77Se NMR Data Research Articles

Regio- and Stereoselective Synthesis of (Z,Z)-Bis(3-amino-3-oxo-1-propenyl) Selenides and Diselenides Based on 2-propynamides: A Novel Family of Diselenides with High Glutathione Peroxidase-like Activity

The efficient regio- and stereoselective syntheses of (Z,Z)-bis(3-amino-3-oxo-1-propenyl) selenides and diselenides in high yields based on the nucleophilic addition of sodium selenide to 2-propynamides and sodium diselenide to 3-(trimethylsilyl)-2-propynamides have been developed. The first examples of the addition of a selenium-centered nucleophile to 2-propynamides with a terminal triple bond and diselenide anion to 3-(trimethylsilyl)-2-propynamides have been carried out. Bis(3-amino-3-oxo-1-propenyl) diselenides are a novel family of compounds, none of which has yet been described in the literature. The glutathione peroxidase-like activity of the obtained compounds has been evaluated and products with high activity have been found. It was established that diselenides are superior to selenides with the same substituents in glutathione peroxidase-like activity. The results of the structural studying of products by single-crystal X-ray diffraction analysis and 77Se-NMR data are discussed.

ChemInform Abstract: Addition of Selenium(II) Bromide to Arylalkynylamides — A Route to Hypervalent T‐Shaped 10‐Se‐3 Systems.

Abstract A route for the generation of hypervalent T-shaped 10-Se-3 systems is described involving an interaction between in situ prepared selenium(II) bromide and an aryl alkynyl amide derivative. The existence of hypervalent selenium in both the solid and solution states has been supported by X-ray analysis and 77Se NMR data.

Addition of selenium(II) bromide to arylalkynylamides—a route to hypervalent T-shaped 10-Se-3 systems

A route for the generation of hypervalent T-shaped 10-Se-3 systems is described involving an interaction between in situ prepared selenium(II) bromide and an aryl alkynyl amide derivative. The existence of hypervalent selenium in both the solid and solution states has been supported by X-ray analysis and 77Se NMR data.

Transformation of a wobble 2-thiouridine to 2-selenouridine via S-geranyl-2-thiouridine as a possible cellular pathway

The newly discovered S-geranylated 2-thiouridines (geS2U) (Dumelin et al., 2012) and 2-selenouridines (Se2U) were recently shown to be synthesized by a single enzyme (selenouridine synthase, SelU) through two distinct pathways using the same 2-thiouridine substrate (S2U); however, no clear catalytic mechanism was proposed. We suggest that S-geranyl-2-thiouridine is an intermediate of the SelU-catalyzed conversion of S2U to Se2U. The successful chemical transformation of S2U→geS2U→Se2U is demonstrated here as an initial approximation of the intracellular pathway. The structure of Se2U was confirmed by spectroscopic methods, which included, for the first time, 77Se NMR data (δ 354ppm).

Tris(dialkylamino)phosphine Chalcogenide Complexes of Tin(IV) Chloride: A Multinuclear (31P, 77Se, and 119Sn) NMR Characterization

Four octahedral complexes of the type SnCl4.2L [L = (R2N)3P(E): E = Se; R = Me(1), Et(2) and E = S; R = Me(3), Et(4)] have been studied in solution by multinuclear (31P, 77Se, and 119Sn) NMR spectroscopy. 31P and 77Se NMR data were informative of changes associated with complex formation. The solution structure of the complexes was confirmed by their 119Sn NMR spectra that showed two triplet features for each complex, attributed to a mixture of the expected cis and trans isomers. The triplet signal is due to the coupling with two equivalent phosphorus atoms, consistent with an octahedral geometry around the tin center. In addition, density functional theory (DFT)/B3LYP calculations have been carried out to support the interpretations of NMR data. The results are discussed and compared with those reported for related complexes.GRAPHICAL ABSTRACT

Tris(dimethylamino)phosphine Selenide Complexes of Cadmium(II): Synthesis and Multinuclear (31P, 77Se, and 113Cd) NMR Characterization in Solution

The complexes CdL4(ClO4)2 (1), CdL2(NO3)2 (2), and CdL2Cl2 (3) (L = (Me2N)3P(Se)) have been prepared and characterized by elemental analysis, conductivity measurements, IR, and multinuclear (31P, 77Se, and 113Cd) NMR spectroscopy. 31P and 77Se NMR data were informative of changes associated with complex formation. The structure of the prepared complexes was further confirmed in solution by their 113Cd NMR spectra, which show a quintuplet for the perchlorate complex and a triplet for each of the nitrate and chloride complexes due, respectively, to coupling with four and two equivalent phosphorus atoms, consistent with a four coordinate tetrahedral geometry for the cadmium center. The NMR data are discussed and compared with those reported for related complexes.

