Selenocyanate Research Articles

Dynamics in a Room-Temperature Ionic Liquid from the Cation Perspective: 2D IR Vibrational Echo Spectroscopy.

The dynamics of the room-temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimNTf2) were investigated with two-dimensional infrared (2D IR) vibrational echo spectroscopy and polarization selective pump-probe (PSPP) experiments. The CN stretch frequency of a modified Bmim+ cation (2-SeCN-Bmim+), in which a SeCN moiety was substituted onto the C-2 position of the imidazolium ring, was used as a vibrational probe. A major result of the 2D IR experiments is the observation of a long time scale structural spectral diffusion component of 600 ps in addition to short and intermediate time scales similar to those measured for selenocyanate anion (SeCN-) dissolved in BmimNTf2. In contrast to 2-SeCN-Bmim+, SeCN- samples its inhomogeneous line width nearly an order of magnitude faster than the complete structural randomization time of neat BmimNTf2 liquid (870 ± 20 ps) measured with optical heterodyne-detected optical Kerr effect (OHD-OKE) experiments. The orientational correlation function obtained from PSPP experiments on 2-SeCN-Bmim+ exhibits two periods of restricted angular diffusion (wobbling-in-a-cone) followed by complete orientational randomization on a time scale of 900 ± 20 ps, significantly slower than observed for SeCN- but identical within experimental error to the complete structural randomization time of BmimNTf2. The experiments indicate that 2-SeCN-Bmim+ is sensitive to local motions of the ionic region that influence the spectral diffusion and reorientation of small, anionic, and neutral molecules as well as significantly slower, longer-range fluctuations that are responsible for complete randomization of the liquid structure.

Nucleophilic displacement reactions of 5'-derivatised nucleosides in a vibration ball mill.

Vibration ball-milling in a zirconia-lined vessel afforded clean and quantitative nucleophilic displacement reactions between 4-methoxybenzylthiolate salts and nucleoside 5′-halides or 5′-tosylates in five to 60 minutes. Under these conditions, commonly-encountered nucleoside cyclisation byproducts (especially of purine nucleosides) were not observed. Liquid-assisted grinding of the same 5'-iodide and 5′-tosylate substrates with potassium selenocyanate in the presence of DMF produced the corresponding 5′-selenocyanates in variable yields over the course of between one and eleven hours thereby avoiding the preparation and use of hygroscopic tetrabutylammonium salts.

ChemInform Abstract: A New Heterocycle: Furo[3,2‐c]isoselenazole.

AbstractPreviously undescribed isoselenazoles (II) are obtained by a simple domino process in one synthetic operation from malononitriles (I) with potassium selenocyanate.

A one-pot synthesis of 2H-pyrido[1,2-a][1,3,5]triazine-2-selenones from acyl isoselenocyanates and pyridin-2-amine

Acyl isoselenocyanates, prepared by acyl chlorides and potassium selenocyanate, are trapped by pyridin-2-amine to afford 4-substituted pyrido[1,2-a][1,3,5]triazine-2-selenone in moderate to good yields.

A Novel Synthesis of Highly Functionalized 1,2,4-Diselenazolidines from Acyl Isoselenocyanates

A simple one-pot synthesis of highly functionalized 1,2,4-diselenazolidines is described. Treatment of an acyl chloride with potassium selenocyanate in acetone gave an acyl isoselenocyanate and propane-2-selone, which both reacted with benzylamine or its derivatives to give the required products.

ChemInform Abstract: Trifluoromethylselenolation of Aryldiazonium Salts: A Mild and Convenient Copper‐Catalyzed Procedure for the Introduction of the SeCF3 Group.

AbstractA highly efficient two‐step one‐pot approach to the desired products is developed which proceeds via formation of selenocyanates.

A new heterocycle: furo[3,2-c]isoselenazole

New heterocycles, furo[3,2-c]isoselenazoles, were obtained by the reaction of 2-[amino(2-cyano-3-aryloxiran-2-yl)methylene]malononitriles with potassium selenocyanate.

Trifluoromethylselenolation of Aryldiazonium Salts: A Mild and Convenient Copper-Catalyzed Procedure for the Introduction of the SeCF3 Group.

