Ion-selective properties of 1,8-bis [2-(dihydroxyphosphinyl)phenoxy]-3,6-dioxaoctane (H4L3), synthesis and vibrational spectra of copper and zinc complexes with H4L3, and crystal and molecular structure of [Cu(H4L3)(H2O)3][(H2L3)(H2O)]

The ion-selective properties of 1,8-bis[2-(dihydroxyphosphinyl)phenoxy]-3,6-dioxaoctane (H₄L³) have been studied and its potentiometric selectivity coefficients have been determined. New complexes [Cu(H₄L³)(H₂O)₃][(H₂L³)(H₂O)] (I) and Zn(H₄L³)(H₂L³) · 3H₂O, and Cu(H₂L³) · 2(H₂O) have been synthesized and characterized. The crystal and molecular structure of I has been determined by X-ray crystallography and vibrational spectroscopy. The crystals are monoclinic, a = 10.279(5) Å, b = 26.532(13) Å, c = 8.399(4) Å, β = 99.270(8)°, V = 2260.8(7) ų, Z = 2, space group Cm, R = 0.0347 for 4325 reflections with I > 2σ(I). Ionic compound I is composed of the [Cu(H₄L³)(H₂O)₃]²⁺ complex cations and [(H₂L³)(H₂O)]^2? anions. In the cation, the Cu²⁺ cation located in the m plane is bound to a tetragonal pyramidal (TP) array. The equatorial plane of the TP is formed by two phosphoryl oxygen atoms of the podand (Cu(1)-O, 1.921(2) Å) and two O atoms of two water molecules (av. Cu(1)-O, 1.981(3) Å). The third water molecule is at the axial vertex of the TP at a considerably larger distance (Cu(1)-O, 2.139(3) Å). The anion is of the host-guest type. The host is the deprotonated podand (H₂L³)^2?, and the guest is the water molecule. The latter is bound to the terminal hydroxyl groups of two phosphoryl groups of the podand by two acceptor hydrogen bonds and to two central ether oxygen atoms of the (H₂L³)^2? anion by one donor bifurcated hydrogen bond. The cations and anions in the structure are linked by hydrogen bonds to form chains parallel to the c axis.     

SYNTHESIS AND CHARACTERIZATION OF DIAQUA(3-pTOLYLIMINO-2-BUTANONE OXIMATO)(3-p-TOLYLIMINO-2-BUTANONE OXIME)NICKEL(II) PERCHLORATE

Abstract

[Ni(L^?1)(HL)(H₂O)₂].ClO₄ with a Schiff base ligand L (HL = 3-p-tolylimino-2-butanone oxime) was prepared and structurally characterized by IR, cyclic voltammetry and X-ray diffraction methods. The nickel atom has distorted octahedral coordination consisting of four nitrogen atoms and two oxygen atoms. The equatorial plane is formed by two oxime nitrogen atoms and two imine nitrogen atoms of two Schiff base ligand (L^?1 and HL) with Ni‐ N bond distances between 2.01(1) and 2.11(1)Å. Water oxygen atoms occupy axial positions with Ni‐ O bond distances of 2.06(1) and 2.15(1) Å. The oxime groups in the Schiff base ligands are coordinated to Ni atom through their nitrogen atoms. One asymmetric intramolecular hydrogen bridge between the two oxime groups is found in the title complex.     

Crystal structure and thermal properties of novel Co(II) complexes with 2,6-pyridine-dicarboxylate containing infinite one-dimensional chain: [CoL1(H2O)4][Co(pydc)2]·2H2O and [Co(H2O)6]×[Co(pydc)2]L2·H2O (L1 = 1,3-bis(4-pyridyl)propane, L2 = 3-amino-1H-1,2,4-triazole, pydc = 2,6-pyridine-dicarboxylic acid)

The two title compounds were prepared from the ligand pydc with cobalt(II) acetate in the presence of L¹ and L² (L¹ = 1,3-bis(4-pyridyl)propane, L² = 3-amino-1H-1,2,4-triazole, pydc = 2,6-pyridinedicarboxylic acid). The complexes were characterized by elemental analysis, IR spectrum and single crystal X-ray diffraction. Single crystal analysis shows that in two complexes coordination number around Co atom is six with distorted octahedral geometry, and both two complexes consist of ion pairs containing cationic [Co(H₂O) _n ]²⁺ and anionic [Co(pydc)₂]^2- units.     

