(
E
)-3-(1-Benzofuran-2-yl)propenoic acid (
1
) was prepared from 1-benzofuran-2-carbaldehyde under the Doebner’s conditions. The obtained acid was converted to the corresponding azide
2
, which was ...cyclized by heating in diphenyl ether to 1benzofuro3,2-
c
pyridine-1(2
H
)-one (
3
). This compound was aromatized with phosphorus oxychloride to chloroderivative
4
which was reduced with zinc and acetic acid to the title compound
5
. 1Benzofuro3,2-
c
pyridine-2-oxide (
6
) was synthesized by reaction of
5
with 3-chloroperoxybenzoic acid in dichloromethane. Treatment of
6
with benzoyl chloride and potassium cyanide (Reissert-Henze reaction) was shown to produce the corresponding 1benzofuro3,2-
c
pyridine-1-carbonitrile (
7
). The title compound was used for preparation of complexes Cu
2
(ac)
4
(bfp)
2
(
8
) and CoCl
2
(bfp)
2
(
9
), where ac=CH
3
CO
2
−
and bfp=1benzofuro3,2-cpyridine. Both oxygen atom of carboxylate ions is used in the coordination to Cu(II). Thermal properties of the complexes
8
and
9
have been studied by TG and DTA and both complexes exhibited high thermal stability while complex
9
are thermally more stable than complex
8
.
Four sixcoordinate cobalt(II) complexes of the Co(LN)2(car)2(H2O)2 type have been prepared and structurally characterized. Magnetic susceptibility and magnetization data were analyzed in terms of the ...spin Hamiltonian. D-Parameter adopts values between 80 and 103cm−1. The crystal-field theory analysis of the electronic spectra provided assignments for characteristic absorption bands in the visible region. Obtained crystal-field parameters were used for reconstruction of the magnetic parameters. The results are in good agreement with available experimental data. Display omitted
► Carboxylato cobalt(II) complexes with fused N-heterocycles were studied. ► Large zero-field splitting D-parameters were detected (up to 103cm−1). ► Magnetic parameters were reconstructed from spectral data. ► Usefulness of the crystal-field ZFS models for Co(II) complexes was confirmed.
Heteroleptic cobalt(II) complexes with general formula of Co(N-base)2(car)2(H2O)2, have been synthesized and structurally characterized; the N-base stands for neutral N-donor ligands: iso-quinoline (iqu), 1benzofuro3,2-cpyridine (bzfupy), 1-(pyridin-3-yl)1benzofuro3,2-cpyridine (1-py-bzfupy) and 1-phenyl-1H-imidazole (bylim); car=acetato (ac) or benzoato (bz) ligands. The structure of Co(iqu)2(ac)2(H2O)2 1, Co(bzfupy)2(ac)2·(H2O)2 2, Co(1-py-bzfupy)2(ac)2(H2O)2·H2O 3 and Co(bylim)2(bz)2(H2O)2 4 complexes is formed of the {CoN2O2O2′} chromophore. These complexes were subjected to magnetochemical investigation down to 2K (susceptibility and magnetization measurements). They show magnetic behavior typical for the zero-field splitting systems. The axial parameter of the zero-field splitting adopts large values, D=80–103cm−1. We have analyzed electronic spectra of the complexes in detail with aim to extract the crystal-field parameters. These have been used for reconstruction of the magnetic parameters. The calculated axial ZFS parameters are in good agreement with the experimental values.
The Knoevenagel condensations of 5-3-(trifluoromethyl)phenylfuran-2-carbaldehyde with seven compounds containing an active methyl or methylene group have been studied. The compounds used were: methyl ...2-cyanoacetate, malononitrile, 2-furylacetonitrile, acetophenone, 2-thioxo-1,3-thiazolidin-4-one (rhodanine), 5,5-dimethylcyclohexane-1,3-dione (dimedone), and methyl 2-azidoacetate. The effect of microwave irradiation on the condensation reactions was studied and compared with “’classical”’ conditions. Thermolysis of methyl 2-azido-3-{5-3-(trifluoromethyl)phenyl-2-furyl}propenoate afforded methyl 2-3-(trifluoromethyl)phenyl)-4H-furo3,2-bpyrrole-5-carboxylate. (2E)-3-{ 5-3-(Trifluoromethyl)phenyl-2-furyl}propenoic acid was converted to the corresponding azide, which was cyclized on heating into 2-3-(trifluoromethyl)phenyl)-4,5-dihydrofuro3,2-cpyridin-4-one. The latter after successive action of POCl3 and NH2NH2-Pd/C gave 2-3-(trifluoromethyl)-phenylfuro3,2-cpyridine.
