Borchelate und Bormetallchelate, 4. Mitt.

The i.r., u. v.,¹H n.m.r.,¹³C n.m.r., and¹¹B n.m.r. spectra of several substituted diphenylboron chelates derived from salicylaldehyde azomethines were compared with respect to the influence of the amine substituentR. O–B–N-6-ring constitution of the chelates29–32 [R=OH, NH₂, NHC₆H₅, N(CH₃)₂] can be deduced from the spectra.

Als 3. Mitt. gilt:F. Umland undE. Hohaus mit Beiträgen vonW. Riepe, K. Brodte, C. Schleyerbach undD. Szonn. Untersuchungen über borhaltige Ringsysteme vom Chelattyp. Forschungsbericht des Landes Nordrhein-Westfalen Nr. 2538. Opladen: Westdeutscher Verlag. 1976.     

Chelate synthesis of 8-diaminomethylene-5,6,7,8-tetrahydroquinazoline-7-one derivatives

A scheme for synthesizing 5,6,7,8-tetrahydroquinazoline systems from ketene aminal1 via its diphenylboron chelate2 has been suggested. The interaction ofp-toluamidine with the condensation product of the chelate with dimethylformamide dimethylacetal results in the formation of 8-(N-benzoyldiaminomethylene)-2-p-tolyl-5,6,7,8-tetrahydroquinazoline-7-one, which is easily debenzoylated by sodium ethoxide. 8-Diaminomethylene-5,6,7,8-tetrahydroquinazolinone derivatives can be used for the preparation of boron chelate complexes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 888–890, May, 1994.     

Theoretical,antimicrobial, antioxidant,in vitro cytotoxicity,and cyclin-dependent kinase 2 inhibitor studies of metal(II) complexes with bis(imidazol-1-yl)methane-based heteroscorpionate ligands

Abstract

A series of C-centered heteroscorpionate-based homoleptic manganese(II), nickel(II), and copper(II) complexes of type [M(L^1–3)₂] (1–9) have been synthesized by using the ligands (2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL¹), (4-diethylamino-2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL²) and (5-bromo-2-hydroxyphenyl)bis(imidazol-1-yl)methane (HL³). The geometric parameters of the complexes were determined using UV-vis and theoretical studies suggesting distorted octahedral geometry around metal(II) ion. Frontier molecular orbital analysis supports bioefficacy of the complexes. Antimicrobial activity of the metal(II) complexes were determined against two Gram(–ve) (Escherichia coli and Klebsiella pneumoniae) and two Gram(+ve) (Bacillus cereus and Staphylococcus aureus) bacteria, and three fungal (Candida albicans, Candida glabrata, and Candida krusei) strains. Antioxidant activity of nickel(II) and copper(II) complexes were evaluated against ABTS, DPPH, and H₂O₂ free radicals. In vitro cytotoxicity activity of nickel(II) and copper(II) complexes against human breast adenocarcinoma (MCF-7), cervical (HeLa), and lung (A549) cancer cell lines along with one normal human dermal fibroblasts (NHDF) cell line were carried out by MTT assay, which shows the potent activity of copper(II) complex 8 with respect to the standard drug cisplatin. Molecular docking studies evidence the interaction of complexes with cyclin-dependent kinase 2 receptor (CDK2).     

Structure and properties of an oxalato-bridged dinickel(II) complex with a tetraazamacrocycle bearing an aminomethyl pendant arm, 5-aminomethyl-5R(S),12R(S)-dimethyl-1,4,8,11-tetraazacyclotetradecane

