Nitroso Oxygen Atom Research Articles

Trinuclear and tetranuclear manganese clusters derived from cyano(imino(methoxy)methyl)nitrosomethanide (cmnm)

Three manganese clusters have been synthesised via the reaction of MnII with cyano(imino(methoxy)methyl)nitrosomethanide (cmnm), obtained from the in situ nucleophilic addition of MeOH to dicyanonitrosomethanide (dcnm). X-ray crystallographic studies show that the complex [MnII3(cmnm)6]·MeOH (1) is a linear trinuclear species, with a central octahedral and two outer trigonal-prismatic manganese(II) ions. Two mixed-valent tetranuclear complexes [MnII2MnIII2O2(cmnm)4Cl2(MeOH)6] (2) and [MnII2MnIII2O2(cmnm)4Cl2(MeOH)4(pzH)2]·2MeOH (3) (pzH=pyrazole) contain two MnII and two MnIII ions in butterfly-type structures, with the six-coordinate ‘body’ MnIII ions bridged to the seven-coordinate ‘wingtip’ MnII ions by μ3-O2− and by nitroso oxygen atoms of the cmnm ligands. The formation of the trinuclear and tetranuclear manganese clusters is dependent on the stoichiometry used in the reactions. Solid state DC magnetic susceptibility studies on complexes 1 and 3 reveal that antiferromagnetic interactions are dominant within the clusters. Fits of the data reveal an S=5/2 ground state for 1 and a S=0 ground state for 3, with several close lying excited states found in both cases.

Synthesis and magnetic properties of a series of 3d/4f/3d heterometallic trinuclear complexes incorporating in situ ligand formation

The dicyanonitrosomethanide (dcnm) ligand undergoes an in situ transition metal promoted nucleophilic addition of methanol to a nitrile group to form cyano(imino(methoxy)methyl)nitrosomethanide (cmnm) in the formation of the 3d/4f heterometallic complexes (Me4N)[{Ni(cmnm)3}2Ln(cmnm)2] (1Ln; 1Ln=1La, 1Ce, 1Pr, 1Nd, 1Sm). A change in the counter-ions of the metal and ligand salts employed under alternate reaction conditions results in the formation of (Et4N)2[{Ni(cmnm)3}2Ln(dcnm)2](ClO4) (2Ln; 2Ln=2La, 2Ce), in which unreacted dcnm ligands are coordinated to the central lanthanoid. In both types of complexes three cmnm ligands chelate to a nickel metal centre to form a [Ni(cmnm)3] metalloligand. Two of these metalloligands are then bound to a central lanthanoid via the nitroso oxygen atoms, resulting in a trinuclear complex in which each nickel cation is connected to the lanthanoid by three bridging nitroso groups. Variable temperature magnetic susceptibilities on these {Ni(S=1), Ln(f0 to f5), Ni(S=1)} spin systems reveal very weak to zero Ln–Ni or Ni–Ni exchange coupling with the thermal depopulation between Stark levels on the Ln centres being of similar magnitude, and the Ni2Ce and Ni2Pr cases giving strongest evidence for exchange coupling.

ChemInform Abstract: Novel Generation of Azomethine Imines from α-Silylnitrosamines by 1,4-Silatropic Shift and Their Cycloaddition.

Abstract Novel and facile generation of azomethine imines from α-silylnitrosamines and subsequent cycloaddition with dipolarophiles leading to a variety of pyrazole derivatives have been developed. The key to the reaction is a 1,4-silatropic shift caused by strong affinity of the nitroso oxygen atom toward the silicon atom. Thus, α-silylnitrosamines are treated with 1 equiv. of dipolarophiles in refluxing toluene for 1 h to give pyrazole derivatives in good to excellent yields.

Solvent polarity and hydrogen-bonding effects on the nitrogen NMR shieldings of N-nitrosamines and DFT calculations of the shieldings of C-, N-, and O-nitroso systems

