Halide Adducts Research Articles

Quantum-chemical study of adducts of germanium halides with nitrogen-containing donors

Structural and thermodynamic characteristics of adducts GeX4 · nL (n = 1, 2; X = F, Cl, Br; L = NH3, py, bipy, phen) have been calculated by the B3LYP density functional theory method. The enthalpies of sublimation of complexes trans-GeX4 · 2py and the adduct GeCl4 · bipy have been estimated for the first time. The rearrangement energies of the donor and acceptor fragments and the Ge-N bond energies for the 1:1 and 1:2 complexes have been calculated. While the rearrangement energy for germanium halides is lower by 19–63 kJ mol−1 than that for silicon halides, the energy of the donor-acceptor bond in the former case is slightly lower. As a result, germanium adducts are slightly more stable than silicon adducts.

Preparation of Geminal Donor-Acceptor Units by Reactions of Low Valent Metal Halides with Iminium Chlorides

Abstract The organogallium compound [{Me2NCH2Ga(Cl,I)2}2] (1) and the organoindium compounds [Me2NCH2In(Cl,Br)2]2 (2) and [Me2NCH2InCl2]2 (3) have been prepared by the reactions of the low valent metal halides “GaI”, InBr and InCl with the iminium salt [Me2N=CH2]Cl. Compounds 1 and 2 are heterohalogen mixtures. These compounds were characterised by NMR spectroscopy and mass spectrometry, 1 furthermore by single crystal X-ray diffraction and 3 by elemental analysis. During the work-up procedure, minor amounts of hydrogen halide adducts of compounds 2 and 3 were isolated as single crystals, which contain a further equivalent of THF. These zwitter-ionic species Me2N(H)CH2In(Br,Cl)3·THF (2·H(Cl,Br)·THF) and Me2N(H)CH2InCl3 ·THF (3 ·HCl ·THF) were identified by single crystal X-ray diffraction. Methylation reactions of compounds 1 and 2 with MeLi gave two well-established compounds [{Me2NCH2GaMe2}2] and [{Me2NCH2InMe2}2], which were obtained previously by different preparation procedures.

Equilibrium Partitioning Model Applied to RDX−Halide Adduct Formation in Electrospray Ionization Mass Spectrometry

An equilibrium partitioning model is applied for the first time to the sequential formation of 1:1 and then 2:1 adducts between the high explosive cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX) and halide anions fluoride, chloride, bromide, and iodide in electrospray ionization interface (ESI) mass spectrometry. The equilibrium partitioning model is developed and model calculations are presented to demonstrate the generic behavior of the system, which is in qualitative agreement with the observed changes in 1:1 (RDX-halide) and 2:1 (RDX-halide) responses in ESI-MS. The model is successfully applied to the experimental data with the use of octanol-water partitioning coefficients to predict interior-to-surface partitioning behavior of the complexes in droplets formed in the ESI. The data and model suggest that the significantly more hydrophobic 2:1 complexes are readily observed in ESI-MS, even though their formation constants may be several orders of magnitude less than that of the 1:1 complex. Structures for RDX-halide 1:1 and 2:1 complexes are proposed based on ion-dipole attractions and destabilizing dipole-dipole interactions.

Determination of Bond Dissociation Energies Using Electrospray Tandem Mass Spectrometry and a Derived Effective Reaction Path Length Approach

A new approach for calculating bond dissociation energies (BDEs) from ES-MS/MS measurements has been developed. The new method features a "derived effective reaction path length" that has been applied to measure BDEs of alkali metal (Li+) adducts and halide (Cl-) adducts of monoacylglycerol, 1,2-diacylglycerol, and 1,3-diacylglycerol lipids. Also studied were lithium-bound dimers of monoacylglycerols, 1,2-diacylglycerols, and 1,3-diacylglycerols. BDEs for the adducts and dimers of the lipids were derived from collision-induced dissociation experiments using a triple quadrupole mass spectrometer with electrospray as the ionization source. Mass spectral data were used to empirically derive a single-exponential growth equation that relates product cross section to collision energy. From these single-exponential equations, a general second-order polynomial was derived using a multivariate growth curve model that enables prediction of BDEs of unknown complexes. Mass spectral results were compared to computer-generated bond dissociation energies using Becke-style three-parameter density functional theory (B3LYP, employing the Lee-Yang-Parr correlation functional), with excellent agreement between experimental and theoretical energy values. The newly developed method is general in nature and can be used for the measurement of metal or halide ionic adduct bond dissociation energies and for the measurement of bond energies of noncovalent interactions such as dimer dissociation energies. The validity of the method has been rigorously established using a triple quadrupole, but it may also be applied to other mass spectrometers that allow user control of the collision cell potential.

