Moisture-sensitive Compound Research Articles

Bis(η5-cyclo-penta-dien-yl)(2-{[(2-meth-oxy-phen-yl)imino]-meth-yl}phenolato-κ3 O,N,O')terbium.

The air- and moisture-sensitive title compound, [Tb(C5H5)2(C14H12NO2)], was synthesized from tris-(cyclo-penta-dien-yl)(tetra-hydro-furan)-terbium and 2-{[(2-meth-oxy-phen-yl)imino]-meth-yl}phenol. Each Tb atom is coordinated by two cyclo-penta-dienyl ligands in an η5-coordination mode and by one N and two O atoms of the organic ligand in a tridentate κ3 O,N,O'-mode.

Compliant Yet Brittle Mechanical Behavior of Li2s-P2S5 Li-Ion Conducting Solid Electrolyte

Li-ion batteries that include all solid-state components show promise as an emerging energy storage technology, as the solid electrolyte can improve safety and enable longer cycle life than current batteries based on flammable and reactive liquid electrolytes. Mechanical compatibility and durability of the solid components during large intercalation-induced volume changes are key concerns. For example, deformation and fracture of the solid electrolyte during cycling is expected to slow Li-ion conduction and create pathways for dendritic growth of metallic Li that can short-circuit the device. Identification and evaluation of key mechanical parameters of solid electrolytes is critical to predicting designs mitigating mechanical degradation. With Li conductivity in excess of 10-4 S/cm, 70/30 mol% Li2S-P2S5 (LPS) is among the most promising solid electrolytes to date. Here we fabricated LPS and verified its amorphous structure and high ionic conductivity by X-ray diffraction and electrochemical impedance spectroscopy, respectively. We evaluated mechanical properties including Young’s elastic modulus, hardness, and fracture toughness via instrumented indentation as 18.5 +/- 0.9 GPa, 1.9 +/- 0.2 GPa, and 0.23 +/- 0.04 MPa m1/2, respectively. These measurements were enabled by immersion of the sample in nonreactive fluids that stabilized composition of this moisture-sensitive compound. We found Young’s modulus to be in agreement with prior published values derived with alternative measurement techniques, and report the first measurements of hardness and fracture toughness. While the stiffness and hardness of this solid electrolyte material were much lower than that of active materials within battery electrodes, the fracture toughness was also surprisingly low relative to typical glass and ceramic materials. Thus, the mechanical behavior of this candidate solid electrolyte is compliant (low resistance to reversible deformation) and brittle (low resistance to fracture). We will discuss the relationship between these observed mechanical properties and integration of these materials as solid electrolytes in all-solid-state batteries.

A Redox-Switchable Germylene and its Ligating Properties in Selected Transition Metal Complexes.

The synthesis, structure, and full characterization of a redox-switchable germylene based on a [3]ferrocenophane ligand arrangement, [Fc(NMes)2 Ge] (4), is presented. The mesityl (Mes)-substituted title compound is readily available from Fc(NHMes)2 (2) and Ge{N(SiMe3 )2 }2 , or from the dilithiated, highly air- and moisture-sensitive compound Fc(NLiMes)2 ⋅3 Et2 O (3) and GeCl2 . Cyclic voltammetry studies are provided for 4, confirming the above-mentioned view of a redox-switchable germylene metalloligand. Although several 1:1 RhI and IrI complexes of 4 (5-7) are cleanly formed in solution, all attempts to isolate them in pure form failed due to stability problems. However, crystalline solids of [Mo(κ1 Ge-4)2 (CO)4 ] (8) and [W(κ1 Ge-4)2 (CO)4 ] (9) were isolated and fully characterized by common spectroscopic techniques (8 by X-ray diffraction). DFT calculations were performed on a series of model compounds to elucidate a conceivable interplay between the metal atoms in neutral and cationic bimetallic complexes of the type [Rh(κ1 E-qE)(CO)2 Cl]0/+ (qE=[Fc(NPh)2 E] with E=C, Si, Ge). The bonding characteristics of the coordinated Fc-based metalloligands (qE/qE+ ) are strongly affected upon in silico oxidation of the calculated complexes. The calculated Tolman electronic parameter (TEP) significantly increases by approximately 20 cm-1 (E=C) to 25 cm-1 (E=Si, Ge) upon oxidation. The change in the ligand-donating abilities upon oxidation can mainly be attributed to Coulombic effects, whereas an orbital-based interaction appears to have only a minor influence.

