Cyclic ions in the mass spectra of trimethylsilyl derivatives of substituted o-dihydroxybenzenes

The mass spectra of trimethylsilyl (TMS) ethers/methyl esters of phenolic acids containing o-dihydroxybenzene groups have base peaks at [M?119]⁺ instead of the usual [M?15]⁺ and [M?31]⁺ that are characteristic of TMS/methyl esters of monohydroxyphenolic acids. These ions, formed by the loss of 31+88 u from the parent ion, possess a cyclic moiety as proven by substitution of deuterium atoms for hydrogen atoms in the TMS groups of the methyl esters of 3,4,5-trihydroxybenzoic (gallic), 3,4-dihydroxybenzoic (protocatechuic) and β-(3,4-dihydroxyphenyl)propenoic (caffeic) acids. Although these cyclic ions are the base peaks in TMS-derivatized o-dihydroxyphenolic acid esters, similar ions represent intense peaks but not necessarily the base peak in other derivatized compounds such as 1,2-dihydroxybenzene, 1,2-dihydroxy-3-methyl- and 1,2-dihydroxy-4-methyl-benzenes and flavan-3-ols that possess o-dihydroxybenzene groups. Compounds possession m- or p-dihydroxybenzene groups do not form these cyclic ions; therefore, this procedure for derivatization and interpretation of mass spectra is valuable for the identification of compounds containing o-dihydroxybenzene groups in complex mixtures of isomeric compounds.     

Syntheses and Characterization of Half—Sandwich Zirconium Complexes with Dichalcogenolate o—Carborane Ligands

Metallocene complex Cp2^ttZrCl2(Cp^tt=η^5-1,3-^tBu2C5H3)(1)has been prepared from the reaction of LiCp^tt with ZrCl4 in good yield.Reactions of 1 with dilithium dichalcogenolate o-carboranes afforded new type of half-sandwich compounds with dichalcogenolate o-carboranyl ligands,[Li(THF)4][Cp^ttZr(E2C2B10H10)2](E=S,2a;E=Se,2b)in which only one cyclopentadienyl ring ligand existed.Complexes 1 and 2a were structurally characterized by X-ray analyses.In complex 2a,the Zr(IV)ion is η^5-bound to one 1,3-ditert-cyclopentadienyl ring and σ-bound to four μ2-sulfur atoms of two dithio-carboranes.the zirconium atom and four sulfur atoms form a distorted pyramid.The coordination sphere around the zirconium atom resembles in a piano stool structure with four legs of sulfur stoms and the fulcrum at the zirconium stom.     

Unusual coordination in a silver thionate complex. Synthesis,structural characterization and theoretical calculations of dinuclear and polynuclear silver(I) thiosaccharinates with pyridine and 1,10-phenanthroline

Treatment of Ag₆(tsac)₆ (tsac = thiosaccharinate anion) with pyridine (py) and 1,10-phenanthroline (o-phen) each affords two novel silver(I)-thiosaccharinate complexes: dinuclear [Ag₂(tsac)₂py] (1) and polynuclear [Ag(tsac)(o-phen)]_n (2). Both crystal structures have been determined by X-ray diffraction and spectroscopic structural analysis (IR and Raman, UV–Vis, ¹H and ¹³C NMR) have also been made for both compounds. Thermal stability analysis (TGA and DTA) of complex 1 are used to confirm the strength of the pyridine coordination to the silver ion. The molecular structure of complex 1 shows some astonishing characteristics. The two silver atoms are in different environments: one of them is surrounded by two S atoms, while the other completes its coordination sphere by three N atoms, two from the thiosaccharinate anions and the third from a pyridine molecule. The short Ag(1)–Ag(2) contact distance, 2.9681(8) Å, indicates an interaction between the two silver metal atoms exists. Complex 2 shows a thiosaccharinate molecule bridging two silver atoms through the exocyclic S atom while the o-phenanthroline ligand is coordinated as a bidentate N,N chelate, forming a polynuclear chain. Quantum chemical calculations confirm the argentophilic character of the Ag–Ag interaction in complex 1, and its structure and vibrational assignments were correlated and confirmed theoretically.     