Synthesis of 3‐Acyl‐1‐alkyl‐2‐alkylseleno‐1‐cyclobutene Using Alkyneselenolate.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of 3-Acyl-1-alkyl-2-alkylseleno-1-cyclobutene Using Alkyneselenolate

The reaction of lithium alkyneselenolate with alpha,beta-unsaturated ketone and then alkyl or acyl halide afforded 3-acyl-1-alkyl-2-alkylseleno-1-cyclobutene. The structure of the cyclobutene was elucidated by IR, MS, (1)H, (13)C, and (77)Se NMR, COSY, HMQC, and HMBC data and X-ray analysis.

Synthesis and cytotoxicity of silylalkylthio‐substituted N‐heterocycles and their hydroselenites

AbstractNew hydroselenites of the different silylalkylthio‐substituted N‐heterocycles have been prepared by the reaction of selenium dioxide with N‐heterocycles in an aqueous medium. Their structure was confirmed by 1H, 13C, and 77Se NMR data. Most of these silylalkylthio‐substituted N‐heterocycles and their hydroselenites have an expressed cytotoxic activity on the MG‐22A (mouse hepatoma), HT‐1080 (human fibrosarcoma), B16 (mouse melanoma), and Neuro 2A (mouse neuroblastoma) cell lines. Some of the hydroselenites exhibit free‐radical protection simultaneously with a high cytotoxic effect. The substances studied were also active in vivoagainst sarcoma S‐180. Copyright © 2003 John Wiley & Sons, Ltd.

Interlayer Structure and Dynamics of ClO4- Layered Double Hydroxides

This paper presents a 35Cl NMR and XRD study of the structure and dynamical behavior of ClO4- intercalated into the interlayers of Mg,Al and Li,Al layered double hydroxides (LDHs). The variable temperature and variable relative humidity (R.H.) 35Cl NMR data show that for these phases ClO4- is rigidly held at low R.H.'s and temperatures, but that at high R.H.s and in pastes at room temperature it undergoes isotropic reorientation at frequencies >103 Hz. Surface and interlayer ClO4- cannot be distinguished. The dynamical behavior is similar for both phases, even though the Li,Al phase swells to a two-water-layer structure but the Mg,Al phase does not. The 35Cl static NMR peak shape is dominated by uniaxial chemical shift anisotropy (CSA) due to the layer structure. These results contrast with previously published 77Se NMR data for interlayer SeO42- in comparable Mg,Al and Li,Al LDHs, which show that SeO42- does not undergo isotropic reorientation at any R.H. SeO42- and ClO4- have similar tetrahedral structu...

Synthesis, structure and cytotoxicity of organoammonium selenites

AbstractNew selenites of different organic bases have been prepared by the reaction of selenium dioxide with aliphatic and heterocyclic amines in an aqueous medium. Their structure was confirmed by 1H, 13C and 77Se NMR data and, in the case of triethanolammonium hydroselenite [HN+(CH2CH2OH)3 HSeO3], by X‐ray analysis. Most of these selenites have an expressed cytotoxic activity on the­MG‐22A (mouse hepatoma), HT‐1080 (human fibrosarcoma), B16 (mouse melanoma), and Neuro 2A (mouse neuroblastoma) cell lines. The substances studied were also active in vivo against sarcoma­S‐180. Copyright © 2002 John Wiley & Sons, Ltd.

