Complexation Studies of Phosphorus Containing Bis and Tris (Benzocrown Ether) Moieties

The complexation behaviour between salts of Li⁺-Rb⁺ in CD₃CN and tris(benzocrown ether)s 2a,bX=P(NMeN=CH-B15C5)₃ (X = O, S) and tri[bis(benzocrown ether)][N=P(NMeN=CH-B15C5)₂]₃ 3 was investigated by ¹³ C NMR spectroscopy. Using the program RMNSTAB, the complexation constants for the different possible complexes (M₂L, ML andML₂ were L represents one benzo-15-crown-5) were obtained and were compared with those of the corresponding monomer material. A remarkable ``biscrown effect' for compounds 2a,b and 3 was found, especially for potassium and rubidium by the predominant formation of stable ML₂ complexes. The strong chelate effect make these ligands highly efficient extracting agents for alkali metal picrate salts of K⁺, Rb⁺ and Cs⁺,as shown by UV-Vis spectroscopy.     

THE BEHAVIOR OF RIGID AND SEMI-RIGID BIDENTATE DONOR MOLECULES TOWARD SOME SIMPLE BORON ACCEPTORS

Abstract

Synthesis of a series of complexes of the type LLBX₂ ⁺ BX₄ ^? where X = F^? and CI^? and LL = 1,10-phenanthroline, 2,2′-bipyridine and 1,8-bis(dimethylamino)naphthalene was achieved by the direct interaction of the ligand and BX₃. No reaction was observed for X = CH₃. The reactions provide a direct route for the preparation of tetra-coordinate boronium cations. The boron-11 nmr and infrared spectra of these complexes confirm the ionic nature of the compounds. 2,2′-Bipyridine functions as a chelating agent rather than as a bis-monodentate donor. 1,8-Bis(dimethylamino)naphthalene is found to be able to chelate cations much larger than protons. The steric implications of donor-acceptor interactions of boron with rigid and semi-rigid chelating donor molecules are discussed.     

On the metal ion selectivity of PNP-lariat ether—an insight from density functional theory calculations

The complexes of Li⁺, Na⁺, K⁺, Be²⁺, Mg²⁺, and Ca²⁺ metal cations with [N₃P₃R₄O(CH₂CH₂O)₄] (R?=?H(1), NMe₂(2), NC(NMe₂)₂(3)) PNP-lariat ethers were systematically studied in the gas phase by using density functional theory (DFT) B3LYP-D3/6-311+G(3df,2p)//B3LYP/6-31+G(d,p) method. The gas phase cation affinities were calculated to span the wide range between 64.2 and 496.1 kcal mol^?1 in order K⁺?<?Na⁺?<?Li⁺?<?Ca²⁺?<?Mg²⁺?<?Be²⁺. The structural and electronic properties of 1–3 and their complexes were investigated and effects of electron-donor substituents were analyzed. The electron-donor substituents were found to promote the cation affinity. Sidearm coordinative interaction with the crown ether-complexed metal ion has been noticed. The nature of the metal–ligand interactions was investigated using Bader’s Quantum theory of atoms in molecule. It has been found that the Be²⁺–N bonds are partly covalent in nature while other coordinate bonds are of the electrostatic nature. The electron density at the bond critical points was found to be consistent with cation affinity. Natural bond orbital analysis was performed on the optimized geometries. The results showed that the stabilization interaction energies are caused by the donation of O/N lone pair electrons to the LP* orbitals of the metal cations. The amount of charge transfer follows the cation affinity order. The largest charge transfer and associated second-order perturbation stabilization energy were observed for Be²⁺ complexes.

     

THEORETICAL COMPARISON OF THE BONDING OF CHALCOCARBONYL LIGANDS

Abstract

Fenske-Hall molecular orbital calculations on the complexes CpFe(CO)₂(CX)⁺ (X = O, S, Se, and Te) have been used to quantify the nature of bonding between the CX ligands and the metal atom. In addition, conclusions have been reached about the reactivity of the complexes under both nucleophilic and electrophilic attack. The previously established trend of increasing metal—ligand bond strength as X changes from O to S to Se is demonstrated by our molecular orbital calculations, and found to extend to Te. The mechanism for nucleophilic attack, variously explained in the past by either charge control or orbital control, is quantitatively ascribed to orbital control only. The nature of electrophilic attack on these complexes is also found to begin with orbital control.     