The oxalato-bridged dinickel(II) complex with the title ligand, [Ni₂(L ^a H)₂(μ-ox)](ClO₄)₂·2H₂O (1), was prepared and its structure was determined by X-ray crystallography, as well as that of the monomeric nickel(II) complex, [Ni(L ^a H)ox]ClO₄·3H₂O (2). In Complexes 1 and 2, the ligand, L ^a , is folded along the N(4)–Ni(1)–N(11) axis. The antiferromagnetic coupling between the two nickel(II) centers in 1 was revealed and the coupling constant, J?=??17.4?cm^?1, and g?=?2.11 were estimated. It was found that the oxalato-bridged dimer 1 was readily converted to the mononuclear cis-nickel(II) complex [NiL ^a (OH₂)](ClO₄)₂ (3a), in basic aqueous solution. In [NiL ^a (CH₃CN)]I₂ (3b), which was derived from 3a, the aminomethyl pendant arm is coordinated to the Ni(II) ion and L ^a is folded along the N(1)–Ni(1)–N(8) axis.     

Condensation of bis(β-alaninato)copper(II) with formaldehyde and ammonia

Various complexes have been prepared by the template condensation of -amino acids with formaldehyde or acetaldehyde in the presence of metal ions(^1–5). In particular, glycine has received much attention(^1–4). For example, (3N, 7N-1,3,5,7-tetraazabicyclo[3.3.1]nonyl)-diacetato nickel(II) (1) has been prepared by condensing bis(glycinato)nickel(II) dihydrate with formaldehyde and ammonia at pH 8.5⁴. More recently⁵, complex (2) has been prepared by condensing bis(L-alaninato)copper(II) with formaldehyde and ammonia. These reactions are interesting for the following reasons:

Über die Reaktionen von Guanidin bzw. Harnstoff mit Aminonitrilen

The aminonitriles3a–f react with guanidine inDMF to yield the 5,5-resp. 5-subtituted imidazolidine-2,4-diimines2a–d resp.2f, whereas2e could not be isolated. 7,14-diazadispiro[5.1.5.2]-pentadecan-15-on (7)¹, 4-imino-1,3-diazaspiro[4.5]decan-2-one (8a)¹ and the 2,4-diaminotriazine (9)¹ were isolated as byproducts.1-Aminocyclohexancarbonitrile (3a) reacts with urea to the 4-imino-1,3-diazaspiro[4.5]decan-2-one (8a)¹;8a can be prepared from (1-cyancyclohexyl)urea (11a) as well. The structures of the new compounds are proved by NMR-, IR- and mass spectra and the mechanism of the reaction is discussed.

Herrn Prof. Dr.G. Zigeuner zum 60. Geburtstag gewidmet.     

Zur Anwendung der Hochdruck-Flüssigkeits-Chromatographie in der anorganischen Analytik VI. Reversed-Phase-Chromatography von PAN-Chelaten

Zusammenfassung Die Möglichkeiten und die Grenzen zur Trennung von Metall-PAN-Chelaten in Reversed-phase-Systemen durch HPLC und DC werden systematisch untersucht. Nur die Elemente Cu, Ni, Co oder Cu, Fe, Co sind trennbar. Alle anderen Metallkomplexe sind in RP-Systemen instabil. Die optimalen Trennbedingungen sind: RP-2-Phase, mobile Phase: Acetonitril/Wasser/Citratpuffer pH 5 (80:18:2), 0,01M NH₄SCN.

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Application of high-performance liquid chromatography in inorganic analysis. Reversed-phase chromatography of PAN chelates

Summary The possibilities for separation and the limits of detection of metal-PAN chelates in reversed-phase (RP) systems by HPLC and TLC are investigated systematically. Only Cu, Ni, Co or Cu, Fe, Co complexes are separable. All other metal complexes show instability in RP systems. The best conditions for separations are: RP-2 material, mobile phase: acetonitrile/water/citrate buffer pH 5, (80:18:2), 0.01M NH₄SCN.

Teil V: Chromatographia12, 289 (1979).     

