Palladium(II) complexes of 1,10-phenanthroline: Synthesis and X-ray crystal structure determination

Two palladium(II) complexes, [Pd(phen)(NCCH₃)₂][O₃SCF₃]₂ (1) and [Pd(phen)(μ-OH)]₂[O₃SCF₃]₂ · 2H₂O (2) (where phen = 1,10-phenanthroline), have been crystallized following the reaction of Pd(phen)Cl₂ with silver triflate, Ag(O₃SCF₃), in acetonitrile and water, respectively. The structures of both complexes are based on a Pd(phen)²⁺ metal core, with two acetonitrile molecules binding in a monodentate fashion in complex 1 and two hydroxo bridges holding together two cores to form a dimer in complex 2. Additionally, both complexes present a hydrogen bonded 3-D network involving the triflate anions in 1, and water and triflate anions in 2. Both complexes have been characterized by infrared and ¹H NMR spectroscopy and their crystal structures determined by X-ray crystallography.     

Sulfhydryl-selective, covalent labeling of biomolecules with transition metallocarbonyl complexes. Synthesis of (eta5-C5H5)M(CO)3(eta1-N-maleimidato) (M = Mo, W), X-ray structure, and reactivity studies

The photochemical reaction of (eta5-C5H5)Mo(CO)3I with maleimide in the presence of diisopropylamine yielded complex (eta5-C5H5)Mo(CO)3(eta1-N-maleimidato) 4 in 52% yield. The single-crystal X-ray structure of this complex was determined and shows unusual interactions between oxygen atoms of the maleimidato ligand and carbon atoms of the cis-CO ligands. The tungsten analogue of 4, (eta5-C5H5)W(CO)3(eta1-N-maleimidato) 5, was synthesized in 37% yield by the reaction of (eta5-C5H5)W(CO)3I with the thallium(I) salt of maleimide. Complexes 4 and 5 reacted with cysteine ethyl ester and glutathione to afford products of the addition of the sulfhydryl group to the ethylenic bond of the maleimidato ligand. The reaction of 4 and 5 with glutathione proceeded faster than the reaction of the analogous complex (eta5-C5H5)Fe(CO)2(eta1-N-maleimidato) (3). However, all these complexes react with glutathione more slowly than N-ethylmaleimide. Complexes 4 and 5 were used for labeling of bovine serum albumin (BSA), enriched in thiol groups by reaction with Traut's reagent. Reaction of thiolated BSA containing 7.4 SH groups with 4 and 5 gave bioconjugates bearing 6.9 and 6.4 metallocarbonyl moieties, respectively. Under the same conditions, reaction with 3 afforded a BSA conjugate containing 7.6 metallocarbonyl moieties. Labeling was presumed to be site-specific, as the number of metallocarbonyl entities matched very well with the initial number of SH groups measured for the thiolated BSA sample. IR spectra of BSA labeled with 4 and 5 show intense nu(C[triple bond]O)) bands (2042 and 1948 cm(-1) in the latter case), enabling sensitive detection of the bioconjugates in biological samples. Complexes 4 and 5 (especially the latter) should be of interest as heavy atom phasing reagents for protein X-ray crystallography.     

Linkage isomerism in the metal complex hexa(thiocyanato)rhenate(IV): Synthesis and crystal structure of (NBu4)2[Re(NCS)6] and [Zn(NO3)(Me2phen)2]2[Re(NCS)5(SCN)]

The linkage isomers [Re(NCS)₆]^2? and [Re(NCS)₅(SCN)]^2? are obtained by the reaction of [ReBr₆]^2? with NCS^? in dimethylformamide. Some differences in the chemical behavior allowed their separation and structural characterization in the form of (NBu₄)₂[Re(NCS)₆] (1) and [Zn(NO₃)(Me₂phen)₂]₂[Re(NCS)₅(SCN)] (2), respectively (Bu = n-C₄H₉ and Me₂phen = 2,9-dimethyl-1,10-phenanthroline).     

Synthesis,characterisation and reactivity of oxodiperoxo-[2-(1-pyrazolyl)-6-menthylpyridine]molybdenum(VI): The first chiral 2-(1-pyrazole)pyridineoxodiperoxomolybdenum(VI) complex

We have obtained a novel chiral enantiomerically pure molybdenum complex of the type MoO(O₂)₂LL′ which has been fully characterised, including structural determination by X-ray crystallography and screened in a series of epoxidation reactions with simple olefins giving satisfactory conversions, but low enantioselectivities. It’s mode of epoxidation has been investigated.     

