V. I. Sokol

Cyclodimerization of bicyclo [2.2.1] hepta-2,5-diene by rhodium carboxylates

Abstract It is shown that the adduct of Rh2(CF3COO)4 with NBD is formed in dichloromethane at room temperature. The addition of an NBD excess to the Rh2(CF3COO)4 solution results in the reduction of Rh(II) to Rh(I). Heating of Rh2(CF3COO)4 either in NBD or in its mixture with benzene (1:3) yields red crystals of [Rh(NBD)CF3COO]2. This compound is the catalyst of NBD cyclodimerization. The selectivity of cyclodimer formation is regulated by the ligand environment of the rhodium atom.

Synthesis of a new aza-14-crown-4 with di(α-pyridyl)-substituted bispidine subunit and the crystal structure of its complex with CoCl2

The aza-14-crown-4 with the di(α-pyridyl)-substituted bispidine subunit (L) and its cationanion complex with cobalt(II) chloride of composition [Co(L)(H2O)][CoCl4] (I) have been synthesized. The structure of compound L has been proved by IR spectroscopy, NMR, and mass spectrometry. X-ray crystallography has demonstrated that the L molecule in the complex is an NNNN-tetradentate chelating ligand, and the crown ether moiety is not directly bound to the metal cation. In the cationic moiety of the complex, the Co(1) atom has an octahedral environment, and the Co(2) polyhedron in the anionic moiety is a tetrahedron. The cationic and anionic moieties of complex I are linked by the bridging chlorine atom.

Synthesis, crystal structure, and spectral studies of 10-(2-Benzothiazolylazo)-9-phenanthrol

Abstract10-(2-Benzothiazolylazo)-9-phenanthrol (L) is prepared by a reaction of 2-hydrazinobenzothiazol with 9,10-phenanthrenequinone. The crystal and molecular structure of the L·CHCl3 solvate is determined by X-ray diffraction. The data of the X-ray diffraction study, as well as IR, 1H NMR, and electronic absorption spectra, indicate that in the crystal state and solutions the L molecule exists in the form of a quinohydrazone tautomer (b) (s-trans, cis) stabilized by the intramolecular N2-HN2…O1 hydrogen bond. The “mobile” H atom is located at the N2 atom of the azo group. The benzothiazolyl and phenanthrenequinone fragments are nearly coplanar. Spectroscopic criteria for the state of L in various media are determined based on the data of IR, 1H NMR, and electronic absorption spectroscopy and the results of the Pariser-Parr-Pople quantum-chemical calculations.

Synthesis, crystal structure, and spectra of 9(E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazone and its cation-anion complex with copper(I) bromide

The reaction of 1-hydrazino-3,3-dimethyl-3,4-dihydroisoquinoline with 9,10-phenanthrenequinone gave (9E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazone (L). The reaction of L with copper(II) bromide gave the complex (LH)[CuBr2]. The crystal structures of the monohydrate L · H2O (I) and the isolated complex (LH)[CuBr2] (II) were determined by X-ray diffraction. The structural units of I are pseudo-centrosymmetric dimers in which the L and water molecules are combined by strong hydrogen bonds. The active H atom is located at the N(1) atom of the isoquinoline fragment of the L molecule. The L molecule occurs in the crystal as the cis, trans isomer with respect to exocyclic C=N bonds at the isoquinoline and phenanthrenequinone fragments, respectively. Complex II has a cation-anion structure. The LH+ cation as the cis, cis isomer is protonated at N(2) and stabilized by two intramolecular hydrogen bonds. In the CuBr2− anion, the copper atom in the oxidation state +1 has a linear coordination, the C-Br bond length is 2.185(4) ± 0.005 Å, and the BrCuBr angle is 179.8(4)°. The main ion-ion interactions in structure II are shortened contacts involving bromine atoms, which combine cations and anions into a three-dimensional framework.

Synthesis, crystal structure, and spectra of the trichloromethane solvate of nickel(II) 9(E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazonate

The complex [Ni(L-H)2] · CHCl3 (I), where L-H is the (9E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazone anion (L), was synthesized for the first time. The crystal structure of I was solved. The L-H and L-H′ anions exist as cis- and trans-isomers and are linked to the central Ni2+ atom in a tridentate chelating mode giving rise to two conjugated five-membered metal rings of different composition (NiN3C and NiONC2) at each anion. The Ni2+ coordination polyhedron is a highly distorted octahedron whose axial positions are occupied by N(3) and N(3)′ atoms. The vertices of the tetrahedrally distorted equatorial base of the octahedron are occupied by the N(1) and N(1)′ atoms of the dihydroisoquinoline fragment (A) and the O(1) and O(1)′ atoms of the phenanthrenequinone fragment (B). Complex I occurs as the cis-isomer. The conformations of the L-H anions in I and the L molecules in L · H2O do not differ much. The randomly disordered CHCl3 solvent molecules in I occupy crystal voids between the centrosymmetric dimeric associates. Spectroscopic (IR and UV-Vis) characteristics of I were obtained.