How to stabilize cilazapril-containing solid dosage forms? The optimization of a final drug formulation

Cilazapril, a moisture-sensitive compound, is known to undergo rapid degradation which could be additionally facilitated by the presence of excipients that contain or absorb moisture. Hence we investigated the stability of cilazapril in two commercially-available dosage forms and in binary mixtures with the selected excipients used in the studied commercial formulations i.e.: hypromellose, lactose monohydrate, maize starch and talc in order to detect any possible, stability-affecting incompatibilities. Also the impact of the blister made of oriented polyamide/aluminum/polyvinyl chloride//aluminum on cilazapril-containing tablets was researched. A validated HPLC and HPLC-MS methods were used for analysis and the isothermal stress testing conditions were applied (temperature range 318–343K, relative humidity 76.4% for tablets and temperature 333K, relative humidity range 50.9–76.4% for binary mixtures). It was shown that the degradation of cilazapril in both, model mixtures and tablets follows the autocatalytic model kinetics and it is more rapid than that observed for pure substance, evidenced by higher degradation rate constants. The immediate packaging protects cilazapril in tablets from degradation only in case of the original drug while in its blistered generic counterpart a slight but statistically insignificant increase of cilazapril decay occurs when compared to bare tablets (p<0.05). The degradation product of cilazapril in tablets and binary mixtures was identified as cilazaprilat. It was also observed that the increase of relative humidity or the presence of hypromellose, lactose and talc significantly impairs the stability of cilazapril in the aforementioned order. Only maize starch exhibited a positive effect on cilazapril stability (10.8% loss of cilazapril in binary mixture after 360days of stressing compared to 35% loss of pure cilazapril in analogous test conditions) probably thanks to its moisture-scavenging properties. It was suggested that in the manufacture of cilazapril-containing solid dosage forms the procedure of wet granulation should be avoided while hygroscopic excipients should be substituted by their non-hygroscopic counterparts.

Synthesis and deprotonation of (phenylselenolatodimethylsilyl)bis(trimethylsilyl) methane: The crystal structure of (Me3Si)2(Me2SiBr)CH

The moisture-sensitive compound [{bromodimethylsilyl}bis(trimethylsilyl)methane], [(Me3Si)2(Me2SiBr)CH] 1 has been synthesized by the bromination of the hydride [(Me3Si)2(Me2SiH)CH] in CCl4 in good yield. Compound 1 has been characterized by multinuclear NMR and a single crystal X-ray diffraction studies. The average Si–C and BrMe2Si–C distances are, respectively, 1.894(2) and 1.886(2) Å. The Si–C–Si angle is 114.98(13)°. Treatment of 1 with NaSePh (obtained from the sodium triethylborohydride reduction of diphenyldiselenide) in benzene at room temperature resulted in the isolation of light yellow oil, [{phenylselenatodimethylsilyl}bis(trimethylsilyl)methane], [(Me3Si)2(Me2SiSePh)CH] 2. Compound 2 has been metallated with methyllithium as well as lithium diisopropylamide (LDA) in THF to give [(Me3Si)2(Me2SiSePh)CLi·2THF] 3. Compounds 2 and 3 have been characterized by elemental analysis, mass and multinuclear NMR studies.

β‐Diketiminate Stabilized Magnesium Hydroxide, Heterobimetallic, and Halide Complexes: Synthesis and X‐ray Structural Studies

AbstractThe controlled hydrolysis of heteroleptic magnesium amide, LMgN(SiMe3)2 (L = CH[C(Me)N(2,6‐iPr2C6H3)]2) with water afforded the corresponding hydroxide [LMg(OH)·THF]2 as air and moisture sensitive compound. The presence of a sterically bulky β‐diketiminate ligand prevents the self‐condensation reaction of this hydroxide complex. Single crystal X‐ray analysis shows that the hydroxide is dimeric in the solid state. Reaction of the magnesium amide or LMg(Me)·OEt2 with LAlMe(OH) generates the heterobimetallic species containing the Mg–O–Al moiety. Additionally, the reaction of methylmagnesiumchloride with the free ligand leads to complex L′MgCl (L′ = CH[Et2NCH2CH2N(CMe)]2). As revealed by the crystal structure, L′MgCl is a solvent free monomeric magnesium chloride complex that is analogues to the Grignard reagent.