Amine free crystal structure: the crystal structure of d(CGCGCG)2 and methylamine complex crystal

We succeeded in the crystallization of d(CGCGCG)2 and methylamine Complex. The crystal was clear and of sufficient size to collect the X-ray crystallographic data up to 1.0 A resolution using synchrotron radiation. As a result of X-ray crystallographic analysis of 2Fo-Fc map was much clear and easily traced. It is the first time monoamine co-crystallizes with d(CGCGCG)2. However, methylamine was not found from the complex crystal of d(CGCGCG)2 and methylamine. Five Mg ions were found around d(CGCGCG)2 molecules. These Mg ions neutralized the anion of 10 values of the phosphate group of DNA with five Mg2+. DNA stabilized only by a metallic ion and there is no example of analyzing the X-ray crystal structure like this. Mg ion stabilizes the conformation of Z-DNA. To use monoamine for crystallization of DNA, we found that we can get only d(CGCGCG)2 and Mg cation crystal. Only Mg cation can stabilize the conformation of Z-DNA. The method of using the monoamine for the crystallization of DNA can be applied to the crystallization of DNA of long chain of length in the future like this.     

Synthesis of metal paddlanes: X-ray structure determination of bis-(methyl nicotinate)copper(II) acetate dimer

The synthesis of nicotinic acid based N,N′-bidentate ligands capable of spanning the axial sites of copper(II) acetate dimer are reported. Reaction of these ligands with [Cu(C₂H₃0₂)₂]₂·2H₂0 gave the 1:1 adduct: a metal paddlane, which on recrystallization from MeOH/CHCl₃ yielded the trans-esterified complex [Cu(C₂H₃O₂)₂]₂·2C₇H₇N0₂, 3. A single crystal X-ray structure determination of 3 is presented.     

Synthesis, X-ray crystal structure and magnetic study of a dicyanamido bridged 1D chain nickel(II) complex

Reaction of Ni(NO₃)₂ · 6H₂O and sodium dicyanamide (Nadca) yields a 1D infinite chain complex {[Ni(dien)(μ_1,5-dca)(H₂O)](NO₃)}_n (1) (where dien = diethylenetriamine). The coordination environment in complex 1 around the nickel(II) ions is distorted octahedron. Three nitrogen atoms of the ligand diethylenetriamine and an oxygen atom of H₂O molecule constitute the four coordination sites of the basal plane of the octahedron. Of two axial positions of the octahedron, one position is occupied by the nitrogen atom of a μ_1,5-dca anion the remaining coordination site is occupied by a nitrogen atom of another end-to-end bridging dca from an adjacent [Ni(dien)(μ_1,5-dca)(H₂O)] moiety, yielding 1D infinite chains which propagate parallel to crystallographic a-axis. No measurable magnetic interaction was evidenced through variable temperature magnetic susceptibility measurements (4-300 K). However, the magnetic susceptibility of the compound can be explained in terms of single-ion anisotropic model with zero-field splitting for nickel(II) ions.     

Synthesis, crystal structure and EPR of a hydrogen bonded two-dimensional network of Cu(II) complex with N-(2-hydroxybenzyl)-2-amino-1-ethanol

Hsalea (N-(2-hydroxybenzyl)-2-amino-1-ethanol) and its Cu(II) complexes, Cu(salea)₂ (1) and CuH₋₁(salea)·1.5H₂O (2), were prepared and characterized. X-ray structural analyses of 1 show that two amino N and two deprotonated phenoxy O atoms of the two ligands coordinate equatorially to Cu(II). Two alcoholic O atoms coordinate weakly at axial positions. Each molecule utilizes two alcoholic H atoms and two phenoxy O atoms to form hydrogen bonds with four surrounding molecules, leading to a two-dimensional network structure. EPR and electronic spectra of 1 are consistent with the elongated octahedral coordination polyhedron.     

Synthesis of sodium 2,6-dimesitylphenyl phosphanide and X-ray crystal structure determination of its 15-crown-5 adduct

The synthesis of the first terphenyl-based sodium phosphanide, namely DmpP(H)Na (1) (Dmp=2,6-dimesitylphenyl) as well as the X-ray crystal structure determination of a crown ether adduct of the sodium salt, namely DmpP(H)Na(15-crown-5) (2) are reported. Compound 2 crystallizes in the triclinic space group P1?. Crystal data for 2 at 198 K: a=10.5342(4) Å; b=12.0538(5) Å; c=14.4023(6) Å; α=79.9474(9)°; β=72.2234(10)°; γ=70.0716(10)°; V=1632.1(2) ų; Z=2; D_calc=1.198 g cm⁻³; R_F=7.91%. The molecular structure of 2 features a monomeric arrangement in the solid state and a bent NaPC(ipso) moiety [Na(1)P(1)C(16)=116.3(2)°].     