Complexation of selenium to (R)‐Rh2(MTPA)4: thermodynamics and stoichiometry

AbstractVariable‐temperature 1H and 77Se NMR data for 3‐phenylselenenyl‐1‐phenyl‐1‐propene (1) in the presence of Rh2(MTPA)4 (Rh*) prove that the equilibria are strongly shifted towards the adduct Rh*···1; free selenide molecules cannot be detected as long as uncomplexed rhodium atoms are available. In the case of excess Rh*, both 1 : 2 and 1 : 1 adducts (Rh* vs 1) are formed, and the latter is slightly favoured. With excess selenide, the system strongly favours the complexation of two selenide molecules (1 : 2 adduct), i.e. one at each rhodium atom. In this situation, intermolecular selenide exchange can be monitored by variable‐temperature 1H NMR spectroscopy and the energy barrier is estimated to be 54–55 kJ mol−1. Copyright © 2001 John Wiley & Sons, Ltd.

Synthesis and multinuclear magnetic resonance investigation of some 1,3‐selenazole and 1,3‐selenazoline derivatives

AbstractThe 1H, 13C, 15N and 77Se NMR data of various annelated 1,3‐selenazoles and ‐1,3‐selenazolines are discussed in terms of tautomerism, configurational and conformational preference as well as HOMO–LUMO transition energies. The interpretations are corroborated by semi‐empirical calculations. Divergencies in solution‐ and solid‐state 77Se NMR data are discussed. Copyright © 2001 John Wiley & Sons, Ltd.

Selenium imides: 77Se NMR investigations of the SeCl2-tBuNH2 reaction and X-ray structures of Se3(NtBu)3, tBuNSe(mu-NtBu)2SO2, and tBuNSe(mu-NtBu)2SeO.

The reaction of SeCl2 with tert-butylamine in various molar ratios in THF at -78 degrees C has been investigated by 77Se NMR spectroscopy. In addition to the known Se-N heterocycles Se6(NtBu)2 (1) and Se9(NtBu)6 (2), the acyclic imidoselenium(II) dichlorides ClSe[N(tBu)Se]nCl (4, n = 1; 5, n = 2) and two new cyclic selenium imides [Se3(NtBu)2]n (3, n = 1 or 2) and Se3(NtBu)3 (6) have been isolated and identified. An X-ray analysis shows that 6 is a six-membered ring in a chair conformation with magnitude of d(Se-N) = 1.833 A. Crystal data: 6, trigonal, P3c1, a = 9.8660(3) A, c = 20.8427(7) A, V = 1757.0(1) A3, Z = 6. The 1H, 13C, and 77Se NMR data for 1-6 are reported, and some reassignments of earlier literature data for 1-3 (n = 1) are made. The decomposition of tBuN=Se=NtBu at 20 degrees C in toluene was monitored by 77Se NMR. The major products are 6 and 3. The Se(IV)-N systems tBuNSe(mu-NtBu)2E (7, E = SO2; 8, E = SeO) were prepared by the reaction of a mixture of SeCl4 and excess tBuNH2 with SO2Cl2 or SeOCl2, respectively. Compound 8 is also generated by the cycloaddition reaction of tBuNSeNtBu with tBuNSeO. Both 7 and 8 consist of slightly puckered four-membered rings. The mean terminal and bridging Se-N distances in 7 are 1.665(2) and 1.948(2) A, respectively. The corresponding values for 8 are 1.687(4) and 1.900(4) A, and d(Se=O) = 1.628(4) A. Crystal data: 7, monoclinic, P2(1)/c, a = 18.669(4) A, b = 12.329(2) A, c = 16.463(3) A, beta = 115.56(3) degrees, V = 3418.4(11) A3, Z = 4; 8, triclinic, P1, a = 6.372(1) A, b = 9.926(2) A, c = 14.034(3) A, alpha = 99.320(3) A, beta = 95.764(3) A, gamma = 103.876(3) A, V = 841.3(3) A3, Z = 2.

A 13C, 15N and 77Se Nmr Study of Some Diseleno Sulfonamides

13C, 15N and 77Se NMR data are reported for ten title compounds. Some linear correlations of selenium, nitrogen and carbon chemical shifts values are described. A number of one- and two- bond 77Se-13C coupling constants values are also given.

