Synthesis of Diazeniumdiolates from the Reactions of Nitric Oxide with Enolates

Reactions of nitric oxide with enolates derived from aliphatic methyl ketones containing α-methylene or α-methine groups and with enolates derived from α,α‘-dimethylene or α,α‘-dimethine ketones yield mono- or bis(diazeniumdiolate) products. Diazeniumdiolation occurs in the following order:  α-methine > α-methylene > α-methyl. The amount of the base used alters the extent of diazeniumdiolation and the course of the reaction. Mono- and bis(diazeniumdiolate)-substituted methyl ketones are cleaved in the presence of excess base before and after the subsequent diazeniumdiolation of the α-methyl group. Similar to the trihalogenated methyl groups in the base-assisted halogenation reactions of methyl ketones, the bis(diazeniumdiolate)-substituted α-methylene and α-methyl groups act as leaving groups in the presence of excess base. The reaction of nitric oxide with a (∼20:80, cis/trans) mixture of 2,6-cyclohexananone yields the cis and trans isomers of 2,6-dimethylcyclohexanone-2,6-bis(diazeniumdiolate) in 12.9% and 57.6% yield. Single-crystal X-ray diffraction data determined for potassium cis-2,6-dimethylcyclohexanone-2,6-bis(diazeniumdiolate), cis-14b, reveal that the N2O2- substituent is planar with considerable delocalization of a double bond over the anionic four-atom group. Except for one of the diazeniumdiolate products, namely, potassium propanoate 2,2-bis(diazeniumdiolate), 8b, all are stable in neutral and basic aqueous media. Compound 8b slowly decomposes in neutral aqueous solution releasing nitrous oxide and nitric oxide gases but is stable in basic aqueous media. Differential scanning calorimetry data measured for the diazeniumdiolate products indicate that they decompose exothermally with most of them undergoing explosive decomposition at moderately high temperatures (181−274 °C)

Nucleophilic Addition of Hydroxylamine, Methoxylamine, and Hydrazine to Malononitrileoxime

The chemistry of malononitrileoxime, HONC(CN)2, with respect to nucleophilic addition to ammonia, methylamine, hydroxylamine, methoxylamine, and hydrazine is reported. Whereas the poorly nucleophilic ammonia and methylamine do not react, hydroxylamine, methoxylamine, and hydrazine add to the nitrile groups of the oxime, yielding the corresponding amidoximes and amidrazones. Depending on the stoichiometry of the reactions, hydroxylamine and hydrazine add to one or both of the nitrile groups; methoxylamine adds to only one of the nitrile groups. Three of the products, namely, cyanoacetamidoxime (1), 3-amino-2,3-hydroxyiminopropionitrile monohydrate (2·H2O), and 3,5-diaminopyrazolone-4-oxime monohydrochloride monohydrate (6·HCl·H2O), are characterized by single-crystal X-ray diffraction data. All of the products exhibit exothermic decomposition properties with heats of decomposition in the range of 500−1500 kJ mol-1

Synthesis of Diazeniumdiolates from the Reactions of Nitric Oxide with Enolates

Reactions of nitric oxide with enolates derived from aliphatic methyl ketones containing α-methylene or α-methine groups and with enolates derived from α,α‘-dimethylene or α,α‘-dimethine ketones yield mono- or bis(diazeniumdiolate) products. Diazeniumdiolation occurs in the following order:  α-methine > α-methylene > α-methyl. The amount of the base used alters the extent of diazeniumdiolation and the course of the reaction. Mono- and bis(diazeniumdiolate)-substituted methyl ketones are cleaved in the presence of excess base before and after the subsequent diazeniumdiolation of the α-methyl group. Similar to the trihalogenated methyl groups in the base-assisted halogenation reactions of methyl ketones, the bis(diazeniumdiolate)-substituted α-methylene and α-methyl groups act as leaving groups in the presence of excess base. The reaction of nitric oxide with a (∼20:80, cis/trans) mixture of 2,6-cyclohexananone yields the cis and trans isomers of 2,6-dimethylcyclohexanone-2,6-bis(diazeniumdiolate) in 12.9% and 57.6% yield. Single-crystal X-ray diffraction data determined for potassium cis-2,6-dimethylcyclohexanone-2,6-bis(diazeniumdiolate), cis-14b, reveal that the N2O2- substituent is planar with considerable delocalization of a double bond over the anionic four-atom group. Except for one of the diazeniumdiolate products, namely, potassium propanoate 2,2-bis(diazeniumdiolate), 8b, all are stable in neutral and basic aqueous media. Compound 8b slowly decomposes in neutral aqueous solution releasing nitrous oxide and nitric oxide gases but is stable in basic aqueous media. Differential scanning calorimetry data measured for the diazeniumdiolate products indicate that they decompose exothermally with most of them undergoing explosive decomposition at moderately high temperatures (181−274 °C)