Metastable ion study of substituted cyclopentadienylmanganese cations in the gas phase

The behavior of some substituted cyclopentadienylmanganese ions has been studied by tandem mass spectrometry. This metastable ion study showed that only C₅H₅Mn⁺ and (C₅H₄CN)Mn⁺ ions retain their nido-cluster structure (1), which is characterized by a simple metal-ligand bond cleavage. Other substituted ions, RXC₅H₄Mn⁺, rearrange to a different extent, depending on the nature of the substituent. The first rearrangement step is R radical migration to the central metal atom, leading to RMnC₅H₄X⁺-type ions (2). These ions decompose by elimination of X (for X=CO) or with formation of RMnX⁺, but further rearrangements can also occur. These are the reverse migration of R from the metal atom to the π-ligand (for R=H, Ph) and cyclopentadienyl ring expansion (for X=CH₂). Collisional activation mass spectra contained an Mn⁺ ion peak, which can indicate the existence of stable type 1 structures for most cyclopentadienylmanganese ions. Carboxyl and hydroxymethyl derivatives exist, presumably as ions of type 2. The neutralization-reionization mass spectra of RXC₅H₄Mn⁺ ions are also discussed.     

Can five-membered Te<Subscript>2</Subscript>N<Subscript>2</Subscript>S rings be considered aromatic?

The structures and molecular properties of three cyclic tellurium species [Te₂N₂S]²⁺ (1 ²⁺ ), [Te₂N₂SCl]⁺ (1 ⁺ ), and Te₂N₂SCl₂ (1) were studied using Density Functional Theory (DFT) with the aim of analyzing and quantifying the degree of electron delocalization in the rings. The structural data for the AsF₆⁻ salt of the cation 1 ⁺ , as well as the experimental vibrational frequencies of 1 and 1 ⁺ , were compared to calculated structures and vibrational modes. While only the five-membered ring of 1 ²⁺ obeys the classic Hückel aromaticity criteria, reflected in the nature of the π orbitals and natural resonance structures, all the three species are magnetic aromatic according to nucleus-independent chemical shift (NICS). However, the out-of-plane component of the NICS tensor (NICS_zz) is able to provide a reliable characterization of the π aromatic character, by showing that successive binding of two chlorine atoms to the same tellurium atom disrupts the π electron delocalization, and that total NICS cannot always be trusted as an aromaticity indicator.     

Reactivity of [Mo(NHNRPh)(NNRPh)(acac)X2] (R=Ph,Me; X=Br,I) toward tertiary phosphines

The reactivity of mixed [organohydrazido(1-)][organohydrazido(2-)]molybdenum(VI) complexes [Mo(NHNRPh)(NNRPh)(acac)X₂] {R?=?Ph, X?=?Br (1); R?=?Ph, X?=?I (2) and R?=?Me; X?=?I (3)} with tertiary phosphines as PPh₃, PMePh₂ and PMe₂Ph are examined. The syntheses of [Mo(NNPh₂)₂Br₂(PPh₃)] (4), [Mo(NNPh₂)₂Br₂(PMePh₂)₂] (5), [Mo(NNPh₂)₂Br₂(PMe₂Ph)₂] (6), [Mo(NNPh₂)₂(acac)I(PPh₃)] (7), [Mo(NNPh₂)₂(acac)(PMePh₂)₂]⁺I^? (8) and [Mo(NNMePh)₂(acac)(PMePh₂)₂]⁺I^? (9) are reported. All complexes were characterized by elemental analysis, UV-visible, IR, ¹H and ³¹P{H} NMR spectroscopy.     

Laser-induced fluorescence detection of N+2(X 2Σ+g) resulting from the He(23S) + N2 and He+, He+2 + N2 reactions in a flowing afterglow

The formation processes of N⁺₂ (X ²Σ⁺_g) resulting from the He(2 ³S) + N₂ Penning ionization and the thermal energy He⁺, He⁺₂ + N₂ charge transfer reaction are studied by observing the N⁺₂ (B ²Σ⁺_u ← X ²Σ⁺_g) laser-induced fluorescence (LIF) in a flowing afterglow. In both reactions, the vibrational population) decrease monotonically with increasing vibrational quantum number from υ″ = 0 to 3, and a population inversion with a peak at υ″ = 4 is seen. In the He(2 ³S) + N₂ Penning ionization, the vibrational populations of N⁺₂ (X, υ″ = 0–2) are explained by a direct channel and the B —X radiative cascade, while those of N⁺₂ (X, υ″ = 4–6) are ascribed to the collision-induced electronic energy transfer between the A ²Π_u and X ²Σ⁺_g states. In the He⁺, He⁺₂ + N₂ reaction, the N⁺₂ (X, υ″ = 0–3) is interpreted as the B−X radiative cascade and the collisional quenching of the unidentified states produced from the He⁺ + N₂ reaction, while the collision-induced electronic energy transfer from the N⁺₂ (A) state produced through the He⁺₂ + N₂ reaction is probably important for the formation of N⁺₂ (X, υ″ = 4–6).     

