Rostislav D. Lampeka

Nickel(II) and tridentate 8-hydroxyquinoline-2-carbaldehyde-N-methylnitrone (HL): enantioselective association of octahedral [M(HL)(L)]+ moieties driven by strong hydrogen bonding

Abstract The novel organic tridentate ligand, 8-hydroxyquinoline-2-carbaldehyde- N -methylnitrone (HL), has been synthesized and used for the design of a metal–organic system capable of self-association. Interaction of the nitrone HL with nickel nitrate afforded the hydrogen nitronate complex [Ni(HL)(L)] 2 (NO 3 ) 2 ·7H 2 O, which was characterized by means of X-ray diffraction. The coordination environment of the metal atoms consists of four oxygen and two nitrogen atoms from neutral and anionic forms of the ligand. [Ni(HL)(L)] + cations possess a set of self-complementary H-bond donor/acceptor sites and dimerize via strong hydrogen bonding (O⋯O 2.43, 2.45 A) forming supramolecular dications [Ni(HL)(L)] 2 2+ . Dimerization occurs enantioselectively between [Ni(HL)(L)] + moieties of the same chirality and the resulting dimeric ensemble is inherently chiral. The stability of the dimer is essentially influenced by stacking interactions between two pairs of aromatic frames.

Metallkomplexe mit biologisch wichtigen Liganden, LXIX [1].

(η5-C5Me5) (M - Co, Rh, Ir) and (η5-p-cymene)(CI) have been obtained by reactions of (η5-C5Me5)Co(CO)I2, [(η5-C5Me5)MCl2]2 (M = Rh, Ir) and [(η6-p-cymene)RuCl2]2 with 2-hydroxyiminocarboxylates. These complexes are also accessible by template synthesis from hydroxylamine or O-methylhydroxylamine, α-oxocarboxylate and (η5-C5Me5)Co(CO)I2 or [(η5-C5Me5)MCl2]2 (M = Rh, Ir). The structure of the SRu enantiomer of (η5-C5Me5)(I) has been determined by X-ray diffraction.

Metallkomplexe mit biologisch wichtigen Liganden, LXXII [1]. Halbsandwichkomplexe von Iridium(III) und Ruthenium(II) mit Dianionen von 2-Hydroxyiminocarbonsäuren / Metal Complexes of Biologically Important Ligands, LXXII [1]. Half Sandwich Iridium(III) and Ruthenium(II) Complexes with Dianions of 2-Hydroxyiminocarboxylic Acids

Chiral chelate complexes with dianions of 2-hydroxyiminocarboxylic acids (1) und (2) are obtained by deprotonation of the compounds and in the presence of a donor ligand (Do=PR3, P(OMe)3, py). The structure of has been determined by X-ray diffraction.

Nucleophilic Additions of Methanol to the Dichloropalladium(II) Complex with C-(2-Pyridyl)-N-methylnitrone

The additions of methanol to the dichloropalladium(II) complex with C-(2-pyridyl)-Nmethylnitrone led to the formation of the Pd(II)-coordinated α-methoxy-α-(2-pyridyl)-N,Ndimethylhydroxylamine. It has been demonstrated that the Pd(II) complexation is essential for the stabilization of α-alkoxyhydroxylamines.

New Coordination Compounds Derived from Nitrone Ligands: Copper(II) Complexes with 8-Hydroxyquinoline-2-carbaldehyde- and Pyridine-2-carbaldehyde-N-methylnitrones

Abstract New copper(II) complexes with 8-hydroxyquinoline-2-carbaldehyde-N-methylnitrone (HL1) (1) and pyridine-2-carbaldehyde-N-methylnitrone (L2) (2) have been synthesized. The crystal structure of compound 1 consists of binuclear molecules Cu2(L1)2(NO3)2 with the oxygen atoms of the hydroxy groups acting as bridges between the copper ions. The nitrone ligand in 1 is coordinated in a tridentate fashion forming five-and six-membered chelate rings, and the copper ions have a square-pyramidal environment with the bridging oxygen atoms in apical positions. In compound 2 Cu(L2)2(NO3)2, the copper atom adopts a distorted octahedral environment with bidentately coordinated nitrone ligands. In both cases the nitrone groups are involved in coordination via the oxygen atom. Compounds 1 and 2 have been studied by EPR, UV-VIS and IR spectroscopy. The free nitrone HL1 has also been studied by X-ray diffraction as well as by IR and UV spectroscopy.

Synthesis, solution and solid-state structure of Pd(II), Pt(II), Ir(III) and Zn(II) complexes with 5-pyridyl substituted N-methyl isoxazolidines

Abstract Pd(II), Pt(II), Zn(II) and Ir(III) complexes with 5-pyridine substituted N-methyl isoxazolidines (4-(2-methyl-3-phenylisoxazolidin-5-yl)-pyridine (L1), 2-(2-methyl-3-phenylisoxazolidin-5-yl)-pyridine (L2), 2-(2-methyl-3-ferrocenylisoxazolidin-5-yl)-pyridine (L3)) have been prepared and characterized by 1H, 13C, and 31P NMR. The configurations of coordinated isoxazolidines have been assigned by the analysis of NMR coupling constants and by nuclear Overhauser measurements through 2D-ROESY experiments. The molecular structures of [Cp*Ir(L2)Cl][BPh4] (6) (Cp*-pentamethylcyclopentadienyl) and trans-[PdCl2(L3)PEt3] (8) have been established by means of X-ray crystallography. The crystal structure of 6 consists of piano stool geometry with respect to the Ir(III) center with N,N-bidentate coordinated ligands. The six-membered chelate ring formed by Ir(1), N(1), C(5), C(6), O(1), N(2) possesses a ‘twist-tub’ conformation. The crystal structure of 8 consists of neutral square planar Pd(II) complexes. L3 is coordinated in a monodentate manner via the pyridine nitrogen atom. The isoxazolidine fragment of both compounds has an envelope conformation. NMR data are consistent with an O,N-bidentate coordination of L2 for [Zn(L2)Cl2] (5), while L1 act as a monodentate ligand through the nitrogen atom of the pyridine in [Zn(L1)2Cl2] (4).

