Reaction of Imidazoles with Cyanogen Bromide: Cyanation at N 1 or Bromination at C 2?

1999 ◽  
Vol 52 (3) ◽  
pp. 159 ◽  
Author(s):  
Peter B. W. McCallum ◽  
M. Ross Grimmett ◽  
Allan G. Blackman ◽  
Rex T. Weavers
Keyword(s):  
Nitrogen Atom ◽  
Cyanogen Bromide ◽  
Lone Pair ◽  
Alkyl Substituent ◽  
Acetonitrile Solution ◽  
Crystal Data ◽  
X Ray ◽  
Ring Nitrogen ◽  
Ring Nitrogen Atom

The reaction in acetonitrile solution of a number of imidazoles(1H-, 1-methyl-, 2-methyl-, 4-methyl-, 1,2-, 1,4- and1,5-dimethyl-, 1-ethyl-, 1-benzyl- and 1-butyl-imidazole) and imidazolecomplexes([Co(NH3)5(imH)](ClO4)3,[Co(NH3)5(im)](ClO4)2 and[Co(NH3)5(1-Meim)](ClO4)3) with BrCN has beenstudied. Those imidazoles bearing an N-alkyl substituent and having a hydrogenat C2 react to give the 2-bromo products, while the N-H imidazoles react togive N-cyano derivatives. The product(s) from thereaction of 1,2-dimethylimidazole with BrCN could not be characterized. Of thecomplexes, only[Co(NH3)5(im)](ClO4)2 reacts, giving the 2-bromoproduct. Our observations suggest a lone pair on a ring nitrogen atom isnecessary for an imidazole to react with BrCN, and a possible mechanism issuggested. The X-ray structure of 2-methylimidazole-1-carbonitrile isreported. Crystal data (–143°C) forC5H5N3:monoclinic, P21/c, a10·201(5), b 7·110(3),c 7·227(3) Å, β 100·47(2)°,V 515·4(4) Å 3 , Z 4,dcalcd 1·380 gcm¯3 . Refinement of the structure converged withR1 0·0444 for 1183reflections with Fo >4F(Fo) andwR2 0·1259 for all 1278data.

Übergangsmetallkomplexe mit Nitroxidradikalen: Palladium-, Platin-, Pentamethylcyclopentadienyl-rhodium- und -iridium-Komplexe sowie α-Aminocarboxylatkomplexe mit Donor-haltigen Derivaten des 2,5-Dihydroimidazol-l-oxyls / Transition Metal Complexes of Nitroxide Radicals, Palladium, Platinum, Pentamethylcyclopentadienyl Rhodium and Iridium Complexes, and α-Aminocarboxylate Complexes with Derivatives of 2,5-Dihydroimidazole-l-oxyls

1998 ◽  
Vol 53 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Frank Hintermaier ◽  
Sylvia Helding ◽  
Leonid B. Volodarsky ◽  
Karlheinz Sünkel ◽  
Kurt Polbom ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Molecular Structures ◽  
Iridium Complexes ◽  
X Ray Diffraction ◽  
Chelate Complexes ◽  
X Ray ◽  
Ring Nitrogen ◽  
Derivatives Of ◽  
Ring Nitrogen Atom ◽  
Palladium Platinum

2,5-Dihydroimidazoline-l-oxyl radicals I, II with imino substituents coordinate to Pd(II) and Pt(II) complexes with formation of the N,N chelate complexes 1-6. With oxygen containing substituents either monodentate N-coordination to give 8 or N ,O chelate formation to give 9 takes place, depending on the position of the oxygen atom relative to the ring nitrogen atom. With radicals III that also have the second ring nitrogen atom oxidized and the Rh(III) or Ir(III) complexes [Cp*MCl2]2 the O , O chelates 11 -13 could be obtained, while with Na2PdCl4 the heterocycle was destroyed with formation of a N,N chelate complex 10 of an α-nitrosooxime ligand. The orthopalladated 2,2,5,5 tetramethyl-4-phenyl-2,5-dihydroimidazoline-l-oxyl complex 7a reacts with several a-amino acidates under splitting of the dichloro bridge with formation of the C,N/N,O-bis-chelate complexes 7b-f. The molecular structures of 2 and 10 were determined by X-ray diffraction.