A theoretical study of the activation of methane by Gold(III) homoleptic complexes

The density functional theory method with the PBE functional, SBK pseudopotential, and extended basis sets was used to study the reaction between methane and gold(III) homoleptic complexes, namely, [AuX₄]^? (X = Cl, Br, I, H, CN, NH₂, OH, CH₃, and SH), [Au(X(CY)₂X)₂]^? (X = S, Y = H; X = Y = O), Au₂Cl₆, [Au(X₂(CY))₂]⁺ (X = S, Y = NH₂; X = O, Y = H), and [Au(acac)₂]⁺, with the formation of electrophic substitution products. The activation of methane under mild conditions was found to be uncharacteristic of anionic and neutral complexes. According to calculations of cationic oxygen-containing complexes, the formation of methane complexes is possible in their reactions with methane. The energy barrier to this reaction noticeably decreases because of the activation of the C-H bond in this complex. The heat effects vary widely depending on the nature of the ligand. There is, however, no obvious correlation between their values and the activation energy of the reaction.     

Synthesis,spectroscopic characterization and antibacterial sensitivity of some chloro dimethylsulfoxide/tetramethylenesulfoxide ruthenium(II) and ruthenium(III) complexes with 2-aminobenzothiazole

Synthesis and characterization of seven ruthenium(II) and ruthenium(III) complexes of sulfoxide with 2-aminobenzothiazole are reported. Three different formulations exist: [cis,cis,cis-RuCl₂(SO)₂(2-abtz)₂] and [trans,trans,trans-RuCl₂(SO)₂(2-abtz)₂] and [trans-RuCl₄(SO)(2-abtz)] ^? [X]⁺ (where SO?=?dimethyl sulfoxide (dmso) or tetramethylenesulfoxide (tmso); 2-abtz?=?2-aminobenzothiazole and [X]⁺?=?[H(abtz)]⁺, [Na⁺]. These complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibility, FTIR, ¹H NMR, ¹³C{¹H} NMR and electronic spectroscopy. Some of the complexes were screened for their antibacterial activity and are found to be potent against the gram negative bacteria Escherichia coli.     

Novel Properties of Iodophosphonium Ions: Kinetically Labile Behaviour and Secondary Bonding

Abstract

Neutral species R₃PX₂ in equilibria with halogenophosphonium halides R₃PX⁺X^? do not always contain hypervalent phosphorus (10-P-5)! Iodophosphonium ions R₃PI⁺ show R₃P-I… X interaction in many cases, leading to hypervalent iodine (10-I-2). Evidence for secondary IX bonds is provided by n.m.r. spectra and X-ray crystal structure determinations.     

Isolation of [Rh(diolefin)X2]- species and their reactions with P- or N-donor ligands,tin(II) halides and carbon monoxide

Anionic [Rh(diolefin)X₂]⁻ species (X = Cl, Br) have been prepared and their reactions studied. The reactions with monodentate ligands led to neutral tetracoordinated complexes, and with N-donor bidentate ligands (Rh : LL = 2 : 1) gave Rh(X)(diolefin)(LL), [Rh(diolefin)(LL)]⁺[Rh(diolefin)X₂]⁻, or [Rh(diolefin)(LL)]X compounds, depending on the nature of LL or X. Reactions with carbon monoxide involved diolefin displacement. A trichlorostannato complex was obtained from the [Rh(COD)Cl₂]⁻ species. Reactions of [Rh(COD)Br]₂ with bidentate N-donor ligands were also studied.     