Metallocene Allyl Reactivity in the Presence of Alkenes Tethered to Cyclopentadienyl Ligands

The reactions of the yttrium metallocene allyl complex [(C5Me4)SiMe2(CH2CHCH2)]2Y(C3H5), 1, with ethylene, trimethylaluminum, and hydrogen have been examined to determine how the olefins tethered to the cyclopentadienyl ligands interact with these species that are typically present in olefin polymerizations. Complex 1 was prepared from allylmagnesium chloride and [(C5Me4)SiMe2(CH2CHCH2)]2YCl, which can be directly prepared free of solvent and alkali metal halide adducts from YCl3(THF)x and [(C5Me4)SiMe2(CH2CHCH2)]K in THF. 1 was characterized by NMR spectroscopy and X-ray crystallography, and the data were compared to those of three related complexes: the pentamethyl analogue, (C5Me5)2Y(C3H5), 2, the ansa analogue, [Me2Si(C5Me4)2]Y(C3H5), 3, and the lutetium complex, (C5Me5)2Lu(C3H5), 4. Although 1 shows no evidence for insertion of the tethered olefins into the Y−(C3H5) bond, comparisons of the synthesis and variable-temperature NMR spectra of 1 with 2−4 suggest metal−alkene interaction. Complex 1 polymerizes ethylene and reacts with excess Al2Me6 to generate the allyl-free, tetramethylaluminate-bridged dimer {[(C5Me4)SiMe2(CH2CHCH2)]2Y[(μ-Me)2AlMe2]}2, 5. No involvement of the tethered olefins was observed in connection with this Y−C(allyl) bond breaking and Y−C(Me) bond making. The tethered olefins do become involved in the reaction chemistry of 1 in the presence of hydrogen: the tethered olefins of 1 are hydrogenated. A hydride derivative of 1 was not isolated, but 1 reacts with H2 in diethyl ether to form the expected hydride decomposition product, the ethoxide, {[(C5Me4)SiMe2(CH2CH2CH3)]2Y(OEt)}x, 6. Reaction of 1 with hydrogen in C6D6 and with deuterium in C6H6 shows that hydrogenation of the tethered olefin occurs before D/H exchange with arenes can occur in this system.

Negatively-Charged Halide Adducts of Homochiral Serine Octamers

Negatively charged halide adducts of serine octamers, (Ser(8)+2Cl)(2-) and (Ser(8)+2Br)(2-), appear as magic number clusters in the negative ion electrospray mass spectra of solutions containing serine and the halide. Like the well-known protonated serine octamer, these negatively charged adducts are formed with homochiral preference and also undergo chiroselective substitution reactions with other amino acids. Tandem mass spectra of negatively charged halide adducts of serine octamers show that these ions also have a characteristic fragmentation signature. The fact that octamers of both polarities display analogous chemical properties suggests that these may be characteristics of the so-far-unknown neutral octamer. If serine played a key role in the origin of homochirality on the primitive earth, it was likely through both the neutral octamer and the ionic adducts. Unlike the octamers, the formation of halide-containing serine cluster ions of particular sizes is unfavorable under the conditions of the experiment. Signals corresponding to the ions (Ser(9)+2Br)(2-) and (Ser(15)+2Br)(2-) are particularly low in intensity, giving rise to gaps in the distribution of serine/bromide clusters in the negative ion electrospray mass spectra. These cluster sizes are likely to correspond to unstable "anti-magic number" clusters recently reported by Clemmer.

