Synthesis and molecular structure of hydrido(tetrahydroborato)(1,1,1-tris(diphenylphosphinomethyl)ethane)-iron(II)

Sodium tetrahydroborate reacts with iron(II) tetrafluoroborate and 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) to give the complex (triphos)-FeH(BH₄) whose molecular structure, determined from X-ray data consists of monomolecular units in which the iron atom is six-coordinated by the three phosphorus atoms of the ligand, two hydrogen atoms of the BH₄ group, and a hydridic hydrogen atom. Variable temperature ³¹P NMR spectra reveal stereochemical non-rigidity of the complex in solution.     

The crystal and molecular structure of the dimethylplatinum(II) complex of 1,1,1-tris(diphenylphosphinomethyl)ethane

A new crystal X-ray study, as well as proton and phosphorus-31 NMR studies, show that the structure of Pt(CH₃)₂(tripod) [tripod = 1,1,1-tris(diphenylphosphinomethyl)ethane] consists of a four-coordinate, nearly planar platinum with the triphosphine functioning as a bidentate ligand.     

Paramagnetic carbonyl cobalt(II) complexes. Molecular structure of bromocarbonyl-1,1,1-tris(diphenylphosphinomethyl)ethanecobalt(II) tetraphenylborate

Carbon monoxide or cyclohexyl isonitrile (L) react with the dinuclear five-coordinated derivatives of 1,1,1-tris(diphenylphosphinomethyl)ethane, (triphos), [(triphos)Co(μ-X)₂Co(triphos)](BPh₄)₂ (X = halide) to give complexes of formula [(triphos)Co(L)X]BPh₄. The latter are rare examples of paramagnetic cobalt(II) carbonyl complexes. The molecular structure of [(triphos)Co(CO)Br]BPh₄ has been determined from counter diffraction data. The crystals are monoclinic, space group P2₁/a with cell dimensions a 20.225(8), b 20.664(9), c 13.301(5); β 97.24(5)°, D_c = 1.338 g cm^?3 for Z = 4. Full-matrix least squares refinement led to the conventional R factor of 0.057 for 3648 observed reflections. The molecular structure consists of five-coordinate [(triphos)Co(CO)Br]⁺ cations of intermediate geometry and BPh^?₄ anions.     

Crystal structure of the solid solution of 1,1,1-tris(diphenylphosphinomethyl)propane and its phosphine oxide analogs

The crystal and molecular structure of the solid solution of 1,1,1-tris(diphenylphosphinomethyl)propane and its phosphine oxide analogs C₄₂H₄₁O_0.64P₃ (I) was determined by X-ray diffraction analysis; space group P1, a = 10.945(3), b = 11.277(2), c = 15.985(6) Å, α = 76.10(2), β = 72.03(2), γ = 71.71(2)°, Z = 2. Structure I was solved by direct methods and refined by the full-matrix least-squares procedure in an anisotropic approximation to R = 0.045 for all 5227 unique measured reflections (CAD-4 automatic diffractometer, λCuK_α). Low-occupied phosphoryl O sites are found near each of the three P atoms in structure I. The total occupancy of the three O sites is 0.64(1), from which it follows that the contents of the - CH₂PPh₂ and - CH₂P(O)Ph₂ fragments in I are 78.6 and 21.4%, respectively. In averaged (mixed) molecule I, all P=O bonds were obtained effectively shortened, and the average P-C bonds P-C(sp³) and P-C(ar) equal 1.846 and 1.834 Å, respectively.     

Crystal structure of the solid solution of 1,1,1-tris(diphenylphosphinomethyl)propane and its phosphine oxide analogs

The crystal and molecular structure of the solid solution of 1,1,1-tris(diphenylphosphinomethyl)propane and its phosphine oxide analogs C₄₂H₄₁O_0.64P₃ (I) was determined by X-ray diffraction analysis; space group P1, a = 10.945(3), b = 11.277(2), c = 15.985(6) ?, α = 76.10(2), β = 72.03(2), γ = 71.71(2)°, Z = 2. Structure I was solved by direct methods and refined by the full-matrix least-squares procedure in an anisotropic approximation to R = 0.045 for all 5227 unique measured reflections (CAD-4 automatic diffractometer, λCuK_α). Low-occupied phosphoryl O sites are found near each of the three P atoms in structure I. The total occupancy of the three O sites is 0.64(1), from which it follows that the contents of the - CH₂PPh₂ and - CH₂P(O)Ph₂ fragments in I are 78.6 and 21.4%, respectively. In averaged (mixed) molecule I, all P=O bonds were obtained effectively shortened, and the average P-C bonds P-C(sp³) and P-C(ar) equal 1.846 and 1.834 ?, respectively. Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 4, pp. 788-794, July-August, 2000     

Synthesis and Characterization of 2,4,6-tris(hydrazino)-s-triazine and its Metal Complexes