Syntheses,characterization of and studies on the electrochemical behaviour of ferrocenyl dithiophosphonates and 4-methoxyphenyl dithiophosphonates

Some 1,3-dithiadiphosphetane 2,4-disulfides (X₂P₂S₄, X: Fc, FcLR; X: CH₃O?C₆H₄?, LR) were allowed to react with alcohols to obtain dithiophosphonic acids (X(OR)PS₂H). These were converted to the corresponding ammonium salts. The salts were of the structures [Fc(OR)PS₂]^?[NH₄]⁺, R: 3-methyl-1-butyl- for I; 1-phenyl-1-propyl- for II; 3-pentyl- for III; 3-phenyl-1-propyl- for IV and [CH₃O?C₆H₄(OR)PS₂]^?[NH₄]⁺, R: 3-methyl-1-butyl- for V and 1-phenyl-1-propyl- for VI. To the best of our knowledge, all the compounds except V were prepared for the first time.

The compounds synthesized were characterized by elemental analysis, NMR (¹H, ¹³C, ³¹P), MS, FTIR, and Raman spectroscopies. Electrochemical behaviors of I–VI at disposable pencil graphite electrode (PGE) were investigated by using cyclic voltammetry (CV) and square-wave voltammetry (SWV). Adsorption and diffusion patterns of all the compounds on the PGE were also studied.

Two electroactive groups were identified in the compounds I–IV and only one in V and VI. The ferrocenyl groups of I-IV were oxidized at around 0.4 V. The same compounds display a second, more intense CV band at 0.8 V. The corresponding band for the compounds V–VI appears at around 0.6 V with a much weaker intensity. It is suggested that the ferrocenyl group introduced into the structures stabilizes the radical species formed as the product of the oxidation of the dithiophosphonato group.     

Synthesis of Mixed Thiuram Disulfides

Abstract

Tris(aminomethyl)phosphines and their oxides form triacidic salts that, unlike the free bases, are air-stable and non-hygroscopic. The salts of the unsubstituted compounds, (NH₃ ⁺CH₂)₃ P(O)_n 3X^?(3b: n = O, X = Br; 4a-c: n = 1, X = Cl, Br, or I), may be prepared directly from 1,3,5-triaza-7-phosphaadamantane (1) or its oxide (2) or from tris(N-carbomethoxylaminomethyl)phosphine oxide (9) by hydrolysis with the appropriate acid. The behaviour of the compounds towards acids and nucleophilic reagents is discussed.     

Influence of ion-exchange and impregnation modification of zeolite X on its catalytic properties in the alkylation of toluene with methanol

The dependence of the activity and selectivity of ion-exchanged forms of zeolite X with incorporated cesium process in alkylation of toluene with methanol in the side chain on the nature of the ion-exchanged cations (Na⁺, Cs⁺, Mg²⁺, Zn²⁺) has been established. It is shown that introduction of Mg²⁺ and Zn²⁺ in combination with Cs₂CO₃ significantly increased the yields of ethylbenzene and styrene in comparison with their yields on alkali forms of zeolite X. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 33–38, January–February, 2006.     

Gas‐phase reactions of XH3+ (X = C,Si, Ge) with NF3: a comparative investigation on the detailed mechanistic aspects

The gas‐phase reaction of CH₃⁺ with NF₃ was investigated by ion trap mass spectrometry (ITMS). The observed products include NF₂⁺ and CH₂F⁺. Under the same experimental conditions, SiH₃⁺ reacts with NF₃ and forms up to six ionic products, namely (in order of decreasing efficiency) NF₂⁺, SiH₂F⁺, SiHF₂⁺, SiF⁺, SiHF⁺, and NHF⁺. The GeH₃⁺ cation is instead totally unreactive toward NF₃. The different reactivity of XH₃⁺ (X = C, Si, Ge) toward NF₃ has been rationalized by ab initio calculations performed at the MP2 and coupled cluster level of theory. In the reaction of both CH₃⁺ and SiH₃⁺, the kinetically relevant intermediate is the fluorine‐coordinated isomer H₃X‐F‐NF₂⁺ (X = C, Si). This species forms from the exoergic attack of XH₃⁺ to one of the F atoms of NF₃ and undergoes dissociation and isomerization processes which eventually result in the experimentally observed products. The nitrogen‐coordinated isomers H₃X‐NF₃⁺ (X = C, Si) were located as minimum‐energy structures but do not play an active role in the reaction mechanism. The inertness of GeH₃⁺ toward NF₃ is also explained by the endoergic character of the dissociation processes involving the H₃Ge‐F‐NF₂⁺ isomer. Copyright © 2009 John Wiley & Sons, Ltd.     