Crystal structure and spectra of the Ni(II) complex of pyridine-2,6-dithio-carbomethylamide

The crystal structure of the paramagnetic bis(pyridine-2,6-dithiocarbomethylamide) nickel(II) nitrate (NiPDTA) is described: C₁₈H₂₂N₆S₄·(NO₃)₂·(H₂O)_1,5, monoclinic, C2/c,Z=4,a=14.705 (3) Å,b=23.254 (8) Å,c=8.383 (3) A, =98.18 (2)°,d _x=1.55 gcm^–3,d _m=1.53 gcm^–3. The structure was solved withPatterson and differenceFourier techniques and refined to a residual ofR=0.053. The nickel is surrounded by a square bipyramidal coordination of four thioamide sulfur atoms and two pyridine nitrogen atoms. Vibrational and electronic band positions for this compound are discussed.

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Kristallstruktur und Spektren des Pyridin-2,6-dithiocarbomethylamid Nickel(II)-Komplexes

Zusammenfassung Die Kristallstruktur des paramagnetischen bis(Pyridin-2,6-dithiocarbomethylamid) Nickel(II)-nitrats (NiPDTA) wurde bestimmt. C₁₈H₂₂N₆S₄Ni·(NO₃)₂·(H₂O)_1,5, monoklin, C2/c,Z=4,a=14,705 (3) Å,b=23,254 (8) Å,c=8,383 (3) A, =98,18 (2)°,d _x=1,55gcm^–3,d _m=1,53gcm^–3. Das Phasenproblem wurde mittelsPatterson-und Differenz-Fourier-Synthese bestimmt und die Struktur bis zu einem kristallographischenR-Faktor vonR=0.053 verfeinert. Das Nickel-Atom ist von vier Thioamid-Schwefelatomen und zwei Pyridin-Stickstoffatomen in quadratisch-bipyramidaler Anordnung umgeben. Schwingungsspektren und Anregungsspektren des Komplexes werden diskutiert.

     

Bis(oxamato)palladate(II) complexes: synthesis,crystal structure and application to catalytic Suzuki reaction

New bis(oxamato)palladate(II) complexes, [Pd(H₂O)₄][Pd(2,6-Me₂pma)₂]·2H₂O (1), (n-Bu₄N)₂[Pd(2,6-Me₂pma)₂]·2H₂O (2a), and (n-Bu₄N)₂[Pd(2,6-Me₂pma)₂]·2CHCl₃ (2b) (2,6-Me₂pma = N-2,6-dimethylphenyoxamate and n-Bu₄N⁺ = tetra-n-butylammonium), have been synthesized and the structures of 1 and 2b characterized by single-crystal X-ray diffraction. Complex 1 is a double salt constituted by tetraaquapalladium(II) cations and bis(oxamato)palladate(II) anions interlinked by hydrogen bonds. The palladium(II) ions in 1 are four-coordinate with two oxygens and two nitrogens from two fully deprotonated oxamate ligands (anion), and four water molecules (cation) building centrosymmetric square-planar surroundings. Centrosymmetric bis(oxamato)palladate(II) anions occur in 2b as in 1, the charge balance in this compound being ensured by the bulky n-Bu₄N⁺. The catalytic role of 1 and 2a for the Suzuki reaction has been investigated by using a series of aryl iodide/bromide derivatives in the conventional organic medium dimethylformamide. The tetraaquapalladium(II) unit in 1 appears to be active in the catalytic Suzuki cross-coupling reactions, but it readily decomposes to inactive palladium black.     

Preparation of samarimm(ii) sulfide by the reaction of samarium(II) bis[bis(trimethylsilyl)amide] with hydrogen sulfide

X-ray amorphous samarium(II) sulfide was prepared by the reaction of H₂S with samarium(II) bis[bis(trimethylsilyl)amide] (1) in THF at 10^–2 Torr. Compound1 was prepared by two methods: 1) the reaction of SmI₂ with lithium bis(trimethylsilyl)amide and 2) the reaction of samarium naphthalide with bis(trimethylsilyl)amine. SmS was transformed to the polycrystalline state with the lattice parametera = 5.92 Å by annealing at 400–500 °C.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 241–243, February, 1995.     