2-Oximinocarboxylates of certain metals and their antiviral activity

6. 7. 8. LITERATURE CITED V. S. Arutyunyan, L. O. Rostomyan, and M. G. Zalinyan, Arm. Khim. Zh., 34, No. ii, 958 (1981) . S. M. Gabrielyan, L. O. Rostomyan, A. G. Khachikyan, et al., Chemistry and Chemical Technology [in Russian], No. 2, Erevan (1983), p. 112. G. Deison and P. May, Chemistry of Synthetic Drugs [Russian translation], Moscow (1964) . M. G. Zalinyan, G. G. Danagulyan, N. G. Balasanyan, et al., Arm. Khim. Zh., 41, No. 5, 282 (1988) . M. Asano, K. Takahashi , T. Muracami, e t a l . , J . Pharm. Soc. Jpn . , 70, 202; Chem. Abs t r . 4__44, 7229d (1950) . D. E. Genge and J . a. T r i v e d i , a. Ind ian Chem. Soc . , 37, No. 8, a29 (1960). W. F. Oe t t ingen and F. Garc ia , a. Pharmacol . , 36~ 355 (1929). V. I . Votyakov, E. I . goreko, and g. V. Vladyko, Primary I n v e s t i g a t i o n of A n t i v i r a l P r o p e r t i e s of S y n t h e t i c and Na tura l Compounds [ in Russ i an ] , Minsk (1986).

Complexation of 3-(2-pyridyl)substituted N-methyl isoxazolidine with Pd(II), Zn(II) and Cu(II): stereochemistry of co-ordination compounds in solution and solid-state

2-Methyl-3-(2-pyridyl)isoxazolidine ( L ) and its Pd(II), Zn(II) and Cu(II) complexes have been prepared and characterized by IR, 1 H, 13 C 1D and HMBC, NOESY 2D NMR spectroscopies. The stereochemistry of the ‘free’ and co-ordinated ligand has been assigned by nuclear Overhauser effect (NOE). The molecular structures of [Zn( cis - L )Cl 2 ]·0.5CHCl 3 ( 2a ), [Zn( cis -/ trans - L )Cl 2 ] ( 2a – b ) and [Cu( cis -/ trans - L )Cl 2 ] 2 ( 4a – b ) have been established by means of X-ray crystallography. The crystal structure of 2a consists of a racemic mixture of cis - L (3 SR ,5 RS ), while the crystal structure of 2b comprises a racemate of cis - and trans -isomeric forms. For both complexes the zinc atoms adopt nearly tetrahedral co-ordination with two chlorine atoms and N , N -bidentate co-ordinated L . The crystal structure of 4a – b consists of dinuclear [Cu( cis -/ trans - L )Cl 2 ] 2 moieties with N , N -bidentate co-ordinated ligands. The square pyramidal co-ordination spheres of copper ions are completed by a bridging chloride ligand at the apex (CuCl 2.79, 2.82 A).

Synthesis and crystal structure of cobalt(II) and copper(II) complexes of 3,3′-biisoxazolidines as chelating ligands

AbsractNew mononuclear Cu(II) and Co(II) complexes [Cu{L1}(NO3)2]·H2O (1) and [Co{L2}(H2O)3)](NO3)2 (2), with conformationally flexible isoxazolidine ligands, namely 3,3′-bi{2-methyl-5-phenyl}isoxazolidine (L1) and 3,3′-bi{2-methyl-5-pyridyl}isoxazolidine (L2), were synthesized and characterized. X-ray crystallographical analysis reveals that the Cu(II) atoms adopt a distorted octahedral environment. The ligand L1 forms five-membered chelates via the isoxazolidine nitrogen atoms. The Co(II) atom in 2 is in a distorted octahedral geometry. The ligand L2 coordinates the metal center with formation of two chelate rings, involving donors of two isoxazolidine and pyridyl groups. In the complex cation, three donor atoms of the ligand occupy the MN3 facial positions.

Synthesis and Structure of a Palladium(II) Chloride Complex with 2-(2-Methyl-3-phenyl-isoxazolidin-5-yl)-pyridine

The 1:1 complex of palladium(II) chloride with 2-(2-methyl-3-phenyl-isoxazolidin-5-yl)- pyridine (L) has been prepared and studied by means of elemental analysis, 1H NMR spectroscopy and X-ray diffraction (monoclinic, space group P21/n with parameters: a = 8.141(2), b = 9.750(2),c = 20.691(6)Å ,β = 95.62(3)°,V = 1634.4(7)Å3 ,Z = 4 ;R1= 0.054 and wR2= 0.144 for 3352 unique reflections). A square-planar coordination polyhedron has been established for the palladium atom both in acetone solution and in the solid state. The organic ligand is coordinated toometal in a bidentate manner via nitrogen atoms of the pyridine substituent (Pd-N(2) 2.125(3) Å) and the isoxazolidine heterocycle (Pd-N(l) 2.102(3) Å). The other two coordination positions of palladium are occupied by chlorine atoms (Pd-Cl(l) 2.321(1) and Pd-Cl(2) 2.333(1) Å). The six-membered chelate ring formed by Pd, N(2), C(4), C(1), 0(1) and N (1) possesses a “twist-tub” conformation. The isoxazolidine cycle has an envelope conformation with an equatorial orientation of the methyl group.