Synthesis, crystal structure, and spectroscopic studies of 10-(1-phthalazinylazo)-9-phenanthrol (HL). Complexation of cadmium and zinc chlorides with HL

Abstract10-(1-Phthalazinylazo)-9-phenanthrol (HL, I) was synthesized by the reaction between 1-hydrazinophthalazine and 9,10-phenanthrenequinone. The crystal and molecular structures of compound I were determined by X-ray diffraction (XRD). According to XRD, EAS, and 1H and 13C NMR data, a HL molecule in solutions and in crystals exists in the form of quinohydrazone tautomer (b) (s-trans, cis) stabilized by intramolecular N(3)H...O(1) hydrogen bond. The “mobile” H atom is localized at the N(3) atom of the azo group. The phthalazine (A) and phenanthrenequinone (B) moieties of the HL molecule are nearly coplanar. The HL basicity and acidity constants (pKa = 1.90 and pKa = 11.65, respectively) and the formation constants of HL complexes with Zn2+ and Cd2+ and their compositions in solutions were determined. ML2 · DMFA complexes, where M = Zn2+, Cd2+, were synthesized. The coordination mode of the L− ligand with metal atoms was suggested.

Bis(benzo)triazinethionoaza-14-crown-4 ether and its complex with CoBr2: Synthesis and crystal structures

Abstract8,11,14-Trioxa-22,24,25-triazatetracyclo[19.3.1.02,7.015,20]pentacosa-2,4,6,15(20),16,18-hexaene-23-thione (L) containing a symmetric triazinethione subunit in its macrocycle and its complex with cobalt(II) bromide of the formula [CoL2Br2] · 0.5CHCl3 (I) were obtained and examined by X-ray diffraction, IR and NMR spectroscopy, and mass spectrometry. It was found that the thiourea fragment in compound L is attached to the nitrogen macrocycle through the C(2) and C(19) atoms, thus forming a substantially nonplanar six-membered triazine ring in a slightly distorted sofa conformation. Its mean-square plane is nearly perpendicular to the mean-square plane of the macrocycle (the dihedral angle between them is 83.3°). Structure L is stabilized by two bifurcate endocyclic hydrogen bonds between the N(1) atom of the triazine ring and the O(1) and O(3) atoms. The size of the macrocyclic cavity is 4.07 Å. The coordination polyhedron of the Co atom is a distorted tetrahedron made up of the sulfur atoms of two monodentate terminal molecules L and two bromine atoms.

Synthesis of metal complexes with 2-[bis(2-phenylethyl)-thiophophorylhydroxymethyl]-1-organilimidazoles. Crystal structure of ZnCl2 · 2L

The reactions of Zn(II), Cd(II), Cu(II), Co(II), Pd(II) dichlorides with 2-[bis(2-phenylethyl)thiophosphorylhydroxymethyl]-1-organilimidazoles (L1–L4) were studied. The novel complexes were synthesized and characterized by IR and NMR spectroscopies. Depending on the nature of imidazolephosphinesulfide, both monodentate (at the “pyridine” N(1) atom of heterocycle) and the N,S-bidentate binding of the ligand by a metal can be realized in the above metal complexes. The structure of the complex ZnCl2 · 2L4(I) (L4 = 2-[bis(2-phenylethyl)thiophosphorylhydroxymethyl]-1-ethylbenzimidazole) was studied by X-ray diffraction. One of the two independent L4 molecules performs the solvate function, while another one, together with two Cl atoms, is coordinated through the atoms N(1) and S to the Zn atom at the vertices of a slightly distorted tetrahedron. The molecule of the complex is united with the solvate molecule into [ZnCl2L4]L4 associates by strong intermolecular hydrogen bonds to give nonplanar four-membered H-cycle OH2N.

Crystal and Molecular Structure of Bi-1,1′-(3,3-dimethyl-3,4-dihydroisoquinoline)

Bi-1,1′-(3,3-dimethyl-3,4-dihydroisoquinoline) (I) was synthesized. Its crystal structure was determined by X-ray diffraction analysis. Compound I crystallizes as isomer that is intermediate between the syn- and anti-forms with the angle of rotation between the bicyclic fragments equal to 90.1°. The N(1)=C(1) bond length is 1.276(4) ± 0.003 Å.

Synthesis and crystal and molecular structures of new copper and zinc complexes with aza-14-crown-4 ether having di(α-pyridyl)-substituted bispidine subunit

The complexes [Cu(L)(H2O)](ClO4)2 · 2H2O (I) and [Zn(L)Cl2] · C2H5OH (II), where L is the macrocyclic substituted aza-14-crown-4 ether molecule containing di(α-pyridyl)bispidine insert, were synthesized and studied by X-ray diffraction. The Cu atoms in complex I and the Zn atoms in complex II have equal coordination numbers of 5 and different highly distorted polyhedra (the CuN4O tetragonal pyramid and ZnN3Cl2 trigonal bipyramid). Ligand L in structure I performs the tetradentate tetrachelate (4N) structural function and in II, it performs the tridentate bis-chelate (3N) function. The key difference between the structures of complexes I and II is determined by different conformations of both the aza-macrocycles and bispidine substituents of ligand L.