Experimental and Quantum Chemical Studies of 2-Phosphinylphenol Derivatives

Carbon-oxygen bonds ortho to a phosphoryl group in triarylphosphine oxides undergo cleavage when the oxides are either fused with potassium hydroxide or treated with potassium tert-butoxide in refluxing toluene, presumably through a nucleophilic addition-elimination mechanism. Thus, bis(2-hydroxyphenyl)phenylphosphine oxide is produced along with the expected 2-phenoxyphenyl(phenyl)phosphinic acid from 10-phenyl-10H-phenoxaphosphine 10-oxide. The latter starting material is also produced, together with bis(2-hydroxyphenyl)phenylphosphine oxide, when bis(2-methoxyphenyl)phenylphosphine oxide is fused with potassium hydroxide. Fusion of bis(2-methoxyphenyl)phenylphosphine oxide with sodium hydroxide, however, yields 2-hydroxyphenyl(phenyl)phosphinic acid. Ab initio quantum chemical studies confirm that the downfield ³¹P chemical shift that is observed in 2-phosphinylphenols is due to hydrogen bonding to the phosphoryl group.     

Hydrogen bonding in 2‐amino‐4,6‐dimethoxypyrimidine, 2‐benzylamino‐4,6‐bis(benzyloxy)pyrimidine and 2‐amino‐4,6‐bis(N‐pyrrolidino)pyrimidine: chains of fused rings and a centrosymmetric dimer

Molecules of 2‐amino‐4,6‐di­methoxy­pyrimidine, C₆H₉N₃O₂, (I), are linked by two N—H?N hydrogen bonds [H?N 2.23 and 2.50 Å, N?N 3.106 (2) and 3.261 (2) Å, and N—H?N 171 and 145°] into a chain of fused rings, where alternate rings are generated by centres of inversion and twofold rotation axes. Adjacent chains are linked by aromatic π–π‐stacking interactions to form a three‐dimensional framework. In 2‐­benzylamino‐4,6‐bis(benzyloxy)pyrimidine, C₂₅H₂₃N₃O₂, (II), the mol­ecules are linked into centrosymmetric R(8) dimers by paired N—H?N hydrogen bonds [H?N 2.13 Å, N?N 2.997 (2) Å and N—H?N 170°]. Molecules of 2‐amino‐4,6‐bis(N‐pyrrolidino)­pyrimidine, C₁₂H₁₉N₅, (III), are linked by two N—H?N hydrogen bonds [H?N 2.34 and 2.38 Å, N?N 3.186 (2) and 3.254 (2) Å, and N—H?N 163 and 170°] into a chain of fused rings similar to that in (I).     

15N NMR spectroscopy 24—chemical shifts and coupling constants of α-amino acid N-carboxyanhydrides and related heterocycles

The chemical shifts of amino acid N-carboxyanhydrides (NCAs) and cyclic or linear urethanes are less sensitive to solvent effects than those of amides and lactams. The values of the one-bond ¹⁵N? ¹H coupling constants depend on the solvent and are 5-8 Hz larger than those of ureas and amides. The ¹⁵N? ¹³C coupling constant of the N? CO group is also unusually high, while that of the N—CH group lies within the range known for N-acylated aliphatic amines. The one-bond ¹⁵N? ¹³C coupling constant was found to be insensitive to conformational changes.     

[1,3‐Bis(4‐nitrophenyl)triazenido](triphenylphosphine)gold(I)

In the title complex, [Au(C₁₂H₈N₅O₄)(C₁₈H₁₅P)], the coordination geometry about the Au^I ion is linear, with one deprotonated 1,3‐bis(4‐nitro­phenyl)­triazenide ion, [O₂NC₆H₄N=N–NC₆H₄NO₂]⁻, acting as a monodentate ligand (two‐electron donor), and one neutral tri­phenyl­phosphine mol­ecule completing the metal coordination. The triazenide ligand is almost planar (r.m.s. deviation = 0.0767 Å), with the largest interplanar angle being 11.6 (7)° between the phenyl ring of one of the terminal 4‐nitro­phenyl substituents and the plane defined by the N=N—N triad. The Au—N and Au—P distances are 2.108 (5) and 2.2524 (13) Å, respectively. Pairs of mol­ecules generated by centrosymmetry are associated into a supramolecular array via intermolecular C—H⋯O inter­actions, and N⋯C and N⋯O π–π interactions.     