Multiplicity Control in the Polygeminal Diazeniumdiolation of Active Hydrogen Bearing Carbons: Chemistry of a New Type of Trianionic Molecular Propeller

Over a century ago, Traube reported the reaction of four nitric oxides with acetone and sodium ethoxide to yield sodium methanebis(diazene-N-oxide-N‘-hydroxylate) and sodium acetate. However, when this reaction is carried out in the presence of nitric oxide at slightly elevated pressures (35−40 psi), a product corresponding to the addition of six nitric oxides, sodium methanetris(diazene-N-oxide-N‘-hydroxylate), forms as the main product in addition to a trace of the previously observed sodium methanebis(diazene-N-oxide-N‘-hydroxylate) and sodium acetate. The corresponding potassium salts form when potassium hydroxide is employed as the base, while lithium hydroxide results in the formation of lithium methanebis(diazene-N-oxide-N‘-hydroxylate) exclusively. Nitric oxide reacts with 3,3-dimethylbutan-2-one in the presence of sodium and potassium hydroxide in methanol to yield sodium and potassium 3,3-dimethylbutan-2-one-1,1,1-tris(diazene-N-oxide-N‘-hydroxylate), respectively. In contrast, the reaction in the presence of lithium hydroxide forms lithium methanebis(diazene-N-oxide-N‘-hydroxylate) and lithium pivalate. The differential reactivity of nitric oxide with acetone and 3,3-dimethylbutan-2-one in the presence of the three bases is attributed to competing hydrolytic reactions of the acetyl and trimethylacetyl group-containing intermediates. A mechanism is proposed for the nitric oxide addition to active methyl groups in these reactions, where the product distribution between the di- and trisubstituted methanes is under kinetic control of the competing reactions. The products are characterized by NMR and IR spectroscopy, differential scanning calorimetry, and elemental analysis. Two differentially hydrated forms of potassium methanetris(diazene-N-oxide-N‘-hydroxylate) are characterized by single-crystal X-ray diffraction. From the metathesis reaction of the silver salt of methanetris(diazene-N-oxide-N‘-hydroxylate) with ammonium iodide, the corresponding ammonium salt is isolated in 59% yield, but only trace amounts of methylated products form in the reaction of the silver salt with methyl iodide. Density functional calculations (B3LYP/6-311++G**) are used to evaluate the bonding, ground-state structures, and energy landscape for the different conformers of methanetris(diazene-N-oxide-N‘-hydroxylate)3- trianion, a new type of a molecular propeller, and its corresponding triprotonated acid

sj-pdf-1-ems-10.1177_14690667221149498 - Supplemental material for Synthesis, characterization, and liquid injection field desorption ionization mass spectrometry analysis of pincer ligated group 6 (Cr, Mo, W) carbonyl complexes

Supplemental material, sj-pdf-1-ems-10.1177_14690667221149498 for Synthesis, characterization, and liquid injection field desorption ionization mass spectrometry analysis of pincer ligated group 6 (Cr, Mo, W) carbonyl complexes by Olivia L. Duletski, Navamoney Arulsamy and Michael T. Mock in European Journal of Mass Spectrometry</p

Synthesis of [(dfepe)Pt(Me)(NC₅F₅)]⁺B(C₆F₅)₄⁻, a Highly Active Ethylene Dimerization Catalyst