Octahedral iron(II) complexes with pyridyl triazine and bipyridine ligands – synthesis,computational studies,mechanisms and kinetics with 1,10-phenanthroline and 2,2′,6,2″-terpyridine

[Bis(3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine)(2,2′-bipyridine)iron(II)], [Fe(PDT)₂(bpy)]²⁺ (1), [bis(3-(4-phenyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine)(2,2′-bipyridine)iron(II)], [Fe(PPDT)₂(bpy)]²⁺ (2), [bis(2,2′-bipyridine)(3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine)iron(II)], [Fe(PDT)(bpy)₂]²⁺ (3), and [bis(2,2′-bipyridine)(3-(4-phenyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine)iron(II)], [Fe(PPDT)(bpy)₂]²⁺ (4) have been synthesized and characterized. Substitution of the triazine and bipyridine ligands from the complexes by nucleophiles (nu), namely 1,10-phenanthroline (phen) and 2,2′,6,2″-terpyridine (terpy) was studied in a sodium acetate-acetic acid buffer over the pH range 3–6 at 25, 35, and 45°C under pseudo-first order conditions. Reactions are first order in the concentration of complexes 1–4. The reaction rates increase with increasing [nu] and pH whereas ionic strength has no effect on the rate. Straight-line plots with positive slopes are observed when the k_obs values are plotted against [nu] or 1/[H⁺]. The substitution reactions proceed by dissociative as well as associative paths and the latter path is predominant. Observed low E_a values and negative ΔS^# values support the dominance of the associative path. Phenyl groups on the triazine ring modulate the reactivity of the complexes. The π-electron cloud on the phenyl rings stabilizes the charge on metal center by inductive donation of electrons toward the metal center, resulting in a decrease in reactivity of the complex and the order is 1 < 2 < 3 < 4. Density functional theory (DFT) calculations also support the interpretations drawn from the kinetic data.     

Trans-bis(dicyanamido)nickel(II) complexes with polyaza macrocyclic ligands

Two new trans-bis(dicyanamido)nickel(II) macrocyclic complexes, [Ni(II)(L1){N(CN)₂}₂] · H₂O (1) and [Ni(II)-(L3){N(CN)₂}₂] (2), where L1 is 3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacyclotetradecane and L3 is 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane, have been synthesized and structurally characterized by spectroscopic and X-ray crystallographic methods. In (1) and (2), each central nickel(II) ion possesses a distorted octahedral geometry with four equatorial nitrogen atoms from the macrocycle and two axial nitrogen atoms from dicyanamide anions, which are terminally bonded to the central nickel atom. The solid state electronic spectra of (1) and (2) using the diffuse reflectance method show a characteristic high-spin d⁸ nickel(II) ion in a distorted octahedral environment.     

Enhanced Anion Binding from Unusual Coordination Modes of Bis(thiourea) Ligands in Platinum Group Metal Complexes

Treatment of a range of bis(thiourea) ligands with inert organometallic transition‐metal ions gives a number of novel complexes that exhibit unusual ligand binding modes and significantly enhanced anion binding ability. The ruthenium(II) complex [Ru(η⁶‐p‐cymene)(κS,S′,N‐ L³ ?H)]⁺ ( 2 b ) possesses juxtaposed four‐ and seven‐membered chelate rings and binds anions as both 1:1 and 2:1 host guest complexes. The pyridyl bis(thiourea) complex [Ru(η⁶‐p‐cymeme)(κS,S′,N_py‐ L⁴ )]²⁺ ( 4 ) binds anions in both 1:1 and 1:2 species, whereas the free ligand is ineffective because of intramolecular NH???N hydrogen bonding. Novel palladium(II) complexes with nine‐ and ten‐membered chelate rings are also reported.     