The straightforward introduction of the trifluoromethylseleno group into aromatic and heteroaromatic compounds is accomplished by the utilization of readily available aryldiazonium tetrafluoroborates, potassium selenocyanate, and Ruppert-Prakash reagent. The reaction tolerates a wide range of aromatic and heteroaromatic diazonium salts and is also amenable to the synthesis of pentafluoroethyl selenoethers. Furthermore, the methodology can be applied directly starting from anilines.

Synthesis, crystal structure, solid state electronic spectra and thermal study of three cobalt(II)–selenocyanate complexes: In situ room temperature transformation of 4,4′-dipyridyldisulfide to 4,4′-dipyridylsulfide

Three new supramolecular networks of cobalt(II), [Co(phen)2(SeCN)2] (1), [Co(bpe)2(SeCN)2]n (2), and {[Co(bps)2(SeCN)2]·H2O}n (3) [phen=1,10-phenanthroline; bpe=1,2-bis(4-pyridyl)ethane; bps=4,4-bipyridylsulfide] have been synthesized and characterized by X-ray single crystal structure determination, solid state electronic spectroscopy and thermogravimetric analysis. Complex 1 is a neutral discrete cobalt(II) complex with cis located selenocyanate anions and forms 2D supramolecular layers through π−π interactions. Complexes 2 and 3 have a comparable structure based on metal center bridged by two bpe or bps ligands trough pyridinyl N-donor to give rise to a linear chain. The selenocyanate anions (SeCN−) bind the metal centers through nitrogen and occupy trans axial positions of the octahedral metal coordination environment. These pendant pseudohalides located on both sides of the 1D polymeric chain help to reinforce the packing through weak interactions. Solid state electronic spectra of all the complexes corroborate the presence of octahedral high spin cobalt(II) centers in all complexes.

Synthesis, chemical characterization, DNA interaction and antioxidant studies of ortho, meta and para fluoro substituted ferrocene incorporated selenoureas

We have reported a one pot synthesis of three new ferrocene incorporated selenoureas namely; 1-(2-fluorobenzoyl)-3-(4-ferrocenyl-3-methylphenyl)selenourea (MeP2F), 1-(3-fluorobenzoyl)-3-(4-ferrocenyl-3-methylphenyl)selenourea (MeP3F) and 1-(4-fluorobenzoyl)-3-(4-ferrocenyl-3-methylphenyl)selenourea (MeP2F) by the reaction of corresponding carboxylic acid chlorides with potassium selenocyanate (KSeCN) and 3-methyl-4-ferrocenyl aniline in acetone under constant stirring. Synthesized compounds were characterized by FTIR, NMR (1H and 13C), CHNS and AAS. We have also presented X-rays single crystal structure for MeP2F. DNA binding studies were evaluated with the help of cyclic voltammetry in the presence of TBAP (tertiary butyl ammonium perchlorate) as supporting electrolyte in DMSO/water mixture of 70:30. Binding constant for MeP2F is 1.499 ×103M−1, MeP3F is 1.706 ×103M−1 and MeP4F is 1.035×103M−1. Binding site size for MeP2F (0.334bp)<MeP4F (0.410bp)<MeP3F (0.463bp). In all the compounds diffusion coefficients of drug-DNA adduct is lower than the free drug indicating slow diffusion of comparatively high molecular weight drug towards the electrode in cyclic voltammetry. Mode of interaction has further been reconfirmed with the help of viscometry. All the three compounds have good antioxidant activities against DPPH with IC50 values of 132, 108 and 84μg/ml for MeP2F, MeP4F and MeP3F respectively.

Catena-Poly[[[bis(methanol-κO)bis(selenocyanato-κN)manganese(II)]-μ-1,2-bis(pyridin-4-yl)ethane-κ2N:N′] 1,2-bis(pyridin-4-yl)ethane monosolvate

The reaction of manganese seleno­cyanate with 1,2-bis­(pyridin-4-yl)ethane (bpa) leads to the title compound, {[Mn(NCSe)2(C12H12N2)(CH3OH)2]·C12H12N2}n. The MnII cation is coordinated by two N-bonded seleno­cyanate anions, two bpa ligands and two O-bonded methanol mol­ecules, within a slightly distorted octa­hedral geometry. The MnII cations and the non-coordinating N-donor ligands are located on centers of inversion while the coordinating N-donor co-ligands are located on a twofold rotation axis. In the crystal, the MnII cations are linked into chains along the c-axis direction by the bpa ligands. The chains are further connected via a non-coordinating bpa ligand into layers parallel to (3-10) via O—H⋯N hydrogen-bonding inter­actions.