Alkali Metal- and Ammonium Picrate Extraction and Complex Forming Capabilities of d-Glucose and d-Mannose-based Lariat Ethers

The alkali metal- and ammonium picrate extracting ability of d-glucose- and d-mannose-based 15-crown-5 ethers and related lariat ethers was investigated in dichloromethane – water system. A heteroatom was waried in the crown ether containing a 4,6-O-benzylidene-α-d-glucopyranoside unit 6, (X=O), 2 (X=S) and 8a (X=NH). Extracting ability of the latter species (8a) was excellent (97–99%) in regard of all cations (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺ and NH₄⁺) examined, it was not, howewer, selective. Introduction of a side arm on the nitrogen atom of 8a decreased the extracting ability, but increased the selectivity. In this series of compounds (8b–f, 4), 4 with a pyridylethyl substituent allowed the extraction of sodium picrate in 72%. The glucose-based macrocycles 8a, 8e and 8f formed a stronger complex with the cations examined than the mannose-based analogues 9a, 9e and 9f, that can be explained by the all-gauche conformation of the former ones. It was pointed out that in the case of crowns with tertiary amine moieties, the basicity increases the quantity of the picrates extracted. According to complex forming measurements by FAB-MS, the best sodium ion selectivity was achieved by the γ-hydroxypropyl substituted lariat ether (8e). Possible structures of the complexes formed by the two types of monosacharides with sodium cation were evaluated by molecule modelling calculations.     

Halogen-Substituted Cyclotrigermenes: The π(Ge = Ge)-σ*(Ge–X) Interaction and a Unique Dynamic Behavior

Abstract

The halogen-substituted cyclotrigermenes (^tBu₃Si)₃Ge₃X (X = F, Cl, Br, I) (2) were synthesized by the reaction of tris(tri-tert-butylsilyl)cyclotrigermenylium tetrakis(2,3,5,6-tetrafluorophenyl)borate) (1 ⁺?TTFPB^?) with potassium halides (KF, KCl, KBr, KI). Intramolecular halogen migration over the three-membered ring skeleton was observed in the solution.

GRAPHICAL ABSTRACT     

Electron ionization mass spectra of novel 2,3:4,5-bis-O-(1-methylethylidene)-β-D-fructopyranose derivatives and related sugar sulfamates

The electron-impact (EI) mass spectral fragmentation of ten bis-O- (1-methylethylidene)fructopyranose derivatives and three related sugar sulfamates were investigated. In particular, 2,3:4,5-bis-O - (1-methylethylidene)-β-D-fructopyranose sulfamate (topiramate), a potent anticonvulsant, was examined in greater detail. The fragmentation of the 2,3:4,5-bis-O-(1-methylethylidene) fructopyranose derivatives in general was not very dependent on the nature of substitution; the mechanisms of the common and unique fragmentation patterns are presented. These compounds showed characteristic peaks at m/z [M – 15]⁺, [M – 15 – 58]⁺, [M – 15 – 58 – 60]⁺, [M ? CH₂X]⁺ and [M ? CH₂X – 58]⁺ where X = OSO₂NR₂ (R ? H, CH₃, and/or Ph), OC (O)NHR, NH₂, CI and OH. The fragmentation of isomeric bis-O-(1-methylethylidene) derivatives of aldopyranose, ketopyranose and ketofuranose sulfamates was also investigated. The results indicate that isomeric sugar sulfamates can be easily distinguished in the EI mode. Key fragmentation pathways are discussed for these compounds.     

Exploring the Anion–Cation Interaction in m‐Terphenyltetrafluorosilicates by Using Multinuclear NMR Spectroscopy,X‐ray Diffraction,and ICR‐FT‐MS

The synthesis of a series of m‐terphenyl‐substituted tetrafluorosilicates with different cations (Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Tl⁺) is described and the interactions between the anion and cation are investigated in the solid, solution, and gas states by using multinuclear NMR spectroscopy, X‐ray diffraction, and ion cyclotron resonance Fourier‐transform mass spectrometry (ICR‐FT‐MS). In solution, heteronuclear NMR spectroscopy parameters show only limited sensitivity to the nature of the cation, which furthermore can be affected by solvent effects. More pronounced effects are observed in the structural data obtained from X‐ray diffraction studies, which are in good agreement with experimental gas‐phase data from ESIMS. ESIMS also reveals the existence of dimeric species of the type [M(DmpSiF₄)₂]^? (Dmp=2,6‐dimesitylphenyl), the stability of which was determined by normalized collision energy experiments.