Amido-bridged double-cube nitrido complexes containing titanium and magnesium/calcium

Treatment of the single cube nitrido complexes [(thf)x((Me3Si)2N)M((mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N))](M = Mg, x= 0; Ca, x= 1) with one equivalent of anilines NH2Ar in toluene affords the arylamido complexes [(ArHN)M((mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N))]n[M = Mg (3), n= 1, Ar = 4-MeC6H4; Ca (4), n= 2, Ar = 2,4,6-Me3C6H2]. The magnesium complex 3 has a single-cube structure whereas the X-ray crystal structure of the analogous calcium derivative 4 shows two cube-type azaheterometallocubane moieties Ca((mu3-N)(mu3-NH)2Ti3(eta5-C5Me5)3(mu3-N)) held together by two mu-2,4,6-trimethylanilido ligands. Complexes 3 and 4 react with chloroform-d1 at room temperature to give the metal halide adducts [Cl2M((mu3-NH)3Ti3(eta5-C5Me5)3(mu3-N))](M = Mg, Ca). A solution of 3 in n-hexane gave complex [(Mg2(mu3-N)(mu3-NH)5[Ti3(eta5-C5Me5)3(mu3-N)]2)(mu-NHAr)3] which shows three mu-4-methylanilido ligands bridging two [MgTi3N4] cube type cores according to an X-ray crystal structure determination.

Novel 1,3,2-diazabora-[3]ferrocenophanes and a 1,4,2,3-diazadibora-[4]ferrocenophane

N, N′-Dilithiated 1,1′-bis(trimethylsilylamino)ferrocene ( 2) reacts with boron halide adducts (HBBr 2–SMe 2; BF 3–OEt 2 and BBr 3–SMe 2), boron halides (BCl 3, BBr 3, BCl 2(OPh) and BCl 2(Ph)) and 1,1-bis(dimethylamino)dichlorodiborane(4) to give the corresponding 1,3-bis(trimethylsilyl)-1,3,2-diazabora-[3]ferrocenophanes ( 3)–( 8) and the 2,3-bis(dimethylamino)-1,4-bis(trimethylsilyl)-1,4,2,3-diazadibora-[4]ferrocenophane ( 9). All new complexes were characterised by multinuclear magnetic resonance spectroscopy in solution, and the solid-state molecular structures of the hydride ( 3), fluoride, chloride ( 4, 5), and of the phenoxy and phenyl derivatives ( 7, 8) were determined by X-ray analysis.

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXXVI Structural Studies in the Copper(I) Halide : Norbornadiene System

The structural characterizations of some copper(I) halide (CuX) adducts with norbornadiene (‘nbd’) are recorded. CuCl : nbd (1:1)4 (a redetermination), (2:1)2(∞|∞), are systems both based around Cu4Cl4 ‘cubane’-type cluster arrays. CuBr : nbd (7:3)(∞|∞)( 0.5 MeOH), a complex polymer with 3-symmetry, is believed to be the complex previously described as an adduct of 2:1 stoichiometry. Attempts to obtain an iodide counterpart have resulted in the definition of an ephemeral adduct CuI : MeCN (3:2)(∞|∞). 0.5 C7H8 in which, remarkably, the nbd is uncoordinated; the complex is a polymer, related to the [AgX(quinoline)](∞|∞) (X = Cl, Br) ‘saddle’ polymer.