Synthesis and Crystal Structures of S 2 O 2 Macrocycle L, and its Silver(I) and Platinum(II) Complexes (Where L = 5,8-dioxa-2,11-dithia-[12]-o-cyclophane)

The S₂O₂-donor macrocycle, L(5,8-dioxa-2,11-dithia-[12]-o-cyclophane or 3,4-benzo-1,6-dithia-9,12-dioxocyclo-tetradecane-3-ene) was synthesized by ring closure reaction of 2,2'-(ethylenedioxy)diethanethiol with ,'-dibromo-o-xyleneunder high dilution and crystallized from methanol. The X-ray structure of L has a C₂ axis and is shown to have two S atoms oriented exodentate and two O atoms positionedendodentate to the ring cavity. Reaction of AgNO₃ with L affords monomeric [Ag(L)(NO₃)], (1)in which the Ag atom is in a distorted trigonal plane coordinated by two S atoms in a ring and to one O atom from the NO₃ ^- ion. The behavior of complex 1 in solution was also characterized by NMR titration. Reaction between K₂PtCl₄ and L affords [Pt(L)Cl₂], (2) in which the Pt atom has a distorted square-planar environment, coordinated to two S atoms of Land to two Cl^- ions in a cis arrangement.     

Synthesis, vibrational spectra, and crystal and molecular structure of copper 1,5-bis[2-(dihydroxyphosphinyl)phenoxy]-3-oxapentane dihydrate [Cu(H2L2)(H2O)2]

A new complex Cu(H₂L²)(H₂O)₂] (I), where H₄L² is 1,5-bis[2-(dihydroxyphosphinyl)phenoxy]-3-oxapentane, has been synthesized and characterized. Its molecular and crystal structure has been determined by X-ray crystallography and vibrational spectroscopy. In mononuclear complex I, the copper(II) cation is in a distorted square-planar environment of two water oxygen atoms and two oxygen atoms of the chelating dianion (H₂L²)^2?. The crystals are orthorhombic, space group Cmc2₁, a = 25.909(5) ?, b = 9.1500(18) ?, c = 8.5600(17) ?, V = 2029.3(7) ?³, Z = 4, ??_calc = 1.688 g cm^?3, ?? = 1.292 cm^?1; 3107 measured reflections, 1174 reflections with I > 2.0??(I), R _int = 0.0600, GOOF = 1.413, R ₁ (I > 2??(I)) = 0.0812, wR ₂ (I > 2??(I)) = 0.2145.     

Intramolekulare Redoxreaktionen bei der thermischen Zersetzung von Additionskomplexen des Typs Mo(NO)2Cl2L2 und Mo(NO)Cl3L2

The intermediates formed from Mo(NO)₂Cl₂ L ₂ and Mo(NO)Cl₃ L ₂ by splitting-off of weakly-coordinated ligandsL (alcohols, glycols, nitriles) decompose in exothermic reactions: the decomposition products are N₂, MoOCl₄ and MoO₃. If the ligandL is strongly coordinated and is reducing (DMFA, DMSO, Pph₃, Asph₃), the NO groups oxidize the ligandL by formation of N₂ in an exothermic intramolecular redox process under 300?. The central atom is oxidized by NO, and N₂O is formed above 300? in the case of non-reducing ligandsL (OPph₃, OAsph₃). An endothermic redox reaction with chlorine formation is observed during decomposition of the trichloro complex. The solid residue is metallic molybdenum.     

Silver(I) and mercury(II) complexes with N,N′-bis(acetylacetone)-1R,2R-diaminocyclohexane ligands exhibiting three different coordination modes

Treatment of AgNO₃ with one equiv. of N,N′-bis(acetylacetone)-1R,2R-diaminocyclohexane (L) afforded a mononuclear complex [Ag(η²-L)NO₃] (1) in which the central silver(I) atom adopts a distorted trigonal planar geometry by coordinating two carbon atoms of the methane moieties of the ligand and one oxygen atom of the NO₃^? group. Interaction of CF₃COOAg with one equiv. of L produced a one-dimensional coordination polymer [Ag₂(μ-L)(CF₃CO₂)₂]_n (2). Each silver(I) in 2 exhibits highly distorted square planar coordination geometry that connects one oxygen atom of L and one neighboring Ag atom with the Ag?Ag interactions. Reaction of HgCl₂ with one equiv. of L resulted in the formation of one-dimensional [{Hg(μ-Cl)Cl}₂(μ-η¹-L)]_n (3) with a C-coordinated dinuclear mercury(II) chloride moiety being linked by L.     