Influence of supramolecular bonding contacts on the spin crossover behaviour of iron(ii) complexes from 2,2′-dipyridylamino/s-triazine ligands

Reactions of the related ligands 2-(N,N-bis(2-pyridyl)amino)-4,6-bis(phenoxy)-(1,3,5)triazine (L1) and 2-(N,N-bis(2-pyridyl)amino)-4,6-bis(pentafluorophenoxy)-(1,3,5)triazine (L1(F)) with iron(II) thiocyanate produced two spin-crossover coordination compounds with distinct cooperative behaviours. trans-[Fe(L1)2(NCS)2]·2CH2Cl2 (1) displays a very gradual transition centred at T½ = 233 K, characterized by a ΔT80 (namely the temperature range within which 80% of the transition considered occurs) of 90 K, while that of fluorinated trans-[Fe(L1(F))2(NCS)2]·2CH3CN (3) is significantly more abrupt (and centred at T½ = 238 K), with a ΔT80 of 50 K, resulting from supramolecular contacts induced by the fluorinated phenol groups. The coordination compound equivalent to 1 with selenocyanate anions, namely trans-[Fe(L1)2(NCSe)2]·4CH2Cl2·4CH3OH (2), also exhibits SCO properties centred at T½ = 238 K, but the transition is very gradual (ΔT80 = 150 K). Light-induced excited spin-state trapping (LIESST) is effective although incomplete for 2 and 3, while it is complete with a T(LIESST) of 58 K for 1.

Subtlety of the Spin‐Crossover Phenomenon Observed with Dipyridylamino‐Substituted Triazine Ligands

AbstractReactions of the new, closely related ligands 4,6‐dichloro‐N,N‐di(pyridine‐2‐yl)‐1,3,5‐triazine‐amine (Cldpat) and 6‐chloro‐N′‐phenyl‐N,N‐di(pyridin‐2‐yl)‐1,3,5‐triazine‐2,4‐diamine (Cladpat) with iron(II) thiocyanate produced coordination compounds with drastically distinct magnetic properties. The compound trans‐[Fe(Cldpat)2(NCS)2](H2O) (1) is a high‐spin complex from room temperature down to 5 K whereas the analogous compound trans‐[Fe(Cladpat)2(NCS)2] (2) exhibits spin‐crossover (SCO) properties with T1/2 = 178 K. Compounds 1 and 2 (both in its low‐spin and high‐spin states) have been structurally characterized by X‐ray diffraction studies, which revealed identical metal coordination spheres. The SCO properties of 2 have been thoroughly investigated by temperature‐dependent magnetic susceptibility measurements and differential scanning calorimetry (DSC), and a LIESST process with rapid relaxation of the trapped HS species has been observed. The equivalent coordination compound with selenocyanate anions, namely [Fe(Cladpat)2(NCSe)2] (3) also displays SCO properties, although more gradual and with a lower T1/2 value of 166 K.

Reaction with Hydrazonoyl Halides 64: Synthesis of Some New Triazolino[4,3‐a]pyrimidines, 1,3,4‐Thiadiazoles, and 5‐Arylazothiazoles

2,3‐Dihydro‐1,3,4‐thiadiazoles, 2,3‐dihydro‐1,3,4‐selenadiazoles, and triazolino[4,3‐a]pyrimidines containing benzofuran moiety were prepared from the reaction of 2‐(2‐phenylhydrazono)‐1‐(5‐bromobenzofuran‐2‐yl)‐2‐chloroethanone with each of potassium thiocyanate, potassium selenocyanate, alkyl carbodithioate, and pyrmidine‐2‐thione derivatives. All the newly synthesized compounds were confirmed by elemental analysis, spectral data, and alternative route synthesis whenever possible.