Structures of 4-Iminopyrido[1,2-a]pyrimidines, Pyrido[1,2-a]pyrimidin-4-ones, Pyridopyrimidinium Olates, and Thiazolo[3,2-a]pyrimidine Analogues

2012 ◽  
Vol 65 (4) ◽  
pp. 371 ◽  
Author(s):  
Paul V. Bernhardt ◽  
Curt Wentrup
Keyword(s):  
Nitrogen Atom ◽  
Ring Opening ◽  
Normal Range ◽  
X Ray ◽  
X Ray Crystallography ◽  
Structural Peculiarities ◽  
Ring Nitrogen ◽  
Structure Correlation ◽  
Pyrimidine Analogues ◽  
Ring Nitrogen Atom

The Structure-Correlation Principle of Bürgi and Dunitz is invoked in an analysis of the structures of 2-chloro-8-methyl-4-(2-(4-picolinyl)imino-4H-pyrido[1,2-a]pyrimidine 8, 7-chloro-5-(2-thiazolyl)imino-5H-thiazolo[3,2-a]pyrimidine 9, 2-methylamino-4H-pyrido[1,2-a]pyrimidin-4-one 10, 7-methylthio-5H-thiazolo[3,2-a]pyrimidin-5-one 11, 2,3-dihydro-7-methylthio-5H-thiazolo[3,2-a]pyrimidin-5-one 12, and 1-methyl-2-[(o-tert-butylphenyl)imino]-1,2-dihydropyrido[1,2-a]pyrimidin-1-ium-4-olate 13, which have been determined by X-ray crystallography. The most notable structural peculiarities are the long ‘amidine’ and ‘amide’ C–N bonds (1.40–1.50 Å) and the tilting of the ‘amidine’ C=N and ‘amide’ C=O groups towards a ring nitrogen atom (NCX = 114–118°). Also the ‘amidine’ C=N (1.28 Å) and ‘amide’ C=O bonds (1.22–1.24 Å) are long, i.e. in the normal range for resonance-stabilized amidines and amides in spite of the lack of such resonance in these compounds. These features mimic the transition states for ring opening to ketenes. The long amidine and amide C–N bonds and acute NCX angles are in accord with the observed thermal ring opening to ketenimines and ketenes, respectively.

X-Ray Structure, Electrochemical and Electronic Spectroscopic Examination of Cobaloximatic Acid: Hydro-trans-diiodobis(ethanedioximato(1-)-N,N′)cobaltate(III). Extended Intermolecular O-H-O Bridging in the Solid

1993 ◽  
Vol 48 (10) ◽  
pp. 1360-1364
Author(s):  
Michel Mégnamisi-Bélombé ◽  
Irene Jokwi ◽  
Emmanuel Ngameni ◽  
Robert Roux ◽  
Bernhard Nuber
Keyword(s):  
Room Temperature ◽  
Strong Acid ◽  
Acetonitrile Solution ◽  
Monoclinic Space Group ◽  
Coordination Geometry ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Acidic Proton ◽  
Spectroscopic Examination

The structure of the cobaloximatic acid, hydro-trans-diiodobis(ethanedioximato(1-)-N,N′)cobaltate(III), has been determined by X-ray diffraction. Crystal data: C4H7CoI2N4O4, Mr = 487.87; monoclinic space group P21/a (C2h5 ); a = 10.795(7), b = 9.003(7), c = 11.881(6) Å; β = 97.29(6)°; V = 1145.35 Å3; Z = 4; dc = 2.83 Mg m-3. Rw (R) = 3.6 (3.9)% for 3064 observed independent reflections and 148 parameters. The coordination geometry around CoIII is a distorted (4 + 2) octahedron of four chelating equatorial N atoms and two apical iodides. The compound is most adequately formulated as a monovalent strong acid: H(Co(GH)2I2) (GH- = ethanedioximate or glyoximate). The H atoms of the oxime groups are involved in the usual intramolecular, as well as in much stronger intermolecular O-H-O bridgings (O ••• Ointramol = 2.613-2.631, O ••• Ointramol = 2.454 A). The “acidic” H atom of each molecule participates in the intermolecular bridging which extends throughout the structure, and propagates nearly parallel to the [101] crystallographic direction. The redox properties of the present compound were examined by cyclic voltammetry in acetonitrile solution at room temperature. Redox waves attributed to the reduction of CoIII and to the oxidation of I- were observed, along with a wave which may be linked to the reduction of the “acidic” proton

Synthese und Kristallstruktur von [Na-15-Krone-5][MoF5 (NCl)]

1988 ◽  
Vol 43 (9) ◽  
pp. 1125-1129 ◽  
Author(s):  
Dieter Fenske ◽  
Karin Völp ◽  
Kurt Dehnicke
Keyword(s):  
Crown Ether ◽  
Nmr Spectra ◽  
Bond Angle ◽  
Ion Pairs ◽  
Sodium Ion ◽  
Acetonitrile Solution ◽  
Crystal Data ◽  
X Ray ◽  
Data Space ◽  
Ether Molecule