A new multidentate ligand related to s-triazine herbicides 2,4,6-tris(hydrazino)-s-triazine (THSTZ) and its metal complexes was synthesized. The complexes were investigated by m.s., n.m.r., i.r., u.v.–vis and AA spectroscopic techniques. Furthermore, carbon, nitrogen, hydrogen, chloride, and metal analyses, conductivity, magnetic susceptibility measurements, and thermal analyses were carried out. The Co(II), Ni(II), Cu(I), and Zn(II) metal complexes were synthesized in methanolic media. Metal-to-ligand ratios were found to be 1:1 for Co(II) and Zn(II), 2:1 for Cu(I) and 3:2 for Ni(II) complexes. N.m.r. spectral and thermal analyses showed the presence of MeOH in all of the complexes. Conductivity measurements suggested that the complexes were 1:2 electrolytes. Ring nitrogens as well as the terminal nitrogens of hydrazine side chains in THSTZ were proposed as metal binding centres. Magnetic moments of Ni(II) (4.12μ_B) and Co(II) (4.2μ_B) indicate tetrahedral and octahedral geometry, respectively. Tetrahedral geometry for Cu(I) and Zn(II) complexes was suggested. V. J. T. Raju - Previously working as Professor of Chemistry, Osmania University, Hyderbad, India     

Copper(I)-1,1,1-tris(diphenylphosphinomethyl)ethane complexes with different coordination modes tuned by auxiliary ligands and their spectroscopic properties

Three mono-, bi- and tetranuclear copper(I) complexes, [Cu(phen)(triphos-O)]BF₄ (1) (phen = 1,10-phenanthroline, triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane), [Cu₂(bipy)(triphos)₂](BF₄)₂ (2) (bipy = 4,4′-bipyridine), and [Cu₄(MeOC^N^N)₄(triphos)₂(bipy)](BF₄)₄ (3) (MeOC^N^N = 6-(4-methoxyphenyl)-2,2′-bipyridine), have been synthesized and characterized by NMR spectroscopy, electrospray ionization, and matrix-assisted laser desorption ionization time-of-flight mass spectrometries, elemental analysis, and X-ray crystal analysis. The crystal structure investigation revealed the copper ions of the complexes have pseudo-tetrahedral coordination geometry. The electronic absorption spectra of 1, 2, and 3 contain low-energy bands at 350–500 and 400–650 nm, which are assigned to d(Cu) → π*(phen or bipy) and a mixture of d(Cu) → π*(MeOC^N^N) and d(Cu) → π*(bipy) transitions, respectively. Complex 2 displays a strong, long-lived solid-state emission with a maximum at 555 nm and lifetime of 13.6 μs at room temperature. Photoinduced electron-transfer properties of 2 and 3 involving nanosecond time-resolved absorption spectroscopy and electron spin resonance techniques were studied.     

2-Trifluoromethylimidazole, 2,4,5-tris (trifluoromethyl)imidazole and related compounds

2-Trifluoromethylimidazole, prepared by the reaction of imidazole-2-carboxylic acid with sulphur tetrafluoride, afforded a silver salt which reacted with organohalides (bromomethane, ethyl bromoacetate, N,N-dimethyl-2-chloroethylamine, and chloroacetonitrile) to give the corresponding N-alkylated derivatives. 2-Trifluoromethylimidazole-4,5-dicarboxylic acid was obtained by oxidation of 2-trifluoromethylbenzimidazole, and on decarboxylation gave only traces of 2-trifluoromethylimidazole; the major product was 2-trifluoromethylimidazole- 4-carboxylic acid. The di-acid and sulphur tetrafluoride gave 2,4,5-tris (trifluoromethyl) imidazole.     

[(R)-2-Methyl-1,4,7-triazacyclononane] [1,1,1-tris(aminomethyl)ethane]-cobalt(III) and some Mono[(R)-2-methyl-1,4,7-triazacyclononane]-cobalt(III) Complexes

Summary [(R)-2-Methyl-1,4,7-triazacyclononane][1,1,1-tris(aminomethyl)ethane]cobalt(III) has been prepared and separated into two isomers which show weak Cotton effects in the¹A₁¹T₁ region (d-electron transition) compared with that of bis[(R)-2-methyl-1,4,7-triazacyclononane]cobalt(III). The effect is comparable to that of tetraammine[(R)-1,2-diamino propane]cobalt(III). The circular dichroism spectra of the mono complex change markedly upon addition of sodium sulphate. The chelate rings are more flexible in the mono than in the bis complex. Some other related mono[(R)-2-methyl 1,4,7-triazacyclononane]cobalt(III) and [(R)-2-methyl-1,4,7 triazacyclononane][1,1,1-tris(aminomethyl)ethaneI nickel (II) complexes have also been prepared and characterized.     