Cyclisierungsreaktionen von Hydrazonen, 2. Mitt.: Eine neue Methode bei der Herstellung von 1-Oxo-2-aryl-1,2-dihydro-(as-triazino) [4,5-a]benzimidazol-4-carbonsäurenitrilen

Zusammenfassung Durch Kupplung von Diazoniumsalzen mit 2-Cyanmethylbenzimidazol wurden einige 2-Arylhydrazonocyanmethylbenzimidazole (1) hergestellt, durch deren Cyclisierung (Einwirkung von Chlorameisensäureäthylester in trockenem Pyridin) Nitrile der 1-Oxo-2-aryl-1,2-dihydro-(as-triazino) [4,5-a] benzimidazol-4-carbonsäuren (2) gewonnen wurden. Dieselben Verbindungen wurden auch aus 1-Carbäthoxy-2-cyanmethylbenzimidazol nach einer kürzlich¹ beschriebenen Methode gewonnen.

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Cyclization reactions of hydrazones, II: New synthesis of 1-oxo-2-aryl-1,2-dihydro (as-triazino) [4,5-a]benzimidazole-4-carbonitriles

2-Arylhydrazonocyanomethylbenzimidazoles (1), obtained from diazonium salts and 2-cyanomethylbenzimidazole, cyclize by treatment with ethyl chloroformate in dry pyridine solution to give the corresponding 1-oxo-2-aryl-1,2-dihydro-(as-triazino)-[4,5-a]benzimidazole-4-carbonitriles (2). The same compounds were prepared from 1-carbethoxy-2-cyanomethylbenzimidazole according to the method recently described¹ too.

     

Binuclear copper(II) complexes of 1-amidino-O-alkylurea (alkyl = n-propyl,n-butyl,or i-butyl) and vanadate: an EPR study

Five new complexes of bis(1-amidino-O-alkylurea)Cu(II)vanadate where alkyl?=?methyl, ethyl, n-propyl, n-butyl or i-butyl have been synthesized by reaction of ammonium metavanadate with bis(1-amidino-O-alkylurea)Cu(II)perchlorate complexes. Electron paramagnetic resonance (EPR) spectra of bis(1-amidino-O-n-propylurea)Cu(II)vanadate (1), bis(1-amidino-O-n-butylurea)Cu(II)vanadate (2) and bis(1-amidino-O-i-butylurea)Cu(II)vanadate (3) gave half-field signal (ΔM _s?=?±2) ca 1623G, in addition to fine structure due to zero field splitting (ZFS) characteristics of the S?=?1 system. From the observed ZFS the average Cu–Cu distance was estimated. The isotropic exchange constant J was evaluated by recording EPR spectra at different temperatures. The photoacoustic signal of the complexes indicated square-planar geometry around Cu²⁺. X-ray powder diffraction studies on 2 suggested orthorhombic structure with unit cell dimensions a?=?21.11?Å, b?=?24.11?Å, c?=?27.11?Å, α?=?β?=?γ?=?90°. The crystal structure of bis(1-amidino-O-n-butylurea)Cu(II)perchlorate is also reported.     

Synthese von α-Methyl-homocysteinthiolacton

Summary A facile high yield large scale methylation procedure affording2c is reported utilizing the N-[bis(methylthio)-methylen-protected derivative4a as an intermediate. The optical resolution of racemic2c is described leading to (S)-2b. In addition the thiolactone2c undergoes oxidative ring opening by bromine to the corresponding sulphonic acid5.

     

Bis‐NHC Chelate Complexes of Nickel(0) and Platinum(0)

For a long time d¹⁰‐ML₂ fragments have been known for their potential to activate unreactive bonds by oxidative addition. In the development of more active species, two approaches have proven successful: the use of strong σ‐donating ligands leading to electron‐rich metal centers and the employment of chelating ligands resulting in a bent coordination geometry. Combining these two strategies, we synthesized bis‐NHC chelate complexes of nickel(0) and platinum(0). Bis(1,5‐cyclooctadiene)nickel(0) and ‐platinum(0) react with bisimidazolium salts, deprotonated in situ at room temperature, to yield tetrahedral or trigonal‐planar bis‐NHC chelate olefin complexes. The synthesis and characterization of these complexes as well as a first example of C? C bond activation with these systems are reported. Due to the enforced cis arrangement of two NHCs, these compounds should open interesting perspectives for bond‐activation chemistry and catalysis.     