稀土配合物[Nd(o-NO2-C6H4COO)3(DMF)2]2的合成及其晶体结构

合成了一种新的双核倒反中心的稀土钕配合物[Nd(o-NO₂-C₆H₄COO)₃(DMF)₂]₂. 通过元素分析, 核磁共振谱和红外光谱对配合物的组成和结构进行了表征, 用热重分析研究了该配合物的热稳定性, 用X射线单晶衍射法测定了其晶体的结构. 钕配合物[Nd(o- NO₂-C₆H₄COO)₃(DMF)₂]₂晶体属三斜晶系, 空间群P-1, 晶胞参数a＝1.18652(12) nm, b＝1.24784(13) nm, c＝1.29958(13) nm, α＝64.220 (1)°, β＝66.306 (1)°, γ＝71.825 (1)°, V＝1.5645 (3) nm³, D_c＝2.167 mg/m³, Z＝2, μ＝3.415 mm^－1, F(000)＝986. 配合物中每个Nd(Ш)被4个邻硝基苯甲酸根桥联, Nd(Ш)的配位数为8, 配位原子分别来自于5个邻硝基苯甲酸羧酸根的6个氧原子和2个DMF的羰基氧原子. 配合物中的氢键和π…π 堆积作用使其成为三维立体结构. 同时发现了标题配合物固体具有光致发光现象, 发光性能测试表明该配合物具有很好的荧光性质.     

Spectrométrie de Masse d'Hétérocycles Azotés. VIII–Comportement sous l'Impact Electronique de Nitroarylazoles

The mass spectra of nitrophenylimidazoles and nitrophenylpyrazoles have been examined in order to establish whether neighbouring ortho-ortho′ substituents have an appreciable influence on the fragmentation patterns. For compounds having an ortho nitro group on the heterocycle, specific effects are observed. Isotope effects observed with deuterated derivatives confirm this and establish that in the case of o-nitroimidazoles the 2-H proton adjacent to both nitrogen atoms is involved in the loss of OH. Fragmentation of each compound is specific and study could eventually provide a satisfactory means for structure determination.     

An oxovanadium(IV) complex with o-vanillin-valine Schiff base and 1,10-phenanthroline ligands: synthesis,crystal structure and DNA interactions

A new mixed-ligand V(IV) complex, [VO(o-Van-Val)(phen)]·CH₃CN (o-Van-val = Schiff base derived from o-vanillin and l-valine, phen = 1,10-phenanthroline), was synthesized and characterized by physico-chemical methods and single-crystal X-ray diffraction. In the crystal, the V(IV) atom is six-coordinated by one oxo ligand, two oxygen atoms and one nitrogen atom from a valine Schiff base ligand, and two nitrogen atoms from 1,10-phenanthroline, giving a distorted octahedral arrangement. The DNA-binding properties of the complex were investigated by spectroscopic methods and viscosity measurements. The results suggest that the oxovanadium(IV) complex binds to DNA in an intercalation mode.     

Neuartige Isomeriefälle bei 1:2-CrIII- und CoIII-Komplexen von o,o'-Dihydroxyazoverbindungen: Pyramidal gebundener Stickstoff mit hoher Inversionsbarriere?

From the dimensions described in previously known X-ray structure analyses and from NMR.-spectroscopical datas of a 1:2 Co^III complex it is concluded that metal chelates of two and tri-dentated azo compounds are present in the diketo or quinone mono hydrazone form, provided that such a form is possible. As the metal atoms replaces the hydrazone proton the coordinating nitrogen atom can be predetermined. For the first time in the case of 1:2 Cr complexes from o,o'-dihydroxy azo compounds small amounts of byproducts have been observed which have the empirical composition of the main complexes. As the coordinated nitrogen atom is sp³-hybridized, its three bonds should be arranged in a pyramidal form. Therefore the ligands should be slightly bent. In the 1:2 Cr complexes where two of these ligands are coordinated to the metal atom perpendicularly to each other (Drew-Pfitzner-arrangement) 3 conformers (+ 3 mirror images) are possible. These conformers are ascribed to one group of the observed isomeric complexes. For another group it is supposed that at least one ligand is coordinated in the plane azo form. The postulated thrice bonded nitrogen atom possesses the requirements for a high inversion barrier: it is a member of two ortho condensed rings; moreover, it is bound to a Lewis acid. No such system seems to have been described, but in some published X-ray structure analyses, there is evidence to be found of its existence.     