Spectral characteristics and structures of metal complexes with 3-Hydroxy-4,6-dinitro-2-ethoxypyridine: Crystal and molecular structures of di(3-hydroxy-4,6-dinitro-2-ethoxypyridinato)diaquacopper(II)

Seven complexes of manganese(II), copper(II), cadmium, silver(I), samarium(III), and praseodymium( III) with 3-hydroxy-4,6-dinitro-2-ethoxypyridine (HL) were isolated in the crystalline state and studied by IR and UV spectroscopy. The molecular and crystal structures of di(3-hydroxy-4,6-dinitro-2-ethoxypyridinato) diaquacopper(II) [CuL₂(H₂O)₂] were determined. The coordination mode of the organic ligand L^? is bidentate chelating through the O(2) oxygen atoms of the hydroxy group and the O(1) atom of the ethoxy group. The coordination polyhedron of the copper atom is a prolate tetragonal bipyramid (4 + 2) with two O(1) atoms in the axial positions (Cu-O(1) 2.413 Å) and two O(2) atoms of the two L^?ligands and the O(7) atoms of the water molecules in the equatorial plane (Cu-O(2), 1.912 Å; Cu-O(7), 1.972 Å).     

Crystal and molecular structures of heteroligand bis(hexafluoroacetylacetonato)copper(II) complexes with 3-imidazoline nitroxyl radicals,Cu(C5HF6O2)2:L=1:1 (L1=C13H18N3O,L2=C8H15N2O)

Crystal structures were determined for two new derivatives of heteroligand complexes of Cu(C₅HF₆O₂)₂ with nitroxyl radicals derived from 3-imidazoline: Cu(C₅HF₆O₂)₂(C₁₃H₁₈N₃O) (I) and Cu(C₅HF₆O₂)₂(C₈H₁₅N₂O) (II). The unit cell parameters for I are as follows: a=10.555(3), b=15.505(5), c=18.509(6) Å, V = 3029(1) ų, Z=4, d_calc=1.57 g/cm³, space group P2₁2₁2₁. The unit cell parameters for II are as follows: a=16.018(3), b=15.886(3), c=19.665(4) Å, V = 5004(1)ų, Z=8, d_calc=1.68 g/cm³, d_exp=1.68 g/cm³, space group P2₁2₁2₁. The structure of I is molecular. The coordination of the copper ion is a trigonal bipyramid formed by two oxygen atoms of the (hfac) ions and the nitrogen atom of the imidazoline heterocycle in the equatorial plane [Cu–O, 1.91(7), 2.242(7) Å, Cu–N, 2.010(7) Å] and the other oxygen atoms of the (hfac) anion in the axial positions [Cu–O, 1.940(6), 1.963(6) Å]. Complex II is polymeric. The two crystallographically independent Cu(hfac)₂ fragments are linked in a chain by means of two L² ligands. The coordination of the copper ions is a square bipyramid, whose equatorial plane is formed by the oxygen atoms of the (hfac) anion [Cu–O, 1.89(1)–2.03(1) Å]. The axial positions are occupied by nitrogen atoms [Cu–N, 2.52(1), 2.40(1) Å] and an oxygen atom of the NO fragment [Cu–O, 2.96(1), 2.67(1) Å] of different L² ligands. The ...Cu(hfac)₂–L²–Cu(hfac)₂–L₂... chains in the unit cell are located at two levels (x1/4 and 3/4).Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 126–133, March–April, 1993.     