Synthesis and luminescence studies of mono- and C3-symmetric, tris(ligand) complexes of Sm(iii), Y(iii) and Eu(iii) with sulfur-bridged binaphtholate ligands

A series of trivalent mono- and tris(ligand) lanthanide complexes of a sulfur-bridged binaphthol ligand [1,1'-S(2-HOC(10)H(4)Bu(t)(2)-3,6)(2)] H(2)L(SN), have been prepared and characterised both structurally and photophysically. The H(2)L(SN) ligand provides an increased steric bulk and offers an additional donor atom (sulfur) as compared with 1,1'-binaphthol (BINOL), a ligand commonly used to complex Lewis acidic lanthanide catalysts. Reaction of the diol H(2)L(SN) with [Sm[N(SiMe(3))(2)](3)] affords silylamido- and amino- derivatives [Sm(L(SN))[N(SiMe(3))(2)][HN(SiMe(3))(2)]] and the crystallographically characterised [Sm(L(SN))[N(SiMe(3))(2)](thf)(2)] with different degrees of structural rigidity, depending on the presence of coordinating solvents. The binaphthyl groups of the L(SN) ligand act as sensitisers of the metal centred emission, which is observed for the Eu(III) and Sm(III) complexes studied. We have therefore sought to use emission spectroscopy as a non-invasive technique to monitor a monomer-dimer equilibrium in these complexes. A dramatic difference between the emission properties of the unreactive dimeric Sm(III) aryloxide complex, the solvated monomeric analogues and the amido adduct demonstrated the potential use of such a technique. For a few representative lanthanides (Ln = Sm, Eu and Y) the reaction of the dilithium salt Li(2)L(SN) with either [Ln[N(SiMe(3))(2]3)] or [LnCl(3)(thf)(3)] affords only the homoleptic complex [Li(S)(3)][LnL(SN)(3)](S = thf or diethyl ether); we report the structural characterisation of the Sm complex. However, the reactions of this dipotassium salt K(2)L(SN) with [Sm[N(SiMe(3))(2)](3)] or [SmCl(3)(thf)(3)] give only [SmL(SN)N(SiMe(3))(2)], or intractable mixtures respectively, in which no (tris)binaphtholate is observed. The only isolable lanthanide-L(SN) halide adduct so far is [YbL(SN)I(thf)].

Anion binding to azamacrocycles: synthesis and X-ray crystal structures of halide adducts of [12]aneN4 and [18]aneN6

An investigation into the halide binding properties of two polyazamacrocycles [12]aneN4 (L1) and [18]aneN6 (L2) has resulted in the determination of the molecular structure of five compounds [H4L1(Br)4]·2H2O (1), [H2L1(I3)2]·2I2·2CH3CN (2), [H6L2(Cl)6]·4H2O (3), [H4L2(Br)4]·2H2O (4) and [H4L2(I)2(I3)2] (5). [18]aneN6 (L2) was generally found to bind two anions within the macrocyclic cavity. In the adducts formed by [12]aneN4 (1 and 2), the anions and solvent of crystallization do not sit within the [12]aneN4 cavity, instead preferring to occupy positions exterior to the macrocycle. Left- and right-handed helices are formed by the I3− and I2 moieties in 2 that house acetonitrile solvent molecules in the centre of the spiral. In most cases, chloride and bromide adopt trigonal pyramidal co-ordination motifs with various degrees of distortion from a regular geometry. The ring size, conformational flexibility and level of protonation were found to influence the halide binding characteristics of the macrocycles.

Synthesis, characterization and thermal degradation kinetics of cadmium halide adducts with imidazole

The synthesis, characterization and a nonisothermal thermal degradation kinetic study performed for the adducts CdCl2·Imi, CdCl2·2Imi, CdBr2·2Imi and CdBr2·3Imi (Imi = imidazole) are reported. For cadmium bromide the maximum number of imidazole molecules per cadmium cation to produce a stable (from a thermodynamic point of view) compound is three, at least for compounds prepared at room temperature and pressure. The kinetic study performed by the Coats–Redfern and Száko methods using thermogravimetric data shows that for all compounds the activation energy values associated with the release of imidazole molecules decreases as the thermal degradation process proceeds.