Coordination-Modulated Metal Tetrathiafulvalene Octacarboxylate Frameworks for High-Performance Lithium-Ion Battery Anodes

Modulation of the ligands and coordination environment of metal–organic frameworks (MOFs) has been an effective and relatively unexplored avenue for improving the anode performance of lithium-ion batteries (LIBs). In this study, three MOFs are synthesized, namely, M₄(o-TTFOB)(bpm)₂(H₂O)₂ (where M is Mn, Zn, and Cd; o-H₈TTFOB is ortho-tetrathiafulvalene octabenzoate; and bpm is 2,2′-bipyrimidine), based on a new ligand o-H₈TTFOB with two adjacent carboxylates on one phenyl, which allows us to establish the impact of metal coordination on the performance of these MOFs as anode materials in LIBs. Mn-o-TTFOB and Zn-o-TTFOB, with two more uncoordinated oxygen atoms from o-TTFOB⁸⁻, show higher reversible specific capacities of 1249 mAh g⁻¹ and 1288 mAh g⁻¹ under 200 mA g⁻¹ after full activation. In contrast, Cd-o-TTFOB shows a reversible capacity of 448 mAh g⁻¹ under the same condition due to the lack of uncoordinated oxygen atoms. Crystal structure analysis, cyclic voltammetry measurements of the half-cell configurations, and density functional theory calculations have been performed to explain the lithium storage mechanism, diffusion kinetics, and structure-function relationship. This study demonstrates the advantages of MOFs with high designability in the fabrication of LIBs.     

Syntheses,crystal structures and characterization of divalent transition metal sulfonate complexes with O-phenanthroline

Two new complexes, [Zn(phen)₂(H₂O)₂]2L·H₂O (1) and [Cu(phen)(L)(H₂O)₂]L·3H₂O (2), where HL?= 4-aminobenzenesulfonic acid and phen = o-phenanthroline, have been synthesized and their crystal structures determined by X-ray diffraction. In the complexes the Cu(II) and Zn(II) atoms revealed two different coordination environments. Complex 1 consists of a cation [Zn(phen)₂(H₂O)₂]²⁺, in which Zn(II) is six-coordinated by four nitrogen atoms from two o-phenanthroline molecules and by two water molecules. Complex 2 has two crystallographically unique Cu(II) ions, where Cu(II) ion is five-coordinate with two nitrogen atoms of o-phenanthroline, two water molecules and one sulfonate oxygen atom. The electrochemical behavior and FT-IR of the two compounds have also been studied in detail.     

Structural Variations and Molecular Dynamics of Rare‐Earth Metal Complexes with the N,N‐Bis(2‐{pyrid‐2‐yl}ethyl)hydroxylaminato Ligand

The reaction of the donor‐functionalised N,N‐bis(2‐{pyrid‐2‐yl}ethyl)hydroxylamine and [LnCp₃] (Cp=cyclopentadiene) resulted in the formation of bis(cyclopentadienyl) hydroxylaminato rare‐earth metal complexes of the general constitution [Ln(C₅H₅)₂{ON(C₂H₄‐o‐Py)₂}] (Py= pyridyl) with Ln=Lu ( 1 ), Y ( 2 ), Ho ( 3 ), Sm ( 4 ), Nd ( 5 ), Pr ( 6 ), La ( 7 ). These compounds were characterised by elemental analysis, mass spectrometry, NMR spectroscopy (for compounds 1 , 2 , 4 and 7 ) and single‐crystal X‐ray diffraction experiments. The complexes exhibit three different aggregation modes and binding motifs in the solid state. The late rare‐earth metal atoms (Lu, Y, Ho and Sm) form monomeric complexes of the formula [Ln(C₅H₅)₂{η²‐ON(C₂H₄‐η¹‐o‐Py)(C₂H₄‐o‐Py)}] ( 1 – 4 , respectively), in which one of the pyridyl nitrogen donor atoms is bonded to the metal atom in addition to the side‐on coordinating hydroxylaminato unit. The larger Nd³⁺ and Pr³⁺ ions in 5 and 6 make the hydroxylaminato unit capable of dimerising through the oxygen atoms. This leads to the dimeric complexes [(Ln(C₅H₅)₂{μ‐η¹:η²‐ON(C₂H₄‐o‐Py)₂})₂] without metal–pyridine bonds. Compound 7 exhibits a dimeric coordination mode similar to the complexes 5 and 6 , but, in addition, two pyridyl functions coordinate to the lanthanum atoms leading to the [(La(C₅H₅)₂{ON(C₂H₄‐o‐Py)}{μ‐η¹:η²‐ON(C₂H₄‐η¹‐o‐Py)})₂] complex. The aggregation trend is directly related to the size of the metal ions. The complexes with coordinative pyridine–metal bonds show highly dynamic behaviour in solution. The two pyridine nitrogen atoms rapidly change their coordination to the metal atom at ambient temperature. Variable‐temperature (VT) NMR experiments showed that this dynamic exchange can be frozen on the NMR timescale.     