High-precision nitrogen NMR shieldings, bulk susceptibility corrected, are reported for dimethyl- N-nitrosamine ( I) and diethyl- N-nitrosamine ( II) in a variety of solvents which represent a wide range of solvent properties from the point of view of polarity as well as hydrogen bond donor and acceptor strength. The observed range of solvent-induced nitrogen shielding variations of ( I) and ( II) is significant for the amino-type nitrogens, up to about 16 ppm, and originates essentially from the deshielding effect of the increasing polarity of solvent. On the other side, the nitroso nitrogen shieldings reveal an even stronger response to solvent effects, within about 20 ppm, but in this case the increasing polarity and hydrogen bond donor strength of solvent produce enhanced shielding. DFT quantum-mechanical calculations using the GIAO/B3PW91/6-311++G** approach and geometry optimizations employing the same basis set and hybrid density functionals show an excellent correlation with the experimental data on C-, N-, and O-nitroso moieties and reproduce not only major changes but also most of the subtle variations in the experimental nitrogen shieldings of the nitroso systems as a whole. A combination of the calculations involving the corresponding N and O-protonated species and the trends observed in the solvent-induced nitrogen shielding variations shows clearly that the prime acceptor site for hydrogen bonding is the nitroso oxygen atom.

Preparation of pyridine-N-glucuronides of tobacco-specific nitrosamines.

Nicotine and cotinine are metabolized to pyridine-N-glucuronides in humans. This suggests that the analogous metabolites of the carcinogenic nicotine-related nitrosamines N'-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) should also be formed in people exposed to these compounds via tobacco products. We describe the synthesis of the appropriate pyridine-N-glucuronides: pyridyl-N-beta-D-glucopyranuronosyl-N'-nitrosonornicotinium inner salt (NNN-N-Gluc, 8), 4-(methylnitrosamino)-1-(3-pyridyl-N-beta-D-glucopyranuronosyl)-1-butanonium inner salt (NNK-N-Gluc, 9), and 4-(methylnitrosamino)-1-(3-pyridyl-N-beta-D-glucopyranuronosyl)-1-butanolonium inner salt (NNAL-N-Gluc, 10). The starting material, methyl 2,3,4-tri-O-acetyl-1-bromo-1-deoxy-alpha-D-glucopyranuronate (1), is prepared in two steps from glucuronolactone. Reactions of 1 with racemic NNN (2), NNK (3), or racemic NNAL (4) are carried out with no solvent and the crude products are deprotected by treatment with base, giving the desired N-glucuronides 8-10 in 5-7% overall yield after HPLC purification. The N-glucuronides were characterized by (1)H NMR, including COSY and NOESY spectra, and by MS and MS/MS. NNN-N-Gluc exists as a 52:48 ratio of (E)- and (Z)-rotamers, which were partially separated by HPLC. This ratio was surprisingly similar to the (E):(Z) ratio for NNN itself suggesting hydrogen bonding of the (Z)-nitroso oxygen atom to the 2' '-hydroxyl group of the glucuronide moiety. Partial HPLC separations of the (E)- and (Z)-rotamers of NNK-N-Gluc and the (E)- and (Z)-rotamers as well as the (R)- and (S)-diastereomers of NNAL-N-Gluc were also achieved. The standards prepared in this study as well as the HPLC conditions developed for their separation will be important for analysis of these compounds in human urine.

Crystallographic and Spectroscopic Evidence of O-Bonding in 3d-MetaI Dicyanomethanidonitrite Complexes

Abstract The coordination of the dicyanomethanidonitrite group through the nitroso oxygen atom in the tetrakis(pyridine) complexes [M{ONC(CN)2}2(py)4], M = Ni, Co, Cu, and in the bis(pyridine) complex [Cu{ONC(CN)2}2(py)2] was proved by X-ray crystallography of the Ni11 complex and re-evaluated infrared spectra. The Ni11 and Co11 complexes exhibit almost octahedral structures composed of four pyridine nitrogen atoms and two oxygen atoms of dicyanomethanidonitrite ions. Both copper(II) complexes display a considerable axial distortion of the pseudooctahedral arrangement. In the bis(pyridine) Cu11 complex the ONC(CN)2 groups are involved in the bridging function by use of the oxygen and nitrile nitrogen atoms.

Novel generation of azomethine imines from α-silylnitrosamines by 1,4-silatropic shift and their cycloaddition

Novel and facile generation of azomethine imines from α-silylnitrosamines and subsequent cycloaddition with dipolarophiles leading to a variety of pyrazole derivatives have been developed. The key to the reaction is a 1,4-silatropic shift caused by strong affinity of the nitroso oxygen atom toward the silicon atom. Thus, α-silylnitrosamines are treated with 1 equiv. of dipolarophiles in refluxing toluene for 1 h to give pyrazole derivatives in good to excellent yields.