Catalytic efficacy of Schiff-base copper(II) complexes: Synthesis,X-ray structure and olefin oxidation

Three copper(II) Schiff-base complexes, [Cu(L¹)(H₂O)](ClO₄) (1), [Cu(L²)] (2) and [Cu(L³)] (3) have been synthesized and characterized [where HL¹ = 1-(N-ortho-hydroxy-acetophenimine)-2-methyl-pyridine], H₂L² = N,N′-(2-hydroxy-propane-1,3-diyl)-bis-salicylideneimine and H₂L³ = N,N′-(2,2-dimethyl-propane-1,3-diyl)-bis-salicylideneimine]. The structure of complex 1 has been determined by single crystal X-ray diffraction analysis. In complex 1, the copper(II) ion is coordinated to one oxygen atom and two nitrogen atoms of the tridentate Schiff-base ligand, HL¹. The fourth coordination site of the central metal ion is occupied by the oxygen atom from a water molecule. All the complexes exhibit high catalytic activity in the oxidation reactions of a variety of olefins with tert-butyl-hydroperoxide in acetonitrile. The catalytic efficacy of the copper(II) complexes towards olefin oxidation reactions has been studied in different solvent media.     

Syntheses of Monomeric,Dimeric, and Trimeric Complexes of Tungsten(VI), (V), (IV), and (III) with the 1,4,7-Triazacyclononane (L) Ligand. Crystal Structures of Dimeric [W2L2(μ2?OH)2Br2]Br2 · 2H2O and of Trimeric [W3L3(μ3?0)(μ2-0)3][ZnBr4]2

Reactions of WL(CO)₃ (L = 1, 4, 7-triazacyclononane; C₆H₁₅N₃) with bromine under different conditions afford the monomeric W^VI compound, WO₂LBr₂, or the monomeric W^V complex, WOLBr₃. The former dimerizes in aqueous solution, yielding the [W₂O₅L₂]²⁺ cation. Two diamagnetic isomers of the W^V -dimer, [W₂O₄L₂]²⁺, have been prepared : a yellow form with terminal oxo groups in cis-positions with respect to each other and a red species containing two terminal oxo-groups in trans-positions. The cationic W^IV -trinuclear cluster, [W₃O₄L₃]⁴⁺, has been isolated as the tetrabromozincate(2-) salt and its structure has been determined by single crystal X-ray diffraction. [W₃O₄L₃][ZnBr₄]₂ crystallizes in the monoclinic space group P2₁/c with a = 12.698(2) Å, b = 21.267(6) Å, c = 15.687(7) Å, β = 92.94(3)⁰, and V = 4222 ų, d_ealed. = 2.79 g cm^?3 for Z = 4, and mol wt 1773.2. The structure was solved by direct methods using 7399 unique reflections with I≥ 2.5 σ (I). Final residuals were R₁ = 0.089 and R₂ = 0.096. The structure consists of [W₃L₃O₄]⁴⁺ cations of the M₃X₁₃ cluster type and isolated ZnBr₄^2? anions. Three tungsten atoms occupy the corners of an equilateral triangle bridged by three μ₂-oxo- and one μ₃-oxo-ligands; each tungsten atom has a distorted octahedral environment of three oxygen and three nitrogen atoms. The short W - W distances of 2,52 Å and the diamagnetism indicate metal-metal bonding. The green, diamagnetic binuclear W_III complex, [W₂L₂(μ? OH)₂Br₂]Br₂ · 2 H₂O, has been prepared by reduction of monomeric WLOBr₃ in strongly acidic solution with zinc powder. The complex has been characterized by a single-crystal X-ray diffraction study; it crystallized in the orthorhombic space group Pnnm with a = 13.837(5) Å, b = 11.657(6) Å, c = 7.832 Å, and V = 1263 ų, d_calcd. = 2.67 g cm^?3 for Z = 2, and mol wt 1015.8. The structure was solved by direct methods using 783 unique reflections with I ? 2.5 σ(1). Final residuals were R₁ = 0.062 and R₂ = 0.084. The structure consists of dimeric cations [W₂L₂(μ? OH)₂Br₂]²⁺, bromide anions and molecules of water of crystallization. The tungsten centers are in a distorted octahedral environment of the tridentate N-donor igand, one coordinated bromide and two μ₂-hydroxo bridges (edge sharing), respectively. The bromide ligands are in trans-positions with respect to each other. The four-membered W₂(μ? OH)₂ ring is planar. The W? W distance of 2.477(3) Å together with its diamagnetism imply the presence of a strong metal-metal bond between the tungsten(II1) centers (σ²π²δ²).     