Synthesis and Crystal Structure of Barium Indide Ba9In4

A new binary compound in the system Ba-In has been synthesized and structurally characterized. According to singlecrystal X-ray diffraction data Ba9In4 crystallizes with tetragonal symmetry (I4/m, a = 13.948(2), c = 5.888(1) Å, V = 1145.5(3) Å3, Z = 2, R1 = 0.037, wR2 = 0.071). The very moisture-sensitive compound could be obtained as single phase by reaction of metallic barium and indium at 350 °C.

Structures of incommensurate and commensurate composite crystals RbxMnO2(x= 1.3711, 1.3636)

Rb(1.3711)MnO(2) (Rb(11)Mn(8)O(16)) has been synthesized via the azide/nitrate route from a stoichiometric mixture of the precursors Mn(2)O(3), RbNO(3) and RbN(3). The structure of this extremely air- and moisture-sensitive compound can best be described in terms of an incommensurate composite structure, built up by a honeycomb-like framework of Rb ions, as one subsystem and by a second subsystem of chains, consisting of edge-sharing MnO(4/2) tetrahedra. These two composite substructures interpenetrate in such a way that the manganate chain polyanions centre the channels of the Rb-honeycomb framework. Crystals transform by an aging process into Rb(1.3636)MnO(2) (Rb(15)Mn(11)O(22)), which has a similar structure but a different commensurate modulation. Two reasons can be established for the origin of the modulations: the charge ordering of Mn(2+)/Mn(3+) on one hand, and the incompatibility of the Mn-Mn and Rb-Rb separations on the other.

A Three-Coordinate and Quadruply Bonded Mo−Mo Complex

Reaction of MoCl3(THF)3 with [Me2Si{NLi(Dipp)}2]2 (Dipp = 2,6-i-PrC6H3) afforded a triply bonded dimolybdenum complex 1,2-Mo2Cl2[Me2Si(NDipp)2]2 1, spanned by two Me2Si[N(Dipp)]2 ligands, thus resulting in a syn conformation. The air- and moisture-sensitive compound 1 was characterized by NMR spectroscopic, elemental, and single-crystal X-ray crystallographic analysis. Reduction of 1 by Na/Hg yielded the quadruply bonded dimeric complex Mo2[Me2Si(NDipp)2]2 2, which was also characterized by the aforementioned analytical methods. The Mo-Mo bond was determined to be 2.1784(12) A, which is considered a long quadruple bond. In addition, density functional theory (DFT) computations on compound 2 provided insight into the intriguing Mo-Mo quadruple bond.

On the Chemistry of Zn−Zn Bonds, RZn−ZnR (R = [{(2,6-Pri2C6H3)N(Me)C}2CH]): Synthesis, Structure, and Computations

Potassium reduction of RZn(mu-I)2Li(OEt2)2 (R = [{(2,6-Pri2C6H3)N(Me)C}2CH]) affords the second compound with a Zn-Zn bond, RZn-ZnR. The air- and moisture-sensitive title compound was characterized by 1H NMR, elemental analyses, and single-crystal X-ray diffraction. The Zn-Zn bond was determined to be 2.3586(7) A; this value is only about 0.05 A longer than the Zn-Zn bond reported for Cp*Zn-ZnCp* (Cp* = C5Me5), the first reported compound with a Zn-Zn bond. In addition, density functional theory (DFT) computations on related model RZn-ZnR compounds provide insight into the intriguing Zn-Zn bond.