The photochromic behaviour of two viologen salts modulated by the distances between the halide anions and the cationic N atoms of viologen

In recent years, viologens and their derivatives have received much attention due to their various potential applications, ranging from electro‐ or photochromic devices to clean energy. Generally, viologen compounds exhibit a colour change upon being subjected to an external stimulus. However, the chromic mechanism is still ambiguous, because there are many electron‐transfer pathways for a chromic compound that need to be considered. Thus, exploring new chromic viologen‐based compounds with one pathway should be important and meaningful. In this article, two new viologen‐based derivatives, namely 1‐(2‐cyanobenzyl)‐4,4′‐bipyridinium chloride (o‐CBbpy·Cl), C₁₈H₁₄N₃⁺·Cl^? ( 1 ), and 1‐(2‐cyanobenzyl)‐4,4′‐bipyridinium bromide (o‐CBbpy·Br), C₁₈H₁₄N₃⁺·Br^? ( 2 ), have been synthesized and characterized. Interestingly, both isomorphic compounds possess only one electron‐transfer pathway, in which 1‐(2‐cyanobenzyl)‐4,4′‐bipyridinium cations (o‐CBbpy) and halide anions are employed as electron donors and acceptors, respectively. Salts 1 and 2 consist of o‐CBbpy cations involved in π–π interactions and hydrogen‐bond interactions, and halide anions weakly hydrogen bonded to the viologen cations. The salts show different photoresponsive characteristics under identical conditions, which should be mainly related to the distances between the halide cations and the cationic N atoms of o‐CBbpy but not the electronegativities of the halogen atoms. These results should not only help in understanding that the distance of the electron‐transfer pathway plays an important role in viologen‐based photochromism, but should also guide the design and synthesis of additional photochromic materials.     

Syntheses,crystal structures and electrochemistry of divalent metal 4-methylbenzenesulfonate complexes with o-phenanthroline

Three new compounds, namely [Mn(phen)₂(L)₂] · EtOH (1), [Zn(phen)₂(H₂O)₂]2L · 6H₂O (2) and [Cd(phen)₂(H₂O)₂]2L · 6H₂O (3), where HL = 4-methylbenzenesulfonic acid and phen = o-phenanthroline, have been synthesized, and their crystal structures determined by X-ray diffraction. In the complexes the metal atoms have two different coordination environments. Complex (1) consists of neutral molecules, [Mn(phen)₂(L)₂], in which Mn^II is six-coordinated by four nitrogen atoms from two o-phenanthroline molecules and two oxygen atoms from two sulfonate ions. Complexes (2) and (3) are isomorphous, each consisting of cationic species [M(phen)₂(H₂O)₂]²⁺ [M = Zn (2), Cd (3)], in which M^II is six-coordinated by four nitrogen atoms from two o-phenanthroline molecules and two water molecules. The electrochemical behavior and FT-IR of these compounds were also studied in detail.     

Recent Progress in the Development of Solid-State Luminescent o-Carboranes with Stimuli Responsivity

o-Carborane, a cluster compound containing boron and adjacent carbon atoms, displays intriguing luminescent properties. Recently, compounds containing o-carborane units were found to show suppressed aggregation-induced quenching and intense solid-state emission; they also show potential for the development of stimuli-responsive luminochromic materials. In this Minireview, we introduce three kinds of fundamental photochemical properties: aggregation-induced emission, twisted intramolecular charge transfer in crystals, and environment-sensitive excimer formation in solids. Based on these properties, several types of luminochromism, such as thermos-, vapo-, and mechanochromism, have been discovered. Based mainly on results from recent studies, we illustrate these mechanisms as well as unique luminescent behaviors of o-carborane derivatives.     

Synthesis ofo-andm-carborane derivatives of [2,2]paracyclophane and abnormal Clemmensen reduction of ketones of the [2,2]paracyclophane and carborane series

Methods for the synthesis of [2,2]paracyclophane derivatives containingo- andm-carboranyl substituents in position 4, separated from the [2,2]paracyclophane system by one or two C atoms (alcohols and ketones) were developed. The Clemmensen reduction of a number of ketones of the [2,2]paracyclophane ando-carbonane series occurs abnormally. The reduction of 1-benzoyl-o-carboranes to the corresponding alcohols by zinc in ethanol in a neutral medium was performed for the first time. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1206–1211, June, 1997.     

Synthesis of 3-amino-3,4-dihydro-2(1H)-quinazolinones as potential anticonvulsants

Thirteen 3-amino-3,4-dihydro-2(1H)-quinazolinones have been synthesized from ethyl chloroformate and o-aminobenzylhydrazines. The latter compounds were obtained from the metal hydride reduction of either o-aminobenzhydrazides or o-acylaniline hydrazones. All compounds were evaluated in mice in the maximal electroshock (MES) seizure and pentylenetetrazole (sc Met) seizure threshold tests for anticonvulsant activity and in the rotorod test to determine neurotoxicity. Five of the compounds showed activity in one or both tests at a dose of 300 mg/kg or lower. The most active compound is 3-dimethylamino-3,4-dihydro-2(1H)-quinazolinone.     