Soluble polynorbornenes with pendant carbazole derivatives as host materials for highly efficient blue phosphorescent organic light‐emitting diodes

We report novel host polymers for a high‐efficiency polymer‐based solution‐processed phosphorescent organic light‐emitting diode with typical blue‐emitting dopant bis(4,6‐difluorophenylpyridinato‐N,C²)iridium(III) picolinate (FIrpic). The host polymers, soluble polynorbornenes with pendant carbazole derivatives, N‐phenyl‐9H‐carbazole ( P1 ), N‐biphenyl‐9H‐carbazole ( P2 ), and 9,9′‐(1,3‐phenylene)bis‐9H‐carbazole (mCP) ( P3 ) are efficiently synthesized by vinyl addition polymerization of norbornene monomers using Pd(II) catalyst in combination with 1‐octene chain transfer agent. The polymers exhibit high thermal stability with high decomposition (T_d5 > 410 °C) and glass transition temperatures (T_g ≈ 268 °C). The HOMO (ca. ?5.5 to ?5.7 eV) and LUMO (ca. ?2.0 to ?2.1 eV) levels with the high triplet energy of about 2.7–3.0 eV suggest that the polymers are suitable for a host material for blue emitters. Among the solution‐processed devices that were fabricated based on the emissive layers containing the P1 ? P3 host doped with various concentrations of FIrpic (7–13 wt %), the best device with P3 host exhibits power efficiency of 3.0 lm W^?1 and external quantum efficiency of 4.0% at a luminance of 1000 cd m^?2 that is outstanding among the polymeric rivals. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Conformational dynamics of bis(BF2)‐2,2′‐bidipyrrins revealed by through‐space 13C?19F and 19F?19F couplings

The conformation of [bis‐(N,N′‐difluoroboryl)]‐3,3′‐diethyl‐4,4′,8,8′,9,9′,10,10′‐octamethyl‐2,2′‐bidipyrrin (1) in solution was studied by analyzing the ¹³C? ¹⁹F and ¹⁹F? ¹⁹F through‐space spin–spin couplings. The ¹H and ¹³C NMR spectra were assigned on the basis of nuclear Overhauser effect spectroscopy (NOESY), heteronuclear single‐quantum correlation (HSQC), and heteronuclear multiple‐bond correlation (HMBC) experiments. The ¹⁹F spectrum of 1 was compared with that of 2‐ethyl‐1,3,5,6,7‐pentamethyl‐4,4‐difluoro‐4‐bor‐3a,4a‐diaza‐s‐indacen (2). The ¹⁹F? ¹⁹F through‐space spin? spin coupling in 1 was thus assigned and the coupling constant was obtained by simulating the coupling patterns. The obtained conformation of 1 was compared with those of the known complexes [bis‐(N,N′‐difluoroboryl)]‐3,3′,8,8′,9,9′‐hexaethyl‐4,4′,10,10′‐tetramethyl‐6,6′‐(4‐methylphenyl)‐2,2′‐bidipyrrin (3)and [bis‐(N,N′‐difluoroboryl)]‐9,9′‐diethyl‐4,4′,8,8′,10,10′‐hexamethyl‐3,3′‐bis(methoxycarbonylethyl)‐2,2′‐bidipyrrin (4). The conformational dynamics of 1, 3, and 4 was surveyed by observing the temperature dependence of the through‐space coupling constants between 253 and 333 K. The ¹³C? ¹⁹F and ¹⁹F? ¹⁹F through‐space spin–spin couplings thus confirm similar conformations of different BisBODIPYs in solution in contrast to earlier findings in the solid state. Copyright © 2009 John Wiley & Sons, Ltd.     