Substituted hydrazones
5
and
6
were synthesized by the reaction of the corresponding furo3,2-
b
pyrrole-5-carboxyhydrazides
1
with 6-substituted 4-oxochromene-3-carbaldehydes
2
and methyl ...2-formylfuro3,2-
b
pyrrole-5-carboxylates
3
under microwave irradiation as well as by the classical method. The beneficial effect of the microwave irradiation on these reactions was a shortening of the reaction time and an increase in the yields. The reactions of
1
with 4-(4-oxochromen-3-yl)methylidene-2-phenyloxazol-5(4
H
)-one (
4
) were also studied. Compounds
7
or
8
were obtained, depending on the reaction temperature.
The nickel(II) complexes Ni(L
n
)
4 (NCS)
2, where L
1
=
furo3,2-
cpyridine, L
2
=
2-methylfuro3,2-
cpyridine, L
3
=
2,3-dimethylfuro3,2-
cpyridine, L
4
=
benzo4,5furo3,2-
cpyridine and L
5
=
...isoquinoline, have been prepared and characterized by structural, spectroscopic and magnetic methods. The structures of the all complexes are formed by isolated molecules. The Ni(II) ions are six-coordinate, the equatorial planes are formed by four N-donor heterocycles whereas the isothiocyanate groups coordinate in the axial positions. The magnetism of the complexes exhibits a zero-field splitting, the magnitude of which correlates with the distortion degree of the coordination polyhedra.
Nickel(II) complexes of the formula Ni(L
n
)
4(NCS)
2, (where L
n
are derivatives of furo3,2-
cpyridine, L
1
=
furo3,2-
cpyridine, L
2
=
2-methylfuro3,2-
cpyridine, L
3
=
2,3-dimethylfuro3,2-
cpyridine and L
4
=
benzo4,5furo3,2-
cpyridine) have been prepared and characterized by spectroscopic methods and magnetic measurements. For comparative reasons, L
5
=
isoquinoline has also been involved. The crystal and molecular structures of Ni(L
2)
4(NCS)
2, Ni(L
4)
4(NCS)
2 and Ni(L
5)
4(NCS)
2 have been determined by X-ray diffractions methods. The structures of all the complexes are formed by isolated molecules. The Ni(II) ions are six-coordinate, the equatorial planes are formed by four N-donor furopyridines whereas the isothiocyanate groups coordinate in the axial positions. The magnetism of the complexes exhibits a zero-field splitting, the magnitude of which correlates with the distortion degree of the coordination polyhedra.
Two furopyridine complexes of nickel(II) isothiocyanate MIKLOVIC, Jozef; KRUTOSIKOVA, Alzbeta; BARAN, Peter
Acta crystallographica. Section C, Crystal structure communications,
05/2004, Letnik:
60, Številka:
Pt 5
Journal Article
Recenzirano
Pyridine fused with a furan ring (fupy), and its dimethyl derivative, have been used for the first time as ligands to synthesize potentially new Werner clathrates. The extended aromatic system of ...pyridine-like ligands influences considerably the molecular structure of prepared nickel complexes. The molecular structure of tetrakis(furo3,2-cpyridine)bis(isothiocyanato)nickel(II) tetrahydrofuran (THF) solvate, Ni(NCS)(2)(C(7)H(5)NO)(4).C(4)H(8)O or Ni(NCS)(2)(fupy)(4).THF, (I), reveals a 'four-blade propeller' arrangement of ligands, with the angles between the fupy planes and the basal octahedron plane spanning the range 38.7-55.3 degrees. These angles are much larger (69.9-78.8 degrees ) in the centrosymmetric complex tetrakis(2,3-dimethylfuro3,2-cpyridine)bis(isothiocyanato)nickel(II) 6.6-hydrate, Ni(NCS)(2)(C(9)H(9)NO)(4).6.6H(2)O or Ni(NCS)(2)(Me(2)fupy)(4).6.6H(2)O, (II), in which crystallographically imposed inversion symmetry is present.
4-Heteroarylidene-2-phenyl-1,3-oxazol-5(4H)-ones were prepared by reactions of hippuric acid with substituted furan-2-carboxaldehydes or furobpyrrole type aldehydes. The reactivity of various ...furan-2-carboxaldehyde derivatives in this reaction is discussed. The effect of microwave irradiation on some condensation reactions was compared with "classical" conditions. The results show that microwave irradiation shortens the reaction times while affording comparable yields. Elementary analysis, UV, IR and 1D NMR proved the structure of new synthesised compounds. 2D NMR spectroscopic measurements confirmed that the configuration at the carbon-carbon double bond corresponds to the pure E isomers of the products.
A series of new push-pull compounds were synthesised by reaction of 5-aryl- furan-2-carboxaldehydes and furobpyrrole type aldehydes with benzothiazolium salts. These new condensation products ...represent highly conjugated systems that have potential biological activity. The reaction of furobpyrrole type aldehydes with benzothiazolium salts give potential precursors of cyanine dyes.
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