Crystal structure and triboluminescence of the [Tb(BTFA)2(NO3)(TPPO)2] complex

The crystal structure of the [Tb(BTFA)₂(NO₃)(TPPO)₂] complex (TPPO is triphenylphosphine oxide, BTFA is benzoyltrifluoracetone), which exhibits strong triboluminescence, has been established by X-ray crystallography. The crystals are triclinic: a = 11.668(3) Å, b = 11.700(3) Å, c = 12.512(3) Å, α = 65.161(4°), β = 79.120(4)°, γ = 61.860(4)°, space group P1, Z = 1. The central terbium(III) atom coordinates two oxygen atoms from two triphenylphosphine oxide molecules (Tb-O, 2.264(3) and 2.273(3) Å), two oxygen atoms from the nitrate group (Tb-O, 2.460(3) and 2.476(3) Å), and four oxygen atoms from two benzoyltrifluoroacetonate groups (Tb-O, 2.329(3), 2.399(3), 2.351(3), and 2.367(3) Å). The coordination polyhedron of the Tb(III) atom is a distorted dodecahedron. The photoluminescence and triboluminescence spectra of the [Tb(BTFA)₂(NO₃)(TPPO)₂] complex are identical and caused by the f-f luminescence of Tb³⁺.     

Kinetics of the Base-Catalysed Isomerization of trans-meso-CH3Co(H2O)L2+ (L = 5,7,7,12,14,14-Hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene)

The isomerization of the complex trans-meso-CH₃Co(H₂O)L²⁺ (L = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) to trans-primary, rac-CH₃Co(H₂O)L²⁺ has been investigated from pH range 7.11 to 8.09 in aqueous solution. The reaction rate law has been determined as: -d[meso-CH₃Co(H₂O)L²⁺]/dt = k_OH [OH^?][meso-CH₃Co(H₂O)L²⁺], where k_OH = 600 ± 10 M^?1s^?1 at 25 °C and μ = 0.5 M. The activation parameters of the reaction were also studied with ΔH^± = 19.1 ± 0.9 Kcal mol^?1 and ΔS^± = 18.0 ± 0.8 cal K^?1mol^?1. A mechanism that involves a secondary NH inversion is proposed.     

Hydrothermal synthesis,characterization and properties of a d10 metal coordination polymer with a layered structure based on carboxyphosphinate ligand, 4,4′-bipyridine and four-coordinated zinc ion

Abstract

Hydrothermal reaction of Zn(NO₃)₂ · 6?H₂O with 2-carboxyethyl(phenyl)phosphinate (H₂L) and 4,4'-bipyridine (4,4′-bipy) led to a novel zinc(II) carboxyphosphinate [ZnL(4,4′-bipy)_0.5]_n (1). The zinc ion is tetrahedrally coordinated by two phosphinate oxygen atoms, one carboxylate oxygen atom, and one nitrogen atom of 4,4′-bipy ligand. The L^2- ligand and zinc ion can be seen as three- and four-connected nodes, respectively. Compound 1 shows a layered network with (3,4)-connected topology. It exhibits a broad blue fluorescent emission band at 459?nm, which can be attributed to 4,4′-bipy intraligand emission as well as to H₂L emission. It is a diamagnetic system between 300?K and 11?K.     

Crystal structure of NaBa2[Co(Edta)]2(ClO4)3 · 9H2O

Crystals of Ba Na ethylenediaminetetraacetatocobaltate(III) perchlorate, NaBa₂[Co(Edta)]₂(ClO₄)₃ · 9H₂O, contain two crystallographically nonequivalent Ba²⁺ cations and two complex cations [Co(Edta)]^? (Edta^4? is ethylenediaminetetraacetic acid anion), the latter anions showing opposite chirality. The nearest surrounding of the Ba²⁺ ions involves three water molecules (including two bridging water molecules), six O atoms of four complexes [Co(Edta)]^? and the perchlorate O atom. Tetrameric fragments Ba₂(H₂O)₄[Co(Edta)]₂(ClO₄)₂ are united through the Ba-O bonds into layers with the Ba atoms in the middle of the layers and the perchlorate ions and complex anions at the periphery; in the latter anions, noncoordinated O atom of one of the R-metallocycles is directed outside. The Na atom of the Na(H₂O)(ClO₄) group located between the layers is bonded to these O atoms of the neighboring layers.     