1,3‐Bis(ethylamino)‐2‐nitrobenzene, 1,3‐bis(n‐octylamino)‐2‐nitrobenzene and 4‐ethylamino‐2‐methyl‐1H‐benzimidazole

1,3‐Bis(ethylamino)‐2‐nitrobenzene, C₁₀H₁₅N₃O₂, (I), and 1,3‐bis(n‐octylamino)‐2‐nitrobenzene, C₂₂H₃₉N₃O₂, (II), are the first structurally characterized 1,3‐bis(n‐alkylamino)‐2‐nitrobenzenes. Both molecules are bisected though the nitro N atom and the 2‐C and 5‐C atoms of the ring by twofold rotation axes. Both display intramolecular N—H...O hydrogen bonds between the amine and nitro groups, but no intermolecular hydrogen bonding. The nearly planar molecules pack into flat layers ca 3.4 Å apart that interact by hydrophobic interactions involving the n‐alkyl groups rather than by π–π interactions between the rings. The intra‐ and intermolecular interactions in these molecules are of interest in understanding the physical properties of polymers made from them. Upon heating in the presence of anhydrous potassium carbonate in dimethylacetamide, (I) and (II) cyclize with formal loss of hydrogen peroxide to form substituted benzimidazoles. Thus, 4‐ethylamino‐2‐methyl‐1H‐benzimidazole, C₁₀H₁₃N₃, (III), was obtained from (I) under these reaction conditions. Compound (III) contains two independent molecules with no imposed internal symmetry. The molecules are linked into chains via N—H...N hydrogen bonds involving the imidazole rings, while the ethylamino groups do not participate in any hydrogen bonding. This is the first reported structure of a benzimidazole derivative with 4‐amino and 2‐alkyl substituents.     

Chelate von Chinolin-8-ol — Derivaten. XI. Eigenschaften und Struktur von Nickelchelaten alkyl-substituierter Chinolin-8-ole bzw. Chinolin-8-thiole

Reactions of 1,1,3,3-Tetrakis(dimethylamino)-1λ⁵,3λ⁵-diphosphete with N? H and P? H Acidic Compounds 1,1,3,3-Tetrakis(dimethylamino)-1λ⁵,3λ⁵-diphosphete, 1 , reacts with aniline to give by opening of the ring 2,2,4,4-tetrakis(dimethylamino)-1-phenyl-1,2λ⁵,4λ⁵-azadiphosphapenta-1,3-diene, 2 , with p-CN? C₆F₄? NH₂ the product is 1-(4-cyano-2,3,5,6-tetrafluorophenyl)-2,2,4,4-tetrakis(dimethylamino)-1,2λ⁵,4λ⁵-azadiphosphapenta-1,3-diene, 3 . t-Butylamine or diethylamine do not react with 1 . Mesitylphosphane opens the ring system 1 forming by reduction of one phosphorus atom {[bis(dimethylamino)phosphanyl]methylidene}bis(dimethylamino)methylphosphorane, 4 . The same product 4 is obtained by reaction with phenylphosphane. The reaction products 2–4 are characterized by their nmr, mass, and ir spectra. Their way of formation is discussed. In 4 a ⁵J(PH), in 3 a ⁷J(CF) long range coupling constant could be identified.     

13C NMR: The stereochemical dependence of 15N?13C coupling constants in pyrazoles

Geminal ¹⁵N? ¹³C coupling constants have been measured in a series of ¹⁵N-enriched 1?phenyl?3,5?dialkyl-substituted pyrazoles. The importance of the orientation of the nitrogen lone-pair in determining the magnitude of ²J(¹⁵N¹³C) values is reflected in the enhanced coupling observed for those carbon atoms lying close in space to the lone-pair electrons.     