Synthesis,reactivity, and X-ray crystal structure of a remarkably stable bis(alkoxo)platinum complex

Platinum complexes of the ligand Ph₂PCH₂CMe₂OH are described including [Pt(PPh₂CH₂CMe₂O)₂] which contains PtO bonds of unprecedented stability that readily undergo insertion of SO₂ and CO.     

Triorganotin(IV) complexes of Schiff base derived from 6-amino-2-mercaptobenzothiazole: Synthesis, characterization and X-ray crystal structures

Nine triorganotin(IV) complexes of the type R₃SnL (L = L1 R = Me 1, Ph 2, PhCH₂3; L = L2 R = Me 4, Ph 5, PhCH₂6; L = L2 R = Me 7, Ph 8, PhCH₂9) have been obtained by reaction of new Schiff base HL1, HL2 or HL3 with triorganotin(IV) chloride in the presence of sodium ethoxide. All the complexes 1-9 were characterized by elemental, IR and NMR spectra analyses. Except for complexes 3, 4, 6, 9, the others were also characterized by X-ray crystallography diffraction analyses, which revealed that complexes 1, 2, 5, 7, 8 were four coordinated and displayed a capped tetrahedron.     

Synthesis and X-ray crystal structure of a polymeric copper(II) complex containing the novel ligand 4,4-(1,4-phenylene)bis[3-phenyl-5-(2-pyridyl)-4H-1,2,4-triazole]

The synthesis and X-ray crystal structure of the complex {[Cu^II(Ph₂PBPT)(bpy)](ClO₄)₂ · 2DMF}_∞ where Ph₂PBPT=4,4^′-(1,4-phenylene)bis[3-phenyl-5-(2-pyridyl)-4H-1,2,4-triazole], bpy=2,2^′-bipyridine and DMF=N,N-dimethylformamide are reported. In this one-dimensional coordination polymer the Cu²⁺ ions are in a distorted octahedral N₆ coordination environment made up of two Ph₂PBPT molecules, each chelating via one pyridine and one triazole nitrogen, and one bpy co-ligand. Within the zig-zag chain thus formed the shortest distance between two metal centres across the Ph₂PBPT ligand is 13.305(3) Å while it is 10.009(3) Å between two chains. This complex represents the first structurally characterised example of a coordination compound incorporating a chelating 4,4^′-bis(4H-1,2,4-triazole) as a ligand.     

Synthesis of 2-amino-2-deoxy-beta-glycosyl-(1-->5)-nucleosides and the interaction with RNA

1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranose and 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-beta-D-galactopyranose reacted with protected nucleosides in the presence of BF(3) as promoter at room temperature to give selectively 2-amino-2-deoxy-beta-glycosyl (1-->5)nucleosides in good yields. CD spectra and thermal melting studies showed that 2-amino-2-deoxy-beta-D-glucopyranosyl-(1-->5)-nucleosides could interact with RNA in solution and 2-deoxy-2-amino-beta-D-galactopyranosyl-(1-->5)-nucleosides (17-19) exhibit higher affinity to RNA than 2-deoxy-2-amino-beta-D-glucopyranosyl-(1-->5)-nucleosides (14-16). It indicated that the majority of interactions are established between the polar group of glycosylnucleosides and the sugar-phosphate backbone of RNA helices and weak stacking interaction is observed. The different configuration of hydroxyl group on the glycosyl moiety may affect the glycosyl-nucleoside binding to RNA by induced fit.     

Synthesis and structure determination of [8(-13)C]guanosine 5'-diphosphate

A combined chemical and enzymatic synthesis of [8(-13)C]guanosine 5'-diphosphate (GDP) from H13COOH is described. About 35 mg nucleotide was obtained from 500 mg H13COOH. Analysis of the [8(-13)C]GDP by negative ion fast atom bombardment mass spectrometry and by 13C NMR confirmed that one atom of 13C was incorporated at the 8-position of the guanine ring at 90 +/- 10% enrichment. The chemical shift of the C(8) was 140.2 ppm downfield from internal trimethylsilylpropionate at neutral pH and room temperature, with a spin-spin coupling 1J(13C(8)-H(8] of 217 Hz and a 3J(13C(8)-H(1'] of 3.9 Hz.     

Synthesis and metal complexes of 2,6-bis(1-triazolo)pyridine: X-ray structure of 2,6-bis(1-triazolo)pyridine dihydrochloride

2,6-Bis(1-triazolo)pyridine (1) was synthesized and characterized via IR and NMR. The regiochemistry of the compound was confirmed via single crystal X-ray analysis of the hydrochloride salt. A series of insoluble complexes of the general formulae M(1)₂(X)₂ or M(1)(X)₂ [M=Co(II), Ni(II), Cu(II); X=ClO₄, BF₄, Cl] were prepared and their structures interpreted in light of infrared spectra and composition analysis. The results suggest that first row transition metals are not chelated by 1, but rather form extended coordination polymeric networks. A second family of complexes was prepared using 2,6-bis(1-imidazolo)pyridine to support this interpretation.     