Cu(II) and Pd(II) complexes of N-(2-hydroxybenzyl)aminopyridines

N-(2-Hydroxybenzyl)aminopyridines (Lⁱ) react with Cu(II) and Pd(II) ions to form complexes in the compositions Cu(Lⁱ)₂(CH₃COO)₂ · nH₂O (n = 0, 2, 4), Pd(Lⁱ)₂Cl₂ · nC₂H₅OH (n = 0, 2) and Pd(L²)₂Cl₂ · 2H₂O. In the complexes, the ligands are neutral and monodentate which coordinate through pyridinic nitrogen. Crystal data of the complexes obtained from 2-amino pyridine derivative have pointed such a coordinating route and comparison of the spectral data suggests the validity of similar complexation modes of other analog ligands. Cu(II) complex of N-(2-hydroxybenzyl)-2-aminopyridine (L¹), [Cu(L¹)₂(CH₃COO)₂] has slightly distorted square planar cis-mononuclear structure which is built by two oxygen atoms of two monodentate carboxylic groups disposed in cis-position and two nitrogen atoms of two pyridine rings. The remaining two oxygen atoms of two carboxylic groups form two Cu and H bridges containing cycles which joint at same four coordinated copper(II) ion. IR and electronic spectral data and the magnetic moments as well as the thermogravimetric analyses also specify on mononuclear octahedric structure of complexes [Cu(L²)₂(CH₃COO)₂ · 2H₂O] and [Cu(L³)₂(CH₃COO)₂ · 4H₂O] where L² and L³ are N-(2-hydroxybenzyl)-2- or 3-aminopyridines, respectively.     

A linear Cu-Gd-Cu-Gd complex derived from the assembly reaction of [NaCuH3L] and [Gd(thd)3(H2O)2] (H3L = meso-1,2-diphenyl-1-(2-oxybenzamido)-2-(2-oxy-3-ethoxybenzylideneamino)ethane and Hthd = 2,2,6,6-tetra-methyl-3,5-heptanedione)

A linear tetranuclear Cu^II-Gd^III-Cu^II-Gd^III complex [Cu^IIL^dpen(meso)Gd^III(thd)₂(H₂O)]₂ was synthesized from the reaction of [NaCu^IIL^dpen(meso)(DMF)] with [Gd^III(thd)₃(H₂O)₂], and the structures and magnetic properties were investigated, where H₃L^dpen(meso) = meso-1,2-diphenyl-1-(2-hydroxybenzamido)-2-(2-hydroxy-3-ethoxybenzylideneamino)ethane and Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione. The Cu^II complex component [NaCu^IIL^dpen(meso)(DMF)] has a one-dimensional (1D) chain structure, in which the Na⁺ ion is coordinated by two phenoxo and an ethoxy oxygen atoms of a Cu^II complex and an amido oxygen atom of the adjacent Cu^II unit to produce the 1D structure, in which the diphenylethylenediamine moieties have the array of {(1R,2S)-Na-(1S,2R)}_1∞. The assembly reaction of the Cu^II and Gd^III components gave a linear complex with the array of Cu(1)-Gd(1)-Cu(2)-Gd(2), in which two diphenylethylenediamine moieties have the same chirality of (1R,2S)-(1R,2S) or (1S,2R)-(1S,2R). Two linear Cu(1)-Gd(1)-Cu(2)-Gd(2) units are linked by hydrogen bonds through two water molecules to give a cyclic structure with a center of symmetry. The temperature dependence of the magnetic susceptibilities and field-dependent magnetization revealed the ferromagnetic interaction between the Cu^II and Gd^III ions within the linear chain.     

