO){P(OPh)₃}₃] with the modifying ligands P(OPh)₃, PPh₃, diphos and Cp₂Zr(CH₂PPh₂)₂ in hydroformylation of hex-1-ene (at p = 5 bar). The best results were obtained with the system [HRh{P(OPh)₃}₄]+Cp₂Zr(CH₂PPh₂)₂ (75–85% yeild of aldehydes).