The Phenomenon of Intramolecular Attractive S---O Interactions: Synthesis and Structure of (1,10-Phenanthroline)copper(II) Complexes with Isonitroso-(4-methylthiazol-2-yl)acetamide and Isonitroso-(4-methylthiazol-2-yl)-(benzothiazol-2-yl)methanide

Abstract Isonitroso-(4-methylthiazol-2-yl)acetamide H (L1), isonitroso-(4-methylthiazol-2-yl)(benzo-thiazol-2-yl)methanide H(L2) and their copper(II) complexes of composition [Cu(Phen){L1}(ClO4)] (1) and [Cu(Phen){L2}Cl]*C2H5OH (2) have been prepared. Crystal and molecular structures of the complexes have been determined from X-ray diffractioon data (1: monoclinic, space group P21/c, with a = 11.611(2), b = 10.259(2), c = 17.869(4) Å, β = 104.67(3)°, V = 2059.1(7) Å3, Z = 4; R1 = 0.046 for the 2522 unique reflections with I > 2σ(I). 2: triclinic, space group P1̄, with a = 8.351(1), b = 10.876(1), c = 14.891(2) Å, a = 96.170(8)°, β = 94.201(9)°, γ = 106.721(9)°, V = 1280.1(2) Å3, Z = 2; R1 = 0.034 for the 4038 unique reflections with I > 2σ(I)). In the structure of 1 the coordination polyhedron of Cu2+ is a distorted square pyramid with an oxygen atom of the CIO4 counter anion in the apex (C u -O 2.505(3) Å); in complex 2 the copper atom adopts fivefold coordination of a slightly distorted trigonal-bipyramidal geometry with a chlorine atom in the equatorial plane (Cu-Cl 2.3504(9) A). Ethanol of crystallization gives rise to a hydrogen bond at the chlorine atom. In both structures the oximic anions are coordinated to the metal center in a bidentate chelate manner via the nitrogen atom of the nitroso group and the carbonyl oxygen atom (1) or via the benzothiazole nitrogen atom (2) (Cu-O, Cu-N in the range 1.963(2) -2.031 (2) Å). The thiazole group of the ligands takes no part in the coordination. The nitroso oxygen atoms possess short intramolecular contacts with thiazole sulphur atoms, with d(S--- O) at 2.605(3) (1) and 2.676(3) A (2), which may be attributed to a strong intraligand interaction.

Synthesis, Infrared and X-Ray Studies of Diphenyltellurium(IV) Nitrosocarbamylcyanmethanides. X-Ray Evidence for Stability of a Tritelluroxane Fragment -Ph2Te-O-Ph2Te-O-Ph2Te-

Abstract Diphenyltellurium(IV) derivatives of the types Ph2Te{ACO}2 (1), Ph4Te2O{ACO}2 (2) and Ph6Te3O2{ACO} (3) (ACO = nitrosocarbamylcyanmethanide -ONC(CN)C(O)NH2) have been prepared. The IR spectroscopic data reveal that the ambidentate ligands are coordinated to the tellurium(IV) atom in a monodentate manner via the nitroso oxygen atom. The crystal and molecular structure of 3 has been determined from X-ray diffraction data (triclinic, space group P1̅ with a = 12.382(2), 6=13.100(2), c = 14.944(3) Å, a = 87.74( 1), β = 85.04(2), 7 = 66.29( 1)°, V = 2211.0 A , Z = 2, R = 0.040). The structure is made up of unsymmetric molecules, in which the tellurium atoms are linked by oxo bridges to form chains Te-O-Te-O-Te (d(Te-O) ca. 1.94-2.09 A). The Te-0 (nitroso group) bond lengths are in the range 2.33 - 2.36 Å

Stereoselectivity in the microsomal conversion of N-nitrosodimethylamine to formaldehyde