The effects of packaging on the stability of a moisture sensitive compound

Packages that provided stability (less than a 10% loss in potency) of a moisture sensitive compound (PGE-7762928) in tablet form at accelerated conditions for 6 months were identified. The equilibrium moisture content of the tablets at 25°C/60%RH, 30°C/60%RH and 40°C/75%RH were 2.3, 2.4, and 2.9%, respectively. The tablet equilibrium moisture content, degradation rate of unpackaged product, and the moisture barrier properties of the packages were used to predict the stability of the packaged product. The physical and chemical stability (HPLC assay) of the products were measured after 2, 4, 6, 8, 12, and 24 weeks at ICH conditions. The Containers-Permeation 1 of polyvinyl chloride blisters, cyclic olefin blisters, aclar blisters, cold-form aluminum blisters was 0.259, 0.040, 0.008 and 0.001 mg per blister per day, respectively. At 6 months at 40°C/75%RH, the percent active was 84% in polyvinyl chloride blisters, 91% in cyclic olefin blisters, 97% in aclar blisters, 100% in cold-form aluminum blisters and 99% in an high density polyethylene bottle with a foil induction seal. The stability results for the packaged product were fairly consistent with the predictions based on the moisture sensitivity of the product and the moisture barrier properties of the respective package. To gain a better prediction, the flux value determined by the Containers-Permeation procedure was adjusted for the internal moisture concentration of the blister.

Reaction of organolead triacetates with 4-ethoxycarbonyl-2-methyloxazol-5-one. The synthesis of α-aryl and α-vinyl N-acetylglycine ethyl esters and their enzymic resolution

An efficient synthesis of the moisture-sensitive compound, 4-ethoxycarbonyl-2-methyloxazol-5-one, has been achieved. This compound undergoes high-yielding arylation and vinylation at the 4-position with organolead triacetates to give compounds which in water are converted to α-aryl and α-vinyl N-acetylglycine ethyl esters. These α-substituted glycine derivatives may be kinetically resolved in very good yield and high enantiomeric excess by enzymic hydrolysis of either the ester group or the amide function of the corresponding carboxylic acids.

One-dimensional coordination polymers: [{(pyridine)2Eu(.mu.-SeC6H5)2}4].infin. and [(THF)3Eu(.mu.-SeC6H5)2].infin.

Simple organochalcogenolate ligands tend to span metal centers, and this tendency can be used to prepare polymeric materials that resemble solid-state compounds in limited dimensionality. In this communication, we describe the synthesis and structural characterization of two one-dimensional coordination polymers of bis(phenylselenolato)-europium(II): [(THF)[sub 3]Eu([mu]-SeC[sub 6]H[sub 5])[sub 2]][sub [infinity]] and [(pyridine)[sub 2]Eu-([mu]-SeC[sub 6]H[sub 5])[sub 2][sub 4]][sub [infinity]]. Both of these air and moisture sensitive compound reflect the tendency of chalcogenolate ligands to bridge metal centers and the tendency of the rare earth elements to optimize electrostatic interactions. 8 refs., 2 figs.

A tricarbonyl, tetranuclear tungsten cluster supported by alkoxide ligands: W 4(OCH 2Pr i) 12(η 2,μ 4-CO)(CO) 2

Hydrocarbon solutions of W 4(OCH 2Pr i) 12 react with carbon monoxide (3–6 equiv.) to give a green, air and moisture sensitive compound W 4(CO) 3(OCH 2Pr i) 12, which has been characterized by infrared and NMR spectroscopy in solution and by a single crystal X-ray analysis in the solid state. The latter revealed a “spiked triangle” of tungsten atoms with WW bonding distances ranging from 2.658(2) Å to 2.806(3) Å, all supported by bridging alkoxides. Two carbonyl ligands are cis to one another on a tungsten atom contained in the basal W 3 triangle. The η 2,μ 4-CO ligand is C bonded to each of the three tungsten atoms in the basal triangle and O bonded to the “spiked” W atom. The η 2,μ 4-CO ligand contains a highly reduced carbon monoxide moiety that may be viewed as a μ 3-oxyalkylidyne ligand and provides a model for partial reduction of CO on a metal surface in the steps preceding reductive cleavage to carbide and oxide. The solution NMR data are consistent with expectations based on the solid-state structure. Crystal data for W 4(CO) 3(OCH 2Pr i) 12 at −141°C: a 13.361(5) Å, b 22.703(11) Å, c 11.627(5) Å, α 94.46(3)°, β 107.30(2)°, γ 102.79(3)°, Z = 2, d calcd 1.737 g cm −3, space group P 1 .