Metal complexes of P(Ph 2)CH 2(Ph 2)PSe. Crystal structure of [Ni{P(Ph 2)CH 2(Ph 2)PSe} 2]Cl 2·2EtOH

The reactions of P(Ph 2)CH 2(Ph 2)PSe (dppmSe) with MCl 2 species (M = Ni, Co or Pd) and with [{M′(COD)Cl} 2] complexes (M′ = Rh or Ir) afford mononuclear cationic complexes of the type [M(dppmSe- P,Se) 2]Cl 2 and [M′(COD)(dppmSe- P,Se) 2]Cl. The crystal structure of the nickel derivative has been solved by X-ray diffraction methods. It consists of square planar complex cations, chloride ions and ethanol molecules held together by a network of hydrogen bonds involving also carbon atoms. The chelating behaviour of dppmSe ligand in the Rh and Ir complexes is indicated by 31P and 77Se NMR data. In the case of CuCl 2 a redox process takes place yielding [Cu(dppmSe)Cl], which undergoes air oxidation to give [Cu II{Cu ICl 2[μ-SeC(Ph 2PO) 2]} 2].

The Reaction of Potassium Polyselenides with [CpW(CO)3Cl] in DMF - Formation and Crystal Structure of [CpW(CO)3SeC(O)NMe2] and {[CpW(CO)3]2Se4}

The reactions of the potassium polyselenides „K2Se6” and „K2Se8” with [CpW(CO)3Cl] and 18-crown-6 in DMF lead to a mixture of the selenido complexes {[CpW(CO)3]2Se4} 1 and [(18-crown-6)K]+[CpW(Se4)2]−3 and the Se−bonded selenocarbamato complex [CpW(CO)3SeC(O)NMe2] 2 in yields depending on the selenium content of the used potassium polyselenides („K2Se6” or „K2Se8”). A similar reaction in THF produces {[CpW(CO)3]2Se4} as the main product. X-ray structures of 1 and 2 were determined. In 1 the Se4-chain is bonded in a μ2-η1 fashion, with corresponding W−Se bond lengths of 264.0(1) and 264.3(1) pm. The Se−Se bond lengths lie in the range 232 to 237 pm. The first example of an η1 Se-bonded selenocarbamato ligand is observed in the crystal structure of 2, with a W−Se bond length of 263.1(1) pm. The 77Se-NMR data are compared with the corresponding data of related complexes.

A 13C, 15N and 77Se NMR Study of Some Diseleno Sulfonamides

13C, 15N and 77Se NMR data are reported for ten title compounds. Some linear correlations of selenium, nitrogen and carbon chemical shifts values are described. A number of one- and two- bond 77Se-13C coupling constants values are also given.

Organoselenido Complexes of Tungsten

Organometallic tungsten selenido complexes of the type [cpW(CO)3]2Sem; m = 2 (1), 3 (2), 4 (3), can be easily synthesized via insertion of selenium into the alkali-metal tungsten bond of LiWcp(CO)3 in appropriate ratios and subsequent oxidation of the produced W-selenolates with O2/SiO2. In contrast, reactions of K2Se6 with [cpW(CO)3Cl] and 18-crown-6 in DMF lead to a mixture óf [cpW(CO)3]2Se4 (3), the η1 Se-bonded selenocarbamato complex [cpW(CO)3SeC(O)NMe2] (4) and the ionic complex [(18-crown-6)K]+[cpW(Se4)2]− (5). The crystal structures of 3 and 4 together with their 77Se NMR data are presented.

Selenium-77 NMR studies of cyclopentadienylchromium selenium species. Evidence of conformers

Variable-temperature 77Se NMR spectroscopic studies of the complexes [CpCr(CO) 2] 2Se ( 1) and [CpCr(CO) 2] 2Se 2 ( 2) have been carried out. A singlet 77Se resonance is found for 1 at 213–296K, but the broadness at the higher temperatures suggests the existence of rotamers exchanging at an intermediate rate on the time scale of Δδ Se. For 2, the observations point to the existence of two conformers over the range 213–330 K, with relative proportions varying from ca. 1:3.4 at 320 K to ca. 1:6.4 at 213 K. This conclusion is supported by 13C NMR spectra at 213 and 298 K. Also reported are 77Se NMR data for Cp 2Cr 2(CO) 5Se 2 ( 3), produced in situ by thermolysis of 2 in solution, and solid-state CP-MAS 13C and 77Se NMR data for [CpCrSe] 4 ( 4).