Diaquabis[2,6-bis(4H-1,2,4-triazol-4-yl)pyridine-κN2]bis(selenocyanato-κN)cobalt(II)

In the title compound, [Co(NCSe)2(C9H7N7)2(H2O)2], the Co2+ cation is coordinated by two seleno­cyanate anions, two 2,6-bis­(4H-1,2,4-triazol-4-yl)pyridine ligands and two water mol­ecules within a slightly distorted N4O2 octa­hedron. The asymmetric unit consists of one Co2+ cation, which is located on a center of inversion, as well as one seleno­cyanate anion, one 2,6-bis­(4H-1,2,4-triazol-4-yl)pyridine ligand and one water mol­ecule in general positions. Inter­molecular O—H⋯N hydrogen bonds join the complex mol­ecules into layers parallel to the bc plane. The layers are linked by C—H⋯N and C—H⋯Se hydrogen bonds into a three-dimensional supra­molecular architecture.

Tetrakis(pyridazine-κN)bis(selenocyanato-κN)cobalt(II) pyridazine disolvate

Reaction of cobalt(II) nitrate with potassium seleno­cyanate and pyridazine leads to single crystals of the title compound, [Co(NCSe)2(C4H4N2)4]·2C4H4N2, which is isotypic with its nickel(II) thio­cyanate analogue. The Co2+ cations are coordinated by two N-bonded seleno­cyanate ligands and four N atoms from four pyridazine ligands into discrete complexes. The complexes are arranged into layers parallel to (001). These layers are separated by additional non-coordinating pyridazine ligands.

Pseudohalogenido complexes of iron-2,2′-bidipyrrins

The chlorido iron(III) complex of octaethyl-2,2′-bidipyrrin has been transformed to a series of pseudohalide complexes by ligand exchange reactions with azide, cyanate, thiocyanate and selenocyanate anions. All new complexes show the expected N-coordination of the axial ligand to the iron(III) center. In the solid state, all four species display an intermediate spin (S = 3/2) ground state, with a gradual increase of a high spin (S = 5/2) contribution at elevated temperatures for the members with the smallest ligand field strengths, i.e. the cyanato and the azido derivatives. In solution, proton NMR, and in particular IR spectroscopic studies support the interpretation of a high-spin state at ambient temperature throughout the series. The dependency of the spin state on the crystalline or dissolved state thus resembles that found for a similar series of halide derivatives before. In dichloromethane solution, the thiocyanato and selenocyanato complexes are very sensitive to aerial oxidation, forming oxacorrole and thiacorrole complexes as the only isolated products. These complexes show a S = 3/2 spin state in the solid as well as in solution, and their structural analyses prove the expected strong π-binding of the linear pseudohalide ion to the iron(III) central metal.

Catena-Poly[[bis(3-acetylpyridine-κN)cadmium]-di-μ-selenocyanato-κ2N:Se;κ2Se:N

In the crystal structure of the title compound, [Cd(NCSe)2(C7H7NO)2]n, the Cd2+ cation is coordinated by two 3-acetyl­pyridine ligands and four μ-1,3-bridging seleno­cyanate anions within a slightly distorted CdN4Se2 octa­hedron. The asymmetric units consists of one Cd2+ cation, which is situated on a center of inversion, as well as one seleno­cyanate anion and one 3-acetyl­pyridine ligand in general positions. The metal cations are μ-1,3-bridged via the seleno­cyanate anions into chains along the a axis.

ChemInform Abstract: Potassium Selenocyanate as an Efficient Selenium Source in C—Se Cross‐Coupling Catalyzed by Copper Iodide in Water.

AbstractThe novel protocol can be applied best to aryl iodides.

Poly[bis(μ2-pyrimidine-κ2N:N′)bis(selenocyanato-κN)zinc

The asymmetric unit of the title compound, [Zn(NCSe)2(C4H4N2)2]n, consists of one Zn2+ cation located on a special position with site symmetry 2/m, one seleno­cyanate anion on a mirror plane and one pyrimidine ligand on a twofold rotation axis. The zinc cation is coordinated by six N atoms of four pyrimidine ligands and two N-bonded seleno­cyanate anions in mutually trans orientations within a slightly distorted octa­hedral coordination environment. The Zn atoms are μ-1,3-bridged via the pyrimidine ligands into a polymeric layer extending parallel to (100).