Adducts of 1,1,1‐tris(4‐hydroxyphenyl)ethane with diamines: three‐dimensional hydrogen‐bonded frameworks formed with 1,6‐diaminohexane and 2,2′‐bipyridyl

The adduct 1,6‐di­amino­hexane–1,1,1‐tris(4‐hydroxy­phenyl)­ethane (1/2) is a salt {hexane‐1,6‐diyldiammonium–4‐[1,1‐bis(4‐hydroxyphenyl)ethyl]phenolate (1/2)}, C₆H₁₈N₂²⁺·2C₂₀H₁₇O₃^?, in which the cation lies across a centre of inversion in space group P. The anions are linked by two short O—H?O hydrogen bonds [H?O 1.74 and 1.76 Å, O?O 2.5702 (12) and 2.5855 (12) Å, and O—H?O 168 and 169°] into a chain containing two types of R(24) ring. Each cation is linked to four different anion chains by three N—H?O hydrogen bonds [H?O 1.76–2.06 Å, N?O 2.6749 (14)–2.9159 (14) Å and N—H?O 156–172°]. In the adduct 2,2′‐bipyridyl–1,1,1‐tris(4‐hydroxy­phenyl)­ethane (1/2), C₁₀H₈N₂·2C₂₀H₁₈O₃, the neutral di­amine lies across a centre of inversion in space group P2₁/n. The tris­(phenol) mol­ecules are linked by two O—H?O hydrogen bonds [H?O both 1.90 Å, O?O 2.7303 (14) and 2.7415 (15) Å, and O—H?O 173 and 176°] into sheets built from R(38) rings. Pairs of tris­(phenol) sheets are linked via the di­amine by means of a single O—H?N hydrogen bond [H?N 1.97 Å, O?N 2.7833 (16) Å and O—H?N 163°].     

New rac‐XP(O)(OC6H5)(NHC6H4‐p‐CH3) [X = N(CH3)(cyclo‐C6H11) and NH(C3H5)] and rac‐(C6H5CH2NH)P(O)(OC6H5)(NH‐cyclo‐C6H11) mixed‐amide phosphinates

The mixed‐amide phosphinates, rac‐phenyl (N‐methylcyclohexylamido)(p‐tolylamido)phosphinate, C₂₀H₂₇N₂O₂P, (I), and rac‐phenyl (allylamido)(p‐tolylamido)phosphinate, C₁₆H₁₉N₂O₂P, (II), were synthesized from the racemic phosphorus–chlorine compound (R,S)‐(Cl)P(O)(OC₆H₅)(NHC₆H₄‐p‐CH₃). Furthermore, the phosphorus–chlorine compound ClP(O)(OC₆H₅)(NH‐cyclo‐C₆H₁₁) was synthesized for the first time and used for the synthesis of rac‐phenyl (benzylamido)(cyclohexylamido)phosphinate, C₁₉H₂₅N₂O₂P, (III). The strategies for the synthesis of racemic mixed‐amide phosphinates are discussed. The P atom in each compound is in a distorted tetrahedral (N¹)P(=O)(O)(N²) environment. In (I) and (II), the p‐tolylamido substituent makes a longer P—N bond than those involving the N‐methylcyclohexylamido and allylamido substituents. In (III), the differences between the P—N bond lengths involving the cyclohexylamido and benzylamido substituents are not significant. In all three structures, the phosphoryl O atom takes part with the N—H unit in hydrogen‐bonding interactions, viz. an N—H...O=P hydrogen bond for (I) and (N—H)(N—H)...O=P hydrogen bonds for (II) and (III), building linear arrangements along [001] for (I) and along [010] for (III), and a ladder arrangement along [100] for (II).     

Effect of the orientation of substituents on the chemical shifts of 13C. IV—13C NMR spectra of N,N-diisopropylamides and -thioamides

N,N-diisopropylamides and -thioamides show hindered rotation around the N? CH bonds, and the presence of mixtures of conformational isomers can be demonstrated at temperatures below 273 K in solution. ¹H and ¹³C NMR spectra of these conformers are measured and assigned. The ¹³C data serve to study through-space effects on ¹³C chemical shifts, which strongly depend on the conformations of the isopropyl groups. For amides, a through-space shielding of the N-methine carbons is found to exist only for conformers in which the methine hydrogen atom is spatially close to the oxygen atom. Chemical shift differences between amides and thioamides can be rationalized in terms of through-bond and through-space contributions, and serve for a better understanding of the shift differences in N,N-dialkylamides and -thioamides.     