The possibility that N-nitrosodimethylamine (NDMA) might be metabolized preferentially at either the syn (relative to the nitroso oxygen) or the anti methyl group has been examined by comparing the rates of formaldehyde production when unlabeled NDMA, its fully deuteriated analogue (NDMA-d6), and (Z)- or (E)-N-nitrosomethyl(methyl-d3)amine (NDMA-d3) were incubated in turn at concentrations of 0-2.4 mM with acetone-induced rat liver microsomes. The Km values for the conversion of (Z)- and (E)-NDMA-d3 to formaldehyde were identical to each other within experimental error (32 +/- 2 and 35 +/- 1 microM, respectively) but different from those for NDMA (24 +/- 6 microM) and NDMA-d6 (116 +/- 3 microM); similar Vmax values were observed for the four isotopic variants [7.5-8.1 nmol/(mg of protein.min)]. The observed similarity of kinetic parameters for (Z)- and (E)-NDMA-d3 suggested that the isotopic composition of the methyl group is an energetically more important determinant of its rate of oxidation at the NDMA demethylase active site than is its orientation relative to the nitroso oxygen atom. The absence of syn vs anti stereospecificity was confirmed via product isolation studies, in which the formaldehyde generated from each of the four isotopomers was trapped as the dimedone adduct and assayed for deuterium content by mass spectrometry; again, a strong preference for metabolism at CH3 vs CD3 regardless of stereochemistry was observed, though the data on CH2O generation suggested that there may be a slight net excess of anti attack. The results indicate that the microsomal enzymes employed display little regioselectivity in metabolizing the syn vs anti methyl groups of NDMA.

Electrochemical transformation of N-nitrosodialkylamines into N-nitramines and .BETA.-ketonitrosamines.

Controlled potential electrolysis, based on the results of cyclic voltammetry, of simple dialkylnitrosamines such as N-nitrosodibutylamine and N-nitrosodicyclohexylamine in acetonitrile at a glassy carbon electrode resulted in the formation of the corresponding nitramines as the major products together with β-ketonitrosamines in which the carbonyl group is on the same side of the nitroso-oxygen atom. With N-nitrosopiperidine, one derived from a cyclic amine, N-nitropiperidine was formed similarly but the β-oxidized nitrosamine was not detected in the electrolysis solution. In deoxygenated acetonitrile, neither the nitramines nor the β-ketonitrosamines were obtained from the electrolysis.

ChemInform Abstract: ORIGIN OF THE OXYGEN ATOM IN THE NITROSOMESITYLENE FORMED BY THE OXIDATION OF MESIDINE WITH FREMY′S SALT

Chemischer InformationsdienstVolume 7, Issue 42 Preparative Organic Chemistry ChemInform Abstract: ORIGIN OF THE OXYGEN ATOM IN THE NITROSOMESITYLENE FORMED BY THE OXIDATION OF MESIDINE WITH FREMY′S SALT TOMOJI TAKAHASHI, TOMOJI TAKAHASHISearch for more papers by this authorHIROSHI MINATO, HIROSHI MINATOSearch for more papers by this authorMICHIO KOBAYASHI, MICHIO KOBAYASHISearch for more papers by this author TOMOJI TAKAHASHI, TOMOJI TAKAHASHISearch for more papers by this authorHIROSHI MINATO, HIROSHI MINATOSearch for more papers by this authorMICHIO KOBAYASHI, MICHIO KOBAYASHISearch for more papers by this author First published: October 19, 1976 https://doi.org/10.1002/chin.197642133Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume7, Issue42October 19, 1976 RelatedInformation

Origin of the Oxygen Atom in the Nitrosomesitylene Formed by the Oxidation of Mesidine with Fremy’s Salt

Abstract The mechanism of the oxidation of aromatic amines with Fremy’s salt was investigated by use of 18O-labelled compounds. It was shown that the nitroso-oxygen atom originates not from water but from the nitroxide oxygen and sulfonate oxygen atoms of Fremy’s salt.

Crystal and molecular structure of a diradical, 1,3-dinitro-4,6-di[3-(2,2,5,5-tetramethyl)-pyrrolidinyl-N-oxide]aminobenzene monohydrate