The synthesis of cationic adducts (dfepe)Pt(Me)(L)+ (dfepe = (C2F5)2PCH2CH2P(C2F5)2; L = MeCN, CO, C2H4, C5F5N, μ-Cl) are reported. Treatment of (cod)Pt(Me)Cl with AgSbF6 in acetonitrile followed by the addition of dfepe afforded (dfepe)Pt(Me)(CH3CN)+SbF6−. Addition of B(C6F5)3 to (dfepe)Pt(Me)(O2CCF3) in methylene chloride afforded the structurally characterized borane association product (dfepe)Pt(Me)[(O2CCF3)B(C6F5)3] in high yield. Attempts to displace the [(O2CCF3)B(C6F5)3]− anion with donor ligands resulted in loss of borane and regeneration of (dfepe)Pt(Me)(O2CCF3). Addition of the mesitylenium acid (1,3,5-C6H4Me3)+B(C6F5)4− to (dfepe)PtMe2 in methylene chloride at ambient temperatures resulted in chloride abstraction and the precipitation of the chloride-bridged dimeric complex [{(dfepe)Pt(Me)}2(μ-Cl)]+B(C6F5)4−, which has been structurally characterized. In contrast, treatment of (dfepe)PtMe2 with (1,3,5-C6H4Me3)+B(C6F5)4− in pentafluoropyridine at ambient temperature resulted in the precipitation of the structurally characterized pentafluoropyridine adduct [(dfepe)Pt(Me)(NC5F5)]+B(C6F5)4− in good yield. Exposure of [(dfepe)Pt(Me)(NC5F5)]+B(C6F5)4− to 1 atm of CO in o-difluorobenzene gave the carbonyl complex [(dfepe)Pt(Me)(CO)]+B(C6F5)4−. In marked contrast to previously reported platinum systems, [(dfepe)Pt(Me)(NC5F5)]+B(C6F5)4− is a very active ethylene dimerization catalyst at ambient temperature (600 psi ethylene, 22 °C in ortho-difluorobenzene, 150 turnovers h−1). The ethylene adduct [(dfepe)Pt(Me)(η2-C2H4)]+B(C6F5)4− has been spectroscopically characterized at −20 °C

sj-cif-3-ems-10.1177_14690667221149498 - Supplemental material for Synthesis, characterization, and liquid injection field desorption ionization mass spectrometry analysis of pincer ligated group 6 (Cr, Mo, W) carbonyl complexes

Supplemental material, sj-cif-3-ems-10.1177_14690667221149498 for Synthesis, characterization, and liquid injection field desorption ionization mass spectrometry analysis of pincer ligated group 6 (Cr, Mo, W) carbonyl complexes by Olivia L. Duletski, Navamoney Arulsamy and Michael T. Mock in European Journal of Mass Spectrometry</p

Synthesis and Thermal Decomposition Studies of New Nitroso- and Nitrodicyanomethanide Salts

The lithium, barium, ammonium, and guanidinium salts of nitrosodicyanomethanide ([ONC(CN)2]-), and the lithium, sodium, barium, ammonium, guanidinium, and hydrazinium salts of nitrodicyanomethanide ([O2NC(CN)2]-) are synthesized and characterized by infrared, UV−vis and 13C NMR spectroscopy, and elemental analysis. Four of them, namely, [NH4][ONC(CN)2], Ba[ONC(CN)2]2(H2O), [NH4][O2NC(CN)2], and Ba[O2NC(CN)2](Cl)(H2O)2, have also been characterized by single-crystal X-ray diffraction data. The structural data reveal that the two anions possess comparable structural features irrespective of the nature of the cation. The N−O bond distances in [NH4][ONC(CN)2] and Ba[ONC(CN)2]2(H2O) are similar at 1.286(2) and 1.292(4) Å, respectively, and the anion possesses a nearly planar geometry. Nitrodicyanomethanide anions in the crystals of [NH4][O2NC(CN)2] and Ba[O2NC(CN)2](Cl)(H2O)2 are also nearly planar with average N−O bond distances of 1.258(2) and 1.252(5) Å, respectively. In Ba[ONC(CN)2]2(H2O), the nitrosodicyanomethanide anion binds a single metal center through the nitrogen and oxygen atoms of the nitroso group while also binding two other metal centers through the cyano nitrogen atoms. In Ba[O2NC(CN)2](Cl)(H2O)2, the nitrodicyanomethanide anion coordinates to the metal center only through the cyano nitrogen atoms. The thermal properties of the new compounds together with those of the known sodium, potassium, and silver salts of nitrosodicyanomethanide and the potassium and silver salts of nitrodicyanomethanide are examined by differential scanning calorimetry (DSC). The DSC data reveal that the two series of compounds undergo exothermic decomposition releasing 240−690 cal/g. The alkali metal, silver, and barium salts decompose at higher temperatures (>200 °C), whereas the nitrogenous cationic salts decompose at lower temperatures, indicating that the thermal behavior of the two anions can be significantly altered by choosing appropriate cations