4‐Vinyl­benzyl analogs of adenine and uracil: reactive monomers for nucleobase polymeric resins

The crystal structures of 9‐(4‐vinyl­benzyl)­adenine, C₁₄H₁₃N₅, and 1‐(4‐vinyl­benzyl)­uracil, C₁₃H₁₂N₂O₂, are composed of zigzag ribbon‐like structures that are stabilized by conventional (N—H?N‐type) hydrogen bonds for the former and conventional (N—H?O‐type) and non‐conventional (C—H?O‐type) hydrogen bonds for the latter; the hydrogen‐bonding patterns are represented by graph‐sets R(9) and R(8), respectively. The adenine and uracil moieties in these alkyl­ated derivatives are planar and are inclined at angles of 84.44 (4) and 79.07 (7)°, respectively, with respect to the phenyl rings.     

Tetraarylester der μ-Imidodiphosphorsäure und ihre Thioderivate — Strukturuntersuchungen

Tetraarylesters of μ-Imido-Diphosphoric Acid and its Thio Derivatives — Structure Investigations New O,O′,O″,O?-tetratolyl- and ditolyl-diphenylesters of the μ-imido-diphosphoric acid and its mono and dithio derivatives were synthesized, compared with the corresponding tetraphenylesters and investigated by ¹H, ¹³C, and ³¹P NMR spectroscopy and X-ray crystal structure analysis. Structures of the O,O′,O″,O?-tetrakis-(2-methyl-phenyl)-μ-imidodiphosphate, 1b , as well as of the corresponding ortho-, meta- and para-tolylesters of the μ-imido-monothiodiphosphoric acid ( 2a , 2b , 2c ) were determined. All the compounds form dimers via N? H…?O hydrogen bonds in the crystal as well as in nonpolar solvents. The distances around the phosphorus atoms rise with decreasing electronegativity of the phosphorus substituents. Signs of the ²J_{P? N? P} coupling constants were determined by ¹³C{¹H, ³¹P} triple resonance experiments for some compounds. These constants become more negative owing to substitution of a phosphoryl by a thiophosphoryl group.     

Cyclopolymerization. XIX. Effect of N-substituents on cyclopolymerizability of N-allylmethacrylamides

The effect of bulky N-substitutents of N-t-butyl- and N-phenyl-N-allylmethacrylamides (BAMA and PAMA, respectively) on their cyclopolymerizability was investigated. BAMA yielded an almost completely cyclized polymer while the degree of cyclization of poly (PAMA) was about 95%. The latter value indicates that the effect of phenyl group is comparable with that of methyl group, since N-methyl-N-allylmethacrylamide was reported to give a polymer with a degree of cyclization of 93%. Structural investigation on telomerization products of BAMA and PAMA permitted the assignment of the repeating cyclic units of these polymers to that of a five-membered ring. This structural characteristic was also supported by the observation of five-membered cyclized radicals on ESR measurements of these monomers. Rotation around amide C? N bonds of these monomers and related compounds studied by ¹³C-NMR was found to be strongly dependent on N-substitutents. The mechanism of the cyclization was discussed in terms of the structure of the ring formed and rotation around amide C? N bonds of these monomers. The reactivity of the methacryloyl and allyl groups involved in these monomers were compared based on the information obtained by structural investigation of polymers and telomerization products and by ESR studies. © 1993 John Wiley & Sons, Inc.     