A Novel Silver（Ⅰ）σ -Complex Supramolecular Polymer： [Ag2（o-HOPhCO2）2]n

The hydrothermal reactions of sodium o‐hydroxybenzoate with AgNO₃ yield a novel stable Ag(I) s?‐complex supramolecular polymer, [Ag₂(o‐HOPhCO₂)₂]_n. The structure of [Ag₂(o‐HOPhCO₂)₂] was solved by single crystal X‐ray diffraction analysis. It is monoclinic with space group P2Jc and unit cell parameters a=0.7394(2) nm, b= 0.8822(2) nm, c=1.0662(2) nm, β= 107.66(3)°, Z=4. The silver(I) atom is two‐coordinated by two carboxylic oxygen atoms of two o‐hydroxybenzoate ligands, and meanwhile, forms supramolecular interaction with one carbon atom of phenyl‐ring in the third o‐hydroxybenzoate group. The a‐form Ag…C supramolecular bond bridges [Ag₂(o‐HOPhCO₂)₂] units into an infinite 2D layered polymer [Ag₂(o‐HOPhCO₂)₂]_n. The coordination sphere of the silver atom is best described as a distorted T‐shaped geometry.     

New potentially tridentate amidinate ligand {o-MeOC6H4NC(Ph)N(SiMe3)}?. Synthesis and molecular structures of amidinate complexes of lithium [{o-MeOC6H4NC(Ph)N(SiMe3)}Li]2 and yttrium [{o-MeOC6H4NC(Ph)N(SiMe3)}YCl2(THF)2]2

The reaction of lithium silylamide [??o-MeOC₆H₄N(SiMe₃)}Li(OEt₂)]₂ with 2 equiv. of benzonitrile in THF at ??20 °C affords the lithium derivative of the new tridentate amidinate ligand [{o-MeOC₆H₄NC(Ph)N(SiMe₃)}Li]₂. The X-ray diffraction study showed that this complex has a dimeric structure due to the coordination of the N atoms and the ether group of one amidinate ligand to different Li atoms. The reaction of anhydrous YCl₃ with the resulting complex in THF gives the monoamidinate complex [{o-MeOC₆H₄NC(Ph)N(SiMe₃)}YCl₂(THF)₂]₂ regardless of the reagent ratio. The latter has a dimeric structure in the crystalline state as a result of the presence of two ??₂-bridging Cl atoms that link Y atoms. The ether groups of the amidinate ligands are not involved in the metal-ligand interaction.     

DFT study of bridge atom dependence of absorption and emitting wavelength of tridentate ligand chelates of aluminum

The energy band structures of two promising organic light‐emitting compounds, Al(Saph‐q) [(salicylidene‐o‐aminophenolato) (8‐quinolinoato) aluminum] and Al(azb‐q) [(o,o′‐dihydroxyazobenzene) (8‐quinolinoato)aluminum], were investigated using the approaches of density functional theory (DFT) at the B3LYP/ 6‐31G*//3‐21G* level, and the projected density of states (PDOS). The predicted maximum absorption wavelengths, 392 nm for Al(Saph‐q) and 496 nm for Al(azb‐q), were in good agreement with the experimentally determined, 420 nm and 504 nm. The different bridge atoms make considerable varieties of the frontier orbitals. The results were reasonably expounded via a detailed analysis of the electronic structure. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

Coordination isomerism of the complex of o-methoxybenzoyl chloride with tetrachlorostannane. The results of ab initio calculations

Quantum-chemical calculations of three isomers of the o-methoxybenzoyl chloride complex with tetrachlorostannane and of their components were performed applying the RHF/3-21G* and MP2/3-21G* methods. It was found that a complex with trigonal-bipyramidal structure is formed, its formation occurred through the interaction of ester (not carbonyl) oxygen atom with tin atom. This complex eventually is transformed into the energetically more favorable cis-octahedral complex of the same composition. The tin atom in the latter complex interacts with two oxygen atoms. The reasons for the formation of energetically unfavorable complex of trigonal-bipyramidal structure is the almost equal probability of the existence of various possible forms of o-methoxybenzoyl chloride and therefore higher probability of the Sn atom to interact with the ester oxygen atom possessing a much more negative charge than the carbonyl oxygen.