Abstract [Na-15-Crown-5][MoF5(NCl)] has been prepared as yellow crystals by the reaction of NaF with MoF4(NCl) in the presence of 15-crown-5 in acetonitrile solution. The compound was charac­terized by its IR and 19F NMR spectra as well as by an X-ray structure determination. Crystal data: space group P21/n, Z = 4 (3736 observed, independent reflexions, R = 0.034). Lattice dimensions at -70 °C: a = 823.5(4). b = 1612.2(9), c = 1383.4(8), β = 99.35(3)°. The compound forms ion pairs, in which the sodium ion is seven-coordinated by the oxygen atoms of the crown ether molecule and by two fluorine ligands of the [MoF5(NCl)]- unit with Na-F distances of 228.3 and 249.6 pm. The Mo=N-Cl group of the anion is nearly linear (bond angle 175.8°) with bond lengths MoN = 172.9 and NCl = 161.8 pm.

scholarly journals Exploring the Isomer Dependent SERS Spectra of (diphenylphosphoryl)(pyridin-2, -3, and -4-yl)methanol Adsorbed on Gold Nanocolloids

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Ewa Pięta ◽  
Edyta Proniewicz ◽  
Bogdan Boduszek ◽  
Tomasz K. Olszewski ◽  
Younkyoo Kim ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Adsorption Process ◽  
Gold Surface ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Ring Nitrogen ◽  
Derivatives Of ◽  
Ring Nitrogen Atom ◽  
Surface Changes

The surface-enhanced Raman scattering (SERS) spectra of three aminophosphonate derivatives of pyridine: (diphenylphosphoryl)(pyridin-2-yl)methanol (α-Pyr), (diphenylphosphoryl)(pyridin-3-yl)methanol (β-Pyr), and (diphenylphosphoryl)(pyridin-4-yl)methanol (γ-Pyr) were measured after immobilization onto colloidal gold surface. Changes in the wavenumber, broadness, and enhancement between the corresponding Raman and SERS bands allowed to deduce orientation of theα-,β-, andγ-isomers (α-,β-, andγ-refer to the position of the substituent relative to the ring nitrogen atom) of aminophosphonate derivatives of pyridine on the gold surface. Briefly, it was demonstrated that theα-Pyr andβ-Pyr show the same mode of adsorption, whereas the adsorption process of theγ-Pyr isomer differs in this regard that pyridine assists in the interaction with the gold surface.

Synthesis and Structure of a Novel Silver(I) Perchlorate 2,2′:6′,2″-Terpyridine Adduct Solvated With Acetonitrile

1994 ◽  
Vol 47 (8) ◽  
pp. 1545 ◽  
Author(s):  
S Binsilong ◽  
JD Kildea ◽  
WC Patalinghug ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Room Temperature ◽  
Silver Atom ◽  
The Other ◽  
Acetonitrile Solution ◽  
Central Ring ◽  
X Ray ◽  
Golden Yellow ◽  
Crystalline Adduct ◽  
Ring Nitrogen ◽  
Silver Atoms

Recrystallization of an equimolar mixture of silver(I) perchlorate and 2,2′:6′,2″-terpyridine ( terpy ) from acetonitrile solution yields the golden yellow crystalline adduct shown by a room-temperature single-crystal X-ray study to be [Ag3( terpy )4][( MeCN )Ag( terpy )](ClO4)4. Crystals are triclinic, Pī , a 21.48(1), b 14.525(7), c 13.506(8) Ǻ, α 68.50(4), β 80.71(4), γ 81.66(4)°, Z 2 formula units; R was 0.045 for 9681 'observed' reflections. The complex helical cation is quasi- centrosymmetric with a collinear Ag3 array. The environment of the central silver atom is planar four-coordinate, two short Ag-N distances [(2.198(5), 2.188(5)Ǻ] arising from the nitrogen atoms of outer rings of a pair of twisted terpy ligands ; the other two sites are occupied by the nitrogen atoms of the central terpy rings which bifurcate to the other silver atoms [Ag(central)-N(central) 2.624(5), 2.818(5)Ǻ; Ag(outer)-N(central) 2.704(4), 2.640(4)Ǻ], which are also coordinated by the outer ring nitrogen of the two ligands [Ag-N, 2.266(5), 2.304(4) Ǻ]. Coplanar with the latter, each outer silver atom has a further tridentate terpy coordinated [Ag-N(central) 2.362(4), 2.381(4)Ǻ; Ag-N(outer) 2.403(6)-2.573(5)Ǻ]. The [( MeCN )Ag( terpy )]+ species is also quasi-planar, Ag- NCMe being 2.174(7)Ǻ, opposed to the central ring nitrogen [2.331(5)Ǻ; Ag-N(outer) being 2.399(7), 2.433(7)Ǻ].

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