Trichloro- and methyldichlorogermyl monochelates and dibromo- and dichlorogermyl bischelates derived from N,N-disubstituted amides of 2-hydroxycarboxylic acids

The reactions of GeCl₄, GeBr₄, and MeGeCl₃ with O-trimethylsilyl derivatives of N,N-disubstituted amides of 2-hydroxycarboxylic acids afforded pentacoordinate and hexacoordinate neutral (O,O)-mono- and (O,O)-bischelates. The reactions of glycolic acid derivatives with GeX₄ produced bischelates X₂Ge[OCH₂C(O)NR²R³]₂ 7a,c,d (X = Cl, R² = R³ = Me (a), (CH₂)₅ (c), (CH₂CH₂)₂O (d)) and 8a (X = Br). By contrast, the reactions of lactic and mandelic acid derivatives with GeCl₄ and MeGeCl₃ gave monochelates Cl₃Ge[OCH(R¹)C(O)NR²R³] (S)-9a–c (R¹ = Me) and Cl₂MeGe[OCH(R¹)C(O)NR²R³] 10a (R¹ = H), (S)-11a,b (R¹ = Me), and (S)-12a (R¹ = Ph) (R²R³ = (CH₂)₄ (b)), respectively. According to the X-ray diffraction data, the Ge atom in bischelates 7c,d and 8a has a coordination number 6, and its coordination polyhedron can be described as a slightly distorted octahedron. In monochelates (S)-9a-c, 10a, (S)-11a,b, and (S)-12a, the Ge atom has a coordination number 5, and its coordination polyhedron can be described as a trigonal bipyramid with two halogen atoms or one halogen atom and one ethereal oxygen atom in equatorial positions and the halogen atom and the amide oxygen atom in the axial positions. The bonds in the axial positions are somewhat longer than the corresponding bonds in tetracoordinate Ge compounds.     

Preparation, spectroscopic properties of 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) lanthanide complexes and the supramolecular structure of [Nd2L2(NO3)6(H2O)2]·H2O

The reaction of lanthanide nitrate with 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) yields six novel Ln(III) complexes ([Ln₂L₂(NO₃)₆(H₂O)₂]·H₂O) which are characterized by elemental analysis, thermogravimetric analysis (TGA), conductivity measurements, IR, electronic and ¹H NMR spectroscopies. A new quinoxalinedione-based ligand is used as antenna ligand to sensitize the emission of lanthanide cations. The lowest triplet state energy level of the ligand in the nitrate complex matches better to the resonance level of Eu(III) and Sm(III) than Tb(III) and Dy(III) ion. The f-f fluorescence is induced in the Eu³⁺ and Sm³⁺ complexes by exciting into the π-π* absorptions of the ligand in the UV. Furthermore, the crystal structures of a novel binuclear complex [Nd₂L₂(NO₃)₆(H₂O)₂]·H₂O has been determined by single-crystal X-ray diffraction. The binuclear [Nd₂L₂(NO₃)₆(H₂O)₂]·H₂O complex units are linked by the intermolecular hydrogen bonds and π-π interactions to form a two-dimensional (2-D) layer supramolecule.     

Synthesis and spectroscopic properties of [N-(4-carboxyphenyl) salicylideneiminato] di- and tri-organotin (IV) complexes and crystal structures of {[Bu2Sn(2-OHC6H4CHNC6H4COO)]2O}2 and Ph3Sn(2-OHC6H4CHNC6H4COO)

Reactions of R₂SnO (R: ⁿBu, Cy, Ph, PhCH₂) and R₃SnCl (R: Ph, Cy, PhCH₂, 2-Cl-PhCH₂, 4-F-PhCH₂, 4-Cl-PhCH₂) with N-(4-carboxyphenyl)-salicylideneimine (LH₂) in 1:1 stoichiometry afford complexes {[R₂Sn(LH)]₂O}₂ and R₃Sn(LH). These complexes have been characterized by elemental analyses, IR, ¹H and ¹¹⁹Sn NMR spectroscopy. The crystal structures of {[ⁿBu₂Sn(LH)]₂O}₂, 1 and Ph₃Sn(L), 5 are determined by single crystal X-ray diffraction. Results showed that in the solid state the complex 1 is a tetranuclear centrosymmetric dimer with six-coordination being assigned to both the endo-cyclic and exo-cyclic tin atoms after consideration of close intermolecular tin oxygen contacts, and study show that the imino nitrogen atom do not participate in coordination to the tin atom. The complex 5 is a monomer, and in the molecule the tin atoms are five-coordinated in trigonal bipyramidal geometries with the two oxygen atom of the carboxylate both coordinating to the tin atoms.