ChemInform Abstract: Reactions of Transition Metal Halides with Derivatives of Dimethylsulfoximine. X‐Ray Single Crystal Structure Analysis of F5WNS(O)Me2 and F4W(NS(O)Me2)2.

AbstractThe sulfoximine (I) reacts with WF6(II) to yield the air‐ and moisture‐sensitive compound (III), which reacts further with (I) to give the cis‐derivative (IV).

ChemInform Abstract: 4‐Methyl‐1,2,3,5‐dithiadiazolium Salts. Crystal Structures of (CH3CN2S2)5(CoCI4)Cl3 and (CH3CN2S2)Cl

AbstractThe reaction of trithiazyl Chloride (I) with CoCl2 in acetonitrile yields the moisture sensitive compound (III).

Dimeric 1,4‐Dichloro‐2,3,5,6‐tetramethyl‐1,4‐dialumina‐2,5‐cyclohexadiene, a Compound with Aluminum‐Olefin π‐Bonds

The low-temperature reaction of the “high-temperature” molecule AICI—the first preparative application of an Al subhalide—with CH3CCCH3 gives the title compound 1. The monomers of this air- and moisture-sensitive compound are twisted by 90° with respect to each other. The dimer is held together by four Al-olefin π bonds. Such compounds were previously unknown.

S4N4 as Tridentate Ligand in [IrX(CO)(PPh3)(S4N4)] Complexes

An iridium-sulfur-nitrogen heterobicycle having a [4.3.0] framework is present in the air- and moisture-sensitive title compound 1. This surprising result was obtained by structure analysis of the long-known compound. The tridentate coordination of S4N4 to a transition-metal haldie is new; usually, the coordination occurs through a lone pair of electrons on a nitrogen atom. The bulky triphenylphosphane group is omitted in the picture on the right.

Synthesis of the new ring system, Pyrazolo[3,4‐d][1,3]diazepine. A novel route for the synthesis of azolo[1,3]diazepines

AbstractA reduction of the nitrile group of 5‐amino‐4‐cyano‐1‐methylpyrazole (3) has provided the very versatile compound 5‐amino‐1‐methylpyrazole‐4‐carboxaldehyde (4). The amino group of 4 was protected using di‐methylformamide dimethylacetal and the aldehyde group was then reacted with trimethylsilyl cyanide to afford the moisture sensitive compound 5‐[[(dimethylamino)methylene]amino]‐4‐[cyano(trimethylsiloxy)‐methyl]‐1‐methylpyrazole (10). The cyano group of the cyanohydrin 10 was reduced using a cobalt boride catalyst to afford an intermediate aminomethyl group which was involved in an in situ annulation. This reaction provided 1‐methyl‐1,4,5,6‐tetrahydropyrazolo[3,4‐d][1,3]diazepin‐4‐ol, a derivative of the new ring system, pyrazolo[3,4‐d][1,3]diazepine.

Zur Chemie des Bis(methylsulfonyl)-amins (Dimesylamins), V [1] N-Chlorsulfonyl-methansulfonamid: Ein Produkt der Reaktion von Tetramethylsilan mit Imido-bis(schwefelsäurechlorid) / Investigations on Bis(methylsulphonyl)-amine (Dimesylamine), V [1] N-Chlorosulphonyl-methanesulphonamide: A Reaction Product from Tetramethylsilane and Imido-bis(sulphuryl chloride)

Abstract Tetramethylsilane reacts with HN(SO2Cl)2 (1) in a complex manner, the nature of the product mixture depending strongly on the reaction conditions. Refluxing 1 with TMS in excess, using CH2Cl2 as a diluent, affords in high yield the new compound HN(SO2Cl)(SO2Me) (2) according to eq. (3). Hydrolysis of the crystal-line, moisture sensitive compound 2 is described by eq. (4).