The crystal structure of 1,3-dinitro-4,6-di[3-(2,2,5,5-tetramethyl)pyrrolidinyl-N-oxide] aminobenzene monohydrate has been determined by single-crystal X-ray diffraction methods using the 1793 unique reflections for which 3 ° 3σ(I), and refined to a conventionalR index of 0.032. Counter methods using MoKα radiation were employed. Crystals form in the triclinic space groupP¯1 (No. 2) witha = 16.160(10),b = 11.686(6),c = 7.211(5) A, α = 95.87(5) °, β = 98.67(5) °, and γ = 107.74(4) °. All hydrogen atom positions were determined. Intramolecular hydrogen-bonding between the nitro and amino groups has, in part, caused the central 20 atoms of the molecule, counting hydrogen atoms, to lie in an approximate plane. The benzene ring is distorted by its substituents to the symmetrymm2(C2v). The internal angles of the benzene ring range from 116.1 ° to 124.7 ° (esd = 0.3 °), and its bonds are between 1.368 A and 1.436 A (esd = 0.004 A) in length. Four of the five atoms in each pyrrolidine ring are nearly coplanar; the remaining atom, the carbon bonded to the amine nitrogen in each case, lies approximately 0.53 A from the corresponding plane. The best four-atom planes of the two pyrrolidine rings are each near to perpendicular to the central plane, giving the molecule a lobster-like appearance; they are each rotated approximately 15 °, in opposite senses, from perpendicular. The intramolecular distance between the two pyrrolidine nitrogen atoms, to which the unpaired charges can be assigned, is 7.68 A. One of the nitroso oxygen atoms is hydrogen-bonded by two symmetry-equivalent water molecules. The inversion center necessitates that the remaining hydrogen atoms of these water molecules both hydrogen-bond to a symmetry-equivalent nitroso oxygen atom to give a hydrogen-bonded four-oxygen ring.

The crystal and molecular structure of 2-(N-nitrosomethylamino)acetamide

Crystals of 2-(N-nitrosomethylamino)acetamide are monoclinic, space group P2~/n, with a = 16-681 (30), b=4774 (5), c= 14318 (15) A and fl=92.95(20) °. Each unit cell contains four molecules of the E isomer and four of the Z isomer. The structural model was refined to R = 0.044 for 1184 independent reflections measured using an automatic diffractometer. Hydrogen bonds from amide groups to carbonyl or nitroso oxygen atoms connect the molecules in sheets parallel to (100).

The crystal structure of ethyl p-azoxybenzoate

The low-temperature form (solid I) of the smectogenic compound ethyl p-azoxybenzoate (C18H18N2Os) is stable below 90 °C. The triclinic unit cell of space group P] and dimensions a = 7.56 + 0.02, b-1835 _+ 0.07, c= 6.28 + 0.01 A, ¢¢= 94.38 ° + 0.30 °, ,8= 97.21 _+ 0.31 °, and y = 83.97 ° + 0.25 ° contains two molecules and has a calculated density of 1.325 g.cm-3. The observed density is 1.315 + 0.013 g.cm-3. Integrated intensities were measured at room temperature by a 20--~ scan on a four-circle diffractometer equipped with a post-diffraction monochromator and scintillation detector. The crystal structure was refined by full-matrix least-squares methods with 1460 independent reflections to a final R index of 0093. The molecules are nearly planar (the normals to the planes of the two benzene rings diverge by only 0-5 °) and are packed in a parallel array, as contrasted with the imbricated structure which has been observed for several nematogenic crystalline solids. The carbonyl and nitroso oxygen atoms are all in the cis conformation, resulting in a large dipole component in the plane of the molecule and perpendicular to its long axis. It is speculated that this feature of the molecular structure may be characteristic of smectogenic compounds.

Abnormal addition of free radicals to sterically hindered nitrosobenzenes

1-Cyano-1-methyl- and 1-methoxycarbonyl-1-methyl-ethyl radicals reacted with 2,4,6-tri-t-butylnitrosobenzene (I) to give abnormal 1,6-addition products, 1-(1-cyano-1-methylethoxyimino)-4-(1-cyano-1-methylethyl)-2,4,6-tri-t-butylcyclohexa-2,5-diene (III) and the corresponding methoxycarbonyl derivative (IV), respectively. We suggest that the reactions proceed via anilino-radicals (II) formed by attack of the radical on the nitroso-oxygen atom. The reaction of 2-methyl-4,6-di-t-butylnitrosobenzene (VI) with the 1-cyano-1-methylethyl radical afforded N-isopropylidene-2-methyl-4,6-di-t-butylaniline N-oxide (VII) and 3-(1-cyano-1-methylethyl)-5,7-di-t-butyl-2,1-benzisoxazole (VIII). 2,5-Di-t-butylnitrosobenzene reacted with 1-cyano-1-methylethyl radicals to produce a normal addition product (XI).

A 13C Fourier nuclear magnetic resonance study of conformational effects in some N-nitroso-compounds

The carbon-13 “Fourier” n.m.r. spectra of a series of N-nitrosamines and N-nitrosoanilines have been obtained and show that the carbon shifts in these systems are dependent on the orientation of the nitroso-oxygen atom: definitive evidence for the coplanarity of the two π-systems in N-methyl-N-nitrosoaniline is presented.