Tripodal compound 1,1,1-tris(N-ethyl-N-phenylamino-carboxylmethoxymethyl) propane as an ionophore for alkali and alkaline earth metal cations-selective electrode

A new tripodal compound, 1,1,1-tris(N-ethyl-N-phenylamino-carboxylmethoxymethyl) propane, has been synthesized and evaluated as an ionophore in PVC membrane electrode for the analysis of alkali and alkaline earth metal cations. The influence of the nature of the plasticizers (o-NPOE, DBP and DOP) and of the amount of incorporated ionophore on the characteristics of the electrode was discussed. Selectivity coefficients against alkali and alkaline earth metal cations were calculated. The electrodes based on the tripodal compound with o-NPOE and DBP as plasticizer gave good performance (slope, limits of detection) to lithium and sodium ions. The electrode plasticized with o-NPOE also exhibited near-Nernstian response to divalent ions: Ca(2+), Sr(2+) and Ba(2+). The electrode prepared with 3.9 mg ionophore, 185 mg o-NPOE, 92 mg PVC and 0.46 mg KTpClPB can be used as a Ca(2+) electrode. The influence of pH has also been studied. The electrodes exhibited better potential stability and operational lifetime of more than 3 months.     

Electrospray mass spectra of group 6 (Fischer) carbenes in the presence of electron-donor compounds

Fischer carbene complexes 1-7 are not ionized under standard electrospray ionization (ESI) conditions. We report here that unsaturated chromium and tungsten (Fischer) carbene complexes can be ionized in an electrospray ion source in the presence of electron-donor compounds such as hydroquinone (HQ) or tetrathiafulvalene (TTF). The addition of these compounds, which seem to act as electron transfer agents, permits the recording and study of their ESI mass spectra in the negative mode of detection. Both chromium and tungsten(0) carbene complexes undergo in the first fragmentation stage a double simultaneous decarbonylation process.     

Komplexchemie polyfunktioneller liganden : XXXVII. Darstellungsmethoden für hydrido-kobalt(I)-komplexe des 1,1,1-tris(diphenylphosphinomethyl)äthans

[Co(CO)₂(R₂PCH₂)₃CCH₃][Co(CO)₄] (R  C₆H₅) reacts with NaBH₄, depending on the reaction conditions, to give CoH(CO)₂(R₂PCH₂)₂C(CH₃)CH₂PR₂ · BH₃ and CoH(CO)(R₂PCH₂)₃CCH₃. The hydride CoH(CO)(R₂PCH₂)₃CCH₃ is also formed by the reaction of [Co(CO)₂(R₂PCH₂)₃CCH₃][Co(CO)₄] with LiOH, NaOH and NaNH₂. The reaction with LiOH primarily gives (acetone)₃-LiCo(CO)(R₂PCH₂)₃CCH₃, which is also formed by reduction of [Co(CO)₂(R₂PCH₂)₂C(CH₃)CH₂PR₂]₂ with lithium in THF/acetone solution. In liquid ammonia [Co(CO)₂(R₂PCH₂)₃CCH₃][Co(CO)₄] at 20°C yields Co(CONH₂)(CO)(R₂PCH₂)₃CCH₃. This compound reacts in the same solvent at 60°C to yield the hydride CoH(CO)(R₂PCH₂)₃CCH₃. CH₃I and HClO₄ react with CoH(CO)(R₂PCH₂)₃CCH₃ yielding CoI(R₂PCH₂)₃CCH₃ and the unstable [Co(H)₂(CO)(R₂PCH₂)₃CCH₃]ClO₄, respectively. The deutero complex CoD(CO)(R₂PCH₂)₃CCH₃ was also synthesized. The new compounds were characterized, as much as possible, by their IR, ¹H NMR and ³¹P NMR data.     

Synthesis of 1,3,5-tris(2-chloroethyl)- and 1,3,5-tris(2-iodoethyl)benzenes

A new method has been elaborated for the synthesis of 1,3,5-tris(2-chloroethyl)- and 1,3,5-tris(2-iodoethyl)benzenes based on the commercially available 1,3,5-tribromobenzene.     

Effect of counter-ion on the thermotropic liquid crystal behaviour of bis(alkyl)-tris(imidazolium salt) compounds

Recently, new thermotropic ionic liquid crystals (LCs) with a hexyl-linked tris(imidazolium bromide) core and two terminal alkyl chains were synthesised and characterised. To explore the effect of different counter-ions on the LC behaviour of this system, derivatives with BF₄^? and Tf₂N^? counter-ions were prepared and analysed. Five of the BF₄^? derivatives were found to exhibit thermotropic LC behaviour. The 12-, 14- and 16-carbon tail BF₄^? compounds form SmA phases. The 18- and 20-carbon tail homologues form what appears to be a smectic phase but are weakly mesogenic and harder to characterise. Only two of the Tf₂N^? derivatives exhibited mesogenic behaviour. The 18-carbon tail Tf₂N^? compound forms an as-yet unidentified, highly periodic smectic phase with positional order while the 20-carbon tail homologue forms a periodic SmA phase. The Tf₂N^? mesogens have much lower clearing points even though their LC phases have more order than the Br^? and BF₄^? mesogens. X-ray diffraction showed that these mesogens have different amounts of tail interdigitation between the smectic layers depending on the counter-ion present. Atomistic molecular dynamics simulations indicated that counter-ion size plays an important role in defining the density of the ionic region, which in turn affects the amount of interdigitation in the smectic phases.