Nitrogen-Rich 5-(1-Methylhydrazinyl)tetrazole and its Copper and Silver Complexes

Nitrogen-rich 5-(1-methylhydrazinyl)­tetrazole (<b>1</b>, MHT) was synthesized by using a straightforward method. White plate crystals of <b>1</b> were isolated in acetonitrile and crystallized in the monoclinic system <i>P</i>2₁/<i>c</i> (# 14) (<i>a</i> = 3.8713(18) Å, <i>b</i> = 12.770(6) Å, <i>c</i> = 9.974(5) Å, α = 90°, β = 93.397(6)°, γ = 90°, <i>V</i> = 492.3(4) ų, <i>Z</i> = 4). The reactions of Cu­(II) and Ag­(I) ions in aqueous solution with <b>1</b> were investigated and found to form two complexes under mild conditions. The crystal structures of <b>2</b> and <b>3</b> are discussed with respect to the coordination mode of the MHT anion. Thermal stabilities were determined from differential scanning calorimetry (DSC) combined with thermogravimetric analysis (TGA) tests. Impact sensitivity was determined by BAM standards showing that these MHT salts are insensitive to impact (>40 J) confirmed by UN standards. The energies of combustion of <b>1</b>–<b>3</b> were determined using oxygen bomb calorimetry values and were used to obtain the corresponding enthalpies of formation. Combined with these data above, the neutral MHT is an attractive nitrogen-rich ligand for metallic energetic materials. Its copper and silver coordinated complexes are of interest as potential “green” metal energetic materials with high thermal stability as well as low sensitivity to impact and a high molar enthalpy of formation

Nitrogen-Rich 5-(1-Methylhydrazinyl)tetrazole and its Copper and Silver Complexes

Nitrogen-rich 5-(1-methylhydrazinyl)­tetrazole (<b>1</b>, MHT) was synthesized by using a straightforward method. White plate crystals of <b>1</b> were isolated in acetonitrile and crystallized in the monoclinic system <i>P</i>2₁/<i>c</i> (# 14) (<i>a</i> = 3.8713(18) Å, <i>b</i> = 12.770(6) Å, <i>c</i> = 9.974(5) Å, α = 90°, β = 93.397(6)°, γ = 90°, <i>V</i> = 492.3(4) ų, <i>Z</i> = 4). The reactions of Cu­(II) and Ag­(I) ions in aqueous solution with <b>1</b> were investigated and found to form two complexes under mild conditions. The crystal structures of <b>2</b> and <b>3</b> are discussed with respect to the coordination mode of the MHT anion. Thermal stabilities were determined from differential scanning calorimetry (DSC) combined with thermogravimetric analysis (TGA) tests. Impact sensitivity was determined by BAM standards showing that these MHT salts are insensitive to impact (>40 J) confirmed by UN standards. The energies of combustion of <b>1</b>–<b>3</b> were determined using oxygen bomb calorimetry values and were used to obtain the corresponding enthalpies of formation. Combined with these data above, the neutral MHT is an attractive nitrogen-rich ligand for metallic energetic materials. Its copper and silver coordinated complexes are of interest as potential “green” metal energetic materials with high thermal stability as well as low sensitivity to impact and a high molar enthalpy of formation

Theoretical Enthalpies of Formation of [AA]X and [AAE]X Type Amino Acid Ionic Liquids

The theoretical enthalpies of formation of 108 [AA]­X and [AAE]­X type amino acid ionic liquids composed of 12 amino acid cations (Gly⁺, GlyC₁⁺, Ala⁺, AlaC₁⁺, Pro⁺, ProC₁⁺, Phe⁺, PheC₁⁺, Val⁺, ValC₁⁺, Leu⁺, LeuC₁⁺) with 9 different anions (Cl^–, BF₄^–, PF₆^–, N­(CF₃SO₂)₂^–, CH₃CO₂^–, CF₃CO₂^–, CF₃SO₃^–, HSO₄^–, SO₄^2–) were studied. A systematic theoretical study on these amino acid ionic liquids was performed by quantum chemistry calculation using the Gaussian03 program. The geometric optimization and the frequency analyses were carried out using the B3LYP method with the 6-31+G** basis set. Their calculated enthalpies of formation were derived from the single point energies carried out with the MP2/6-311++G** level of theory. The enthalpies of formation of these amino acid ionic liquids were calculated to be from −2577.0 kJ·mol^–1 to −311.3 kJ·mol^–1. The negative values show their stable thermodynamics status. The energy differences between the predicted enthalpies of formation of each amino acid salt and those of their two neutral precursors were studied. The experimental enthalpies of formation of five amino acid ionic liquids [Gly]­Cl, [Ala]­Cl, [Ala]­HSO₄, [Pro]­CF₃CO₂, and [Pro]­CF₃SO₃ were obtained from the corresponding energies of combustion determined by the bomb calorimetry method. The experimental enthalpies of formation are in good agreement with corresponding theoretical results. This study provides an effective theoretical method to predict the thermodynamic stability of the preparation of new amino acid ionic liquids

Diffusion coefficients (<i>D</i>_o), transfer coefficients (<i>α</i>) and energy of activation (<i>E</i>_a) of Eu(III), Sm(III), Dy(III) and Nd(III) in BmimBr at different temperatures.

<p>Diffusion coefficients (<i>D</i>_o), transfer coefficients (<i>α</i>) and energy of activation (<i>E</i>_a) of Eu(III), Sm(III), Dy(III) and Nd(III) in BmimBr at different temperatures.</p

Cyclic voltammograms of Eu(III) measured in BmimBr with different scan rates.

<p>Cyclic voltammograms of Eu(III) measured in BmimBr with different scan rates.</p

Plots of cathodic peak current intensity (<i>i</i>_p) against square-root of the potential scan rate (<i>ν</i>^1/2); ▪, Eu(III); •, Sm(III); ▴, Dy(III); ▾, Nd(III).

<p>Plots of cathodic peak current intensity (<i>i</i>_p) against square-root of the potential scan rate (<i>ν</i>^1/2); ▪, Eu(III); •, Sm(III); ▴, Dy(III); ▾, Nd(III).</p

Peak potentials <i>E</i>_p^c, <i>E</i>_p/2^c and |<i>E</i>_p^c−<i>E</i>_p/2^c| of Eu(III), Sm(III), Dy(III) and Nd(III) in BmimBr at different temperatures.

<p>Peak potentials <i>E</i>_p^c, <i>E</i>_p/2^c and |<i>E</i>_p^c−<i>E</i>_p/2^c| of Eu(III), Sm(III), Dy(III) and Nd(III) in BmimBr at different temperatures.</p

Cyclic voltammograms of Eu(III) (A), Sm(III) (B), Dy(III) (C) and Nd(III) (D) measured in BmimBr at different temperatures.

<p>Cyclic voltammograms of Eu(III) (A), Sm(III) (B), Dy(III) (C) and Nd(III) (D) measured in BmimBr at different temperatures.</p

Plots of <i>E</i>⁰*_{Eu(III)/Eu(II)} against <i>T</i>.

<p>Plots of <i>E</i>⁰*_{Eu(III)/Eu(II)} against <i>T</i>.</p

Plots of ln<i>D</i>_o against <i>T</i>⁻¹, ▪, Eu(III); •, Sm(III); ▴, Dy(III); ▾, Nd(III) measured in BmimBr at GC electrode.

<p>Plots of ln<i>D</i>_o against <i>T</i>⁻¹, ▪, Eu(III); •, Sm(III); ▴, Dy(III); ▾, Nd(III) measured in BmimBr at GC electrode.</p