Hindered rotation of the dimethylamino and dimethylthioamide groups in two ortho substituted N,N-dimethylthiobenzamides

Hindered rotation in two o-substituted N,N-dimethylthiobenzamides was investigated by variable temperature ¹H NMR spectroscopy. For one compound, the enthalpies and entropies of activation for (i) thioamide group rotation around the Ar? C bond and (ii) dimethylamino group rotation around the C? N bond were obtained by full line shape analysis; a possible coupling between the two processes is discussed. A new simple method has also been applied to the analysis of dimethylamino exchange and results are in complete agreement with the full line shape analysis with somewhat better precision.     

Rare examples of base pairing via a protonated pyridine N atom in two salts of N2,N6‐bis(1,3‐dimethylimidazolin‐2‐ylidene)pyridine‐2,6‐diamine

The title compounds, namely 2,6‐bis[(1,3‐dimethylimidazolin‐2‐ylidene)amino]pyridinium perchlorate, C₁₅H₂₄N₇⁺·ClO₄⁻, (I), and bis{2,6‐bis[(1,3‐dimethylimidazolin‐2‐ylidene)amino]pyridinium} μ‐oxido‐bis[trichloridoiron(III)], (C₁₅H₂₄N₇)₂[Fe₂Cl₆O], (II), are structurally unusual examples of the organization of molecular units via base pairing. The cations in salts (I) and (II) are derived from the bisguanidine N²,N⁶‐bis(1,3‐dimethylimidazolin‐2‐ylidene)pyridine‐2,6‐diamine, which associates in centrosymmetric pairs via two N—H...N hydrogen‐bond interactions. N—H...N bridges are formed between the protonated pyridine N atom and one of the nonprotonated guanidine N atoms, with N...H distances of 2.01 (1)–2.10 (1) Å. Compound (I) contains two crystallographically independent cations and anions per asymmetric unit. One of the perchlorate anions is disordered, while the [Fe₂Cl₆O]²⁻ anion lies on an inversion centre.     

Conformational equilibrium and dynamic behavior of bis‐N‐triflyl substituted 3,8‐diazabicyclo[3.2.1]octane

Restricted rotation about the N–S partial double bonds in a bis‐N‐triflyl substituted 3,8‐diazabicyclo[3.2.1]octane derivative 1 has been frozen at low temperature (ΔG^≠ = 11.6 kcal mol^?1), and the existence of all four rotamers about the two N–S bonds, 3‐in,8‐in, 3‐in,8‐out, 3‐out,8‐in, and 3‐out,8‐out, respectively, proved experimentally by NMR spectroscopy and theoretically by DFT and MP2 calculations. Copyright © 2014 John Wiley & Sons, Ltd.     

The assignment of diastereotopic menthyl groups by two-dimensional NMR

The ¹³C and ¹H NMR spectra of (–)-bis[1R, 3 R, 4S]menthylphosphine (1) are assigned by two-dimensional double quantum NMR and ¹³C? ¹H shift correlation diagrams. The variable temperature spectra of 1 indicate hindered rotation about the P? C bonds.     

1‐Methyl‐4‐nitraminopyridinium nitrate and 4‐nitraminopyridinium methanesulfonate

In the title compounds, C₆H₈N₃O₂⁺·NO₃^? and C₅­H₆­N₃­O₂⁺·­CH₃SO₃^?, respectively, the cations are almost planar; the twist of the nitr­amino group about the C—N and N—N bonds does not exceed 10°. The deviations from coplanarity are accounted for by intermolecular N—H?O interactions. The coplanarity of the NHNO₂ group and the phenyl ring leads to the deformation of the nitr­amino group. The C—N—N angle and one C—C—N angle at the junction of the phenyl ring and the nitr­amino group are increased from 120° by ca 6°, whereas the other junction C—C—N angle is decreased by ca 5°. Within the nitro group, the O—N—O angle is increased by ca 5° and one O—N—N angle is decreased by ca 5°, whereas the other O—N—N angle remains almost unchanged. The cations are connected to the anions by relatively strong N—H?O hydrogen bonds [shortest H?O separations 1.77 (2)–1.81 (3) Å] and much weaker C—H?O hydrogen bonds [H?O separations 2.30 (2)–2.63 (3) Å].