Photophysical and Electrochemical Characterization of a Helical Viologen, <i>N</i>,<i>N</i>′‑Dimethyl-5,10-diaza[5]helicene

The first helical viologen (4,4′-bipyridinium salt) has been prepared and characterized. Its reduction to the radical cation at −0.22 V vs SCE makes it the most easily reduced redox-active helicene known. It exhibits absorption at 397 nm for the S₁ ← S₀ transition, and it is luminescent allowing measurement of both its singlet (59.3 ± 0.1 kcal/mol) and triplet (54 ± 1 kcal/mol) energies. In contrast to neutral helicenes, it is not aromatic π-stacked in the crystal and has a shortest interdication distance of 4.977 Å. Its racemization barrier is calculated to be a sensitive function of its redox state

Investigation of Iridium ^CF₃PCP Pincer Catalytic Dehydrogenation and Decarbonylation Chemistry

The iridium fluorinated pincer complex (^CF₃PCP)­Ir­(cod) (^CF₃PCP = 2,6-C₆H₃(CH₂P­(CF₃)₂)₂) catalyzes hydrogen transfer from cyclooctane (coa) to <i>tert</i>-butylethylene (tbe) in 1/1 coa/tbe at 200 °C to give cyclooctene (coe) and neohexane (tba) at an initial rate of 40 TO h^–1. In 5/1 coa/tbe, higher initial activity (155 TO h^–1) and higher turnovers (2580 TON’s after 1450 min) are found. Samples of 95% tbe contain significant amounts of isoprene (2-methyl-1,3-butadiene), which reacts with (^CF₃PCP)­Ir­(cod) to initially form (^CF₃PCP)­Ir­(isoprene). Alkene inhibition studies show that (^CF₃PCP)Ir is only modestly inhibited (67% reduced initial activity) in the presence of 800 equiv of added coe. Unlike donor pincer systems, no decrease in activity is noted under 1 atm of N₂ or in the presence of excess water. Hydrogenation of (^CF₃PCP)­Ir­(L) (L = cod, isoprene) did not produce (^CF₃PCP)­Ir­(H)_<i>x</i> but instead afforded the first example of the unusual aryl-bridged bimetallic complex [(μ-1κ²(<i>P</i>,<i>C</i>),2κ²(<i>P</i>′,<i>C</i>)-^CF₃PCP)­Ir­(H)₂]₂(μ-^CF₃PCPH)­(μ-H), which has been isolated and crystallographically characterized. Ir­(I) pincer complexes (^CF₃PCP)­Ir­(L) (L = MeP­(C₂F₅)₂, CO, dfepe (dfepe = (C₂F₅)₂PCH₂CH₂P­(C₂F₅)₂)) also serve as moderately active aldehyde decarbonylation catalyst precursors for 2-naphthaldehyde with similar activities in diglyme (1.7 TO h^–1, 152 °C) and in 1,4-dioxane (0.052 TO h^–1, 94 °C). The catalyst resting states are the corresponding five-coordinate carbonyl complexes (^CF₃PCP)­Ir­(MeP­(C₂F₅)₂)­(CO), (^CF₃PCP)­Ir­(CO)₂, and [(^CF₃PCP)­Ir­(CO)]₂(μ-dfepe). DFT studies indicate that the preferred catalyst resting state for alkane dehydrogenation, (^CF₃PCP)­Ir­(cod), can be ascribed to the lower steric requirements of the CF₃-substituted pincer ligand