Polar Molecular Precursors for Alkali and Alkaline Earth Metal Clusters and Low‐Dimensional Polymer Structures: the Solid‐State Structures of [CaI(dme)3]I, and cis‐[SrI2(diglyme)2] (dme = CH3OC2H4OCH3; diglyme = CH3(OC2H4)2OCH3)

AbstractTwo new alkaline earth metal halide adducts with oxygen‐donor polyether ligands are described. One of them, cis[SrI2(diglyme)2], features two terminally bonded anions in vicinal positions, and at an angle of ca. 90°. The low bond valence sum of ca. 1.9 indicates how well the cation is shielded by its ligands in the solid state, and that ligand exchange can be expected in solution and upon reaction. The second compound, [CaI(dme)3]I, consists of an ion pair formed by the cationic complex [CaI(dme)3]+ with one anion in terminal position, and one iodide. Both compounds possess a strong dipole moment at the molecular level, but crystallize in centrosymmetric space groups. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Synthesis, characterization and TG–DSC study of cadmium halides adducts with caffeine

The synthesis, characterization and TG–DSC study of the compounds CdX 2· ncaff, for which X: Cl, Br and I; n=1 and 2 and caff: caffeine is reported. It is verified that caffeine is coordinated through more than one coordination site, despite the fact that the nitrogen of the imidazole ring is the main coordination site. The following thermal stability trend is observed: Cl>Br>I and monoadducts are more stable than bisadducts. The thermal degradation (td) enthalpies have the values (kJ mol −1): 58.2 and 71.5; 74.9 and 91.4; 31.1 and 47.5 for Cl, Br and I mono and bisadducts, respectively.

Isostructural or not? Adducts of some aryltin halides with (E)-1,2-bis(4-pyridyl)ethene.

The title complexes [mu-(E)-4,4'-(ethene-1,2-diyl)dipyridine-kappa(2)N:N']bis[halotris(4-methylphenyl)tin(IV)], [Sn(2)(C(7)H(7))(6)X(2)(C(12)H(10)N(2))], where halo is chloro (X = Cl) and bromo (X = Br) are isostructural. In both crystals, the molecules lie on inversion centers, and there are voids of ca 80 A(3) that could, but apparently do not, accommodate water molecules. The corresponding iodo structure (X = I) is almost, but not quite, isostructural with the other two compounds; when Br is changed to I, the length of the c axis decreases by more than 1 A and the voids are no longer large enough to accomodate any solvent molecule. The related complex [mu-(E)-4,4'-(ethene-1,2-diyl)dipyridine-kappa(2)N:N']bis[chlorotriphenyltin(IV)], [Sn(2)(C(6)H(5))(6)Cl(2)(C(12)H(10)N(2))], crystallizes in a related structure, but the molecules lie on general rather than on special positions. The molecular structures of the four complexes are similar, but the conformation of the phenyl derivative is approximately eclipsed rather than staggered.

Synthesis, characterization and thermogravimetric study of zinc group halides adducts with imidazole

The synthesis, characterization and thermogravimetric study of the adducts ZnCl 2·2Imi, ZnBr 2·2Imi, CdCl 2·Imi, CdCl 2·2Imi, CdBr 2·2Imi, CdBr 2·3Imi, CdI 2·2.5Imi, HgCl 2·2Imi, HgBr 2·1.5Imi and HgI 2·1.5Imi (Imi = imidazole) is reported. The following sequence of thermal stability is observed for the synthesized adducts: Zn>Hg>Cd. It is also verified that larger cations, as well as larger anions, result in a smaller number of imidazole molecules in the coordination sphere of the considered cation and that hard acids exhibit stronger bonds to imidazole than soft acids, and this fact is reflected in the thermal stability sequence. ZnCl 2·2Imi behaves as a non-electrolyte in acetonitrile and ethanol, whereas ZnBr 2·2Imi is a non-electrolyte in acetonitrile and a 1:1 electrolyte in ethanol. CdI 2·2.5Imi is a non-electrolyte in acetonitrile and a 1:2 electrolyte in ethanol.