Determination of the NMR solution structure of the Hoechst 33258-d(GTGGAATTCCAC)2 complex and comparison with the X-ray crystal structure

BACKGROUND: The chromosomal stain, Hoechst 33258, binds to the minor groove of the DNA double helix and specifically recognizes a run of four A-T base pairs. Extensive biochemical and biophysical studies have been aimed at understanding the binding of the dye to DNA at the atomic level. Among these studies there have been several crystal structure determinations and some preliminary structural studies by NMR. RESULTS: On the basis of our own previously reported NMR data, we have now determined the three-dimensional solution structure of the 1:1 complex between Hoechst 33258 and the self-complementary DNA duplex d(GTGGAATTCCAC)2. Two coexisting families of con formers, which exhibit differences in their intermolecular hydrogen bonding pattern, were found and the two terminal rings of the dye displayed greater internal mobility than the rest of the molecule. CONCLUSIONS: The observed multiple ligand-binding modes in the complex between Hoechst 33258 and DNA and differential internal mobility along the bound ligand provide a novel, dynamic picture of the specific inter actions between ligands that bind in the minor groove and DNA. The dynamic state revealed by these studies may account for some of the significant differences previously observed between different crystal structures of Hoechst 33258 complexed with a different DNA duplex, d(CGCGAATTCGCG)2.     

Interactions of biotin with metal ions. X-ray crystal structure of the polymeric biotin--silver(I) nitrate complex: metal bonding to thioether and ureido carbonyl groups

X-ray structure analysis of the silver(I) complex of d-(+)-biotin, [Ag(biotin)(NO3)] X 0.5H2O, shows the complex to be polymeric with the silver ion coordinated tetrahedrally to nitrate and to three different biotin molecules. Binding to the latter involves two thioether sulfur atoms in the cis and trans direction with respect to the ureido ring, and one ureido carbonyl oxygen atom. The biotin carboxylate group is probably protonated and not coordinated with the silver ion.     

Synthesis and X-ray crystal structure determination of two pseudopolymorphic forms of μ-[1,2-bis(diphenylphosphino)ethane] bis [chlorogold(I)]: a digold(I) DNA binder

An improved synthetic route to the linearly coordinated digold(I) complex, μ-[1,2-bis(diphenylphosphino)ethane]bis[chlorogold(I)], is reported. This complex crystallizes in two pseudopolymorphic forms from a chloroform/methylene chloride solution; the crystal and molecular structures of both are discussed and compared. In both crystal forms the potentially chelating diphenylphosphinoethane (dppe) ligand instead coordinates to two separate gold atoms. The coordination environment of each gold atom is linear in both pseudopolymorphs and the structures display normal goldchloride and goldphosphorus bond distances. On the molecular level, the pseudopolymorphs differ fundamentally by a twist about one of the gold phosphorous bonds with the phosphorous atoms of the dppe ligand adopting a transoid orientation relative to one another in both polymorphs. These conformations thus place the intramolecular gold atoms 6 Å apart and preclude intramolecular AuAu bonding interactions. As has been observed for related gold(I) complexes there are short intermolecular AuAu contacts of the order of 3.2 Å present in both structures. The conformational flexibility of the gold complex relative to its observed biological activity as a DNA binder is discussed.     

Synthesis, characterization and antiproliferative behavior of tricarbonyl complexes of rhenium(I) with some 6-amino-5-nitrosouracil derivatives: crystal structure of fac-[ReCl(CO)3(DANU-N5,O4)] (DANU=6-amino-1,3-dimethyl-5-nitrosouracil)

New complexes of rhenium(I) with some 5-nitrosopyrimidines with general formula [ReCl(CO)3L] have been prepared and characterized by elemental analysis, conductivity measurements, IR and 1H, 13C and 15N NMR spectroscopic methods. The complexes appear to be monomeric and the pyrimidine ligands act in a neutral form. The structure of [ReCl(CO)3(DANU)].CH3CN has been solved by X-ray diffraction. The coordination environment around the Re(I) may be described as a distorted octahedron in which the ligand behaves in a bidentate fashion through N5 and O4 atoms, making a five-membered chelate ring. The coordination sphere is completed with three carbonyl groups in fac-arrangement and one chlorine atom. The evaluation of the antiproliferative behavior against five human tumor cell lines (human breast cancer MCF-7 and EVSA-T, human neuroblastoma NB69, human glioma H4 and human bladder carcinoma cell line ECV) suggested a modulator behavior of cell growth at low concentrations due to their estrogenic-like characteristics.