NOVEL UNSYMMETRICAL N,N-BIS(METHYLENE)BISPHOSPHONIC ACIDS OF α,ω-DIAMINES. PREPARATION AND CHARACTERIZATION OF [[(2-AMINOETHYL)IMINO]BIS(METHYLENE)]BISPHOSPHONIC ACID AND [[(6-AMINOHEXYL)IMINO]BIS(METHYLENE)]BISPHOSPHONIC ACID

Abstract

Reaction of ethylenediamine with phosphorous acid and formaldehyde in molar ratio 1:2:2 gives [[(2-aminoethyl)imino]bis(methylene)]bisphosphonic acid (2a) as the major product. Similarly, reaction of hexamethylenediamine with phosphorous acid and formaldehyde in molar ratio 1:2:2 yields [[(6-aminohexyl)imino]bis(methylene)]bisphosphonic acid (2b) which is isolated either as [[(6-carbobenzoxyaminohexyl)imino]bis](methylene)]bisphosphonic acid (3b) or as [[6-(N-benzoylamino)hexyl)imino]bis(methylene)]bisphosphonic acid (4b). Removal of the carbobenzoxy group with HBr from 3b or the benzoyl group with HCl from 4b gives pure [[(6-aminohexyl)imino]bis(methylene)]bisphosphonic acid (2b). All compounds were characterized by ¹³C NMR, ³¹P NMR and elemental analysis.     

Homopolymerization of Methyl Methacrylate by Novel Ziegler‐Natta‐Type Catalysts Based on Bis(chelate)‐nickel(II) Complexes and Methylaluminoxane

Novel catalytic systems based on bis‐(chelate)nickel(II) precursors, such as bis(α‐nitroacetophenonate)nickel(II) [Ni(naph)₂] and bis(2,6‐diisopropylbenzenesalicylaldiminate)nickel(II) [Ni(dipbs)₂], and methylaluminoxane (MAO) as the cocatalyst were employed for the polymerization of methyl methacrylate (MMA). Reaction parameters were examined. Under proper conditions, the Ni(dipbs)₂/MAO system allowed to obtain poly(MMA) with a very high productivity (TOF up to 70 000 h^–1) and a remarkable syndiospecificity degree (rr > 80%) at room temperature without addition of an ancillary Lewis base.     

Synthesis,crystal structure and magnetic properties of an oxamato-bridged heterobinuclear NiIICuII complex [Ni(cyclam)Cu(opba)]2·3DMSO

An oxamato-bridged heterobinuclear Ni^IICu^II complex [Ni(cyclam)Cu(opba)]₂ · 3DMSO (1) has been synthesized, characterized by elemental analysis, infrared spectra and magnetic susceptibility, where cyclam is 1, 4, 8, 11-tetraazacyclotetradecane and opba is o-phenylenebis(oxamato). The complex crystallizes in the triclinic system, space group P 1 with a = 12.006(3) Å, b = 12.783(3) Å, c = 20.977(5) Å, α = 76.634(4)°, β = 75.172(4)°, γ = 80.818(4)° and Z = 2. According to X-ray crystallographic studies, the four-coordinate copper(II) atom is a slightly distorted planar geometry and is linked to nickel(II) through the exo-cis oxygen atoms of [Cu(opba)]^2?; the six-coordinate nickel(II) center lies in a highly distorted octahedral environment. Magnetic susceptibility measurements of the complex in the temperature range 2–300 K indicate that the heterobinuclear Ni^IICu^II units are coupled antiferromagnetically with J = ?57.38 cm^?1, g _Ni = 2.25 and g _Cu = 2.02.