Unusual structural variations within a family of thioether macrocyclic complexes. Tin(iv) halide adducts of [12]-, [14]- and [16]-aneS4

The hydrolytically sensitive compounds [(SnCl4)2([n]aneS4)] (n = 12, 14, 16) and [SnBr4([n]aneS4)] are obtained in good yield upon reaction of 2 mol. equiv. of the parent tin tetrahalide with 1 mol. equiv. of macrocycle in rigorously anhydrous CH2Cl2 solution. Reactions of [16]aneSe4 with SnX4 (X = Cl or Br) affords [SnX4([16]aneSe4)], while reaction of [8]aneSe2 gives [SnCl4([8]aneSe2)]. The crystal structures of the three closely related complexes [SnBr4([12]aneS4)], [SnBr4([14]aneS4)]·2/3CH2Cl2 and [SnBr4([16]aneS4)] have been determined. These species represent the first examples of Sn(IV) halide adducts with neutral Group 16 ligands which adopt polymeric structures. The complexes are all chain polymers, although there is unexpected structural dependence upon the macrocycle ring-size, giving each a distinct structural form. Unusually, the coordinated S atoms in both [SnBr4([14]aneS4)]·2/3CH2Cl2 and [SnBr4([16]aneS4)] adopt a mutually trans arrangement. Far-IR spectra indicate that the chloro complexes all exist as cis octahedral tin(IV) species. Solution NMR spectroscopy shows that the tetrathia and tetraselena macrocyclic complexes are extensively dissociated at 295 K.

Quantum-Chemical Study of Silicon Halide Adducts with Nitrogen-containing Donors: III. Energy Effects of Ammonolysis and Complex-Formation Reactions in Silicon Tetrahalide-Ammonia Systems

Thermodynamic characteristics of hydrogen halide elimination from SiX4-NH3 systems were calculated by the B3LYP density functional method. The role of adducts and oligomeric forms of compounds containing Si-N bonds, as intermediates in the chemical vapor deposition of silicon nitride, was considered. It was shown experimentally that the reaction between silicon tetrachloride and ammonia in nonaqueous solvents involves ammonolysis.

Carbon dioxide/epoxide coupling reactions utilizing Lewis base adducts of zinc halides as catalysts. Cyclic carbonate versus polycarbonate production.

The reactions of zinc halides with 2,6-di-methoxypyridine or 3-trifluoromethylpyridine in dichloromethane have led to the formation of quite different complexes. Specifically, reactions involving pyridine containing electron donating methoxy substitutents have provided salts of the type [Zn(2,6-dimethoxypyridine)4][Zn2X6], as revealed by elemental analysis and X-ray crystallography. On the other hand, simple bis-pyridine adducts of zinc halides were isolated from the reactions involving the pyridine ligand with electron withdrawing substituents and characterized by X-ray crystallography, for example, Zn(3-trifluoromethylpyridine)2Br2. These zinc complexes were shown to be catalytically active for the coupling of carbon dioxide and epoxides to provide high molecular weight polycarbonates and cyclic carbonates, with the order of reactivity being Cl > or = Br > I, and 2,6-di-methoxypyridine > 3-trifluoromethylpyridine. Polycarbonate production from carbon dioxide and cyclohexene oxide was shown to be first-order in both metal precursor complex and cyclohexene oxide, as monitored by in situ infrared spectroscopy at 80 degrees C and 55 bar pressure. For reactions carried out in CO2 swollen epoxide solutions in the absence of added quantities of pyridine, the copolymer produced contained significant polyether linkages. Alternatively, reactions performed in the presence of excess pyridine or in hydrocarbon solvent, although slower in rate, afforded completely alternating copolymers. For comparative purposes, zinc chloride was a very effective homopolymerization catalyst for polyethers. Additionally, zinc chloride afforded copolymers with 60% carbonate linkages in the presence of high carbon dioxide pressures. In the case of cyclohexene oxide, the copolymer back-biting reaction led exclusively to the production of the trans cyclic carbonate as shown by infrared spectroscopy in v(C=O) region and X-ray crystallography. The unique feature of these catalyst systems is their simplicity.

(CuI)3P4S4: Preparation, Structural, and NMR Spectroscopic Characterization of a Copper(I) Halide Adduct with β‐P4S4.

AbstractFor Abstract see ChemInform Abstract in Full Text.