bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and Conformational Aspects of Equatorial and Axial Trifluoromethyl, Difluoromethyl, and Monofluoromethyl Groups
Authors: Huchet Quentin A. , Schweizer W. Bernd , Kuhn Bernd , Carreira Erick M. , Müller Klaus 
Published: October 2016

AbstractThe X‐ray crystal structures of cis‐ and trans‐1‐(indol‐3‐yl)‐4‐methyl cyclohexane and its congeners with stepwise fluorination of the methyl group are reported. The trans‐configured compounds adopted diequatorial conformations, whereas the cis analogues adopted regular cyclohexane chair conformations with the methyl group preferentially assuming the axial position, even in the case of the CF3 group. Surprisingly, although the axial CF3 derivative displayed distinct valence deformations in the cyclohexane moiety, the observed structural changes were relatively modest. The cis derivatives with axial mono‐ and difluorinated methyl groups exhibited conformational disorder in the crystals with significant population levels for the staggered conformations that had one fluorine atom in the endo position; their respective trans counterparts adopted unique conformations, but again with one fluorine atom in the endo position. Theoretical calculations for a series of cis‐ and trans‐1,4‐dimethyl cyclohexane model compounds with stepwise fluorination of one equatorial or axial methyl group reproduced the experimentally observed structural response patterns very well, reproduced the experimentally determined nonlinear correlation of the axial–equatorial energy difference with the degree of methyl fluorination in a satisfactory manner, and provided further insights into important conformational aspects of partially fluorinated methyl groups.
The Relationship between NMR Chemical Shifts of Thermally Polarized and Hyperpolarized 89Y Complexes and Their Solution Structures
Authors: Xing Yixun , Jindal Ashish K. , Regueiro‐Figueroa Martín , Le Fur Mariane , Kervarec Nelly , Zhao Piyu , Kovacs Zoltan , Valencia Laura , Pérez‐Lourido Paulo , Tripier Raphaël , Esteban‐Gómez David , Platas‐Iglesias Carlos , Sherry A. Dean 
Published: October 2016

AbstractRecently developed dynamic nuclear polarization (DNP) technology offers the potential of increasing the NMR sensitivity of even rare nuclei for biological imaging applications. Hyperpolarized 89Y is an ideal candidate because of its narrow NMR linewidth, favorable spin quantum number (I=
), and long longitudinal relaxation times (T1). Strong NMR signals were detected in hyperpolarized 89Y samples of a variety of yttrium complexes. A dataset of 89Y NMR data composed of 23 complexes with polyaminocarboxylate ligands was obtained using hyperpolarized 89Y measurements or 1H,89Y‐HMQC spectroscopy. These data were used to derive an empirical equation that describes the correlation between the 89Y chemical shift and the chemical structure of the complexes. This empirical correlation serves as a guide for the design of 89Y sensors. Relativistic (DKH2) DFT calculations were found to predict the experimental 89Y chemical shifts to a rather good accuracy.
Product Control using Substrate Design: Ruthenium‐Catalysed Oxidative C−H Olefinations of Cyclic Weinreb Amides
Authors: Das Riki , Kapur Manmohan 
Published: October 2016

AbstractA new class of Weinreb amides has been developed as directing groups for the ruthenium‐catalysed regioselective oxidative C−H olefination. The new Weinreb amides successfully inhibit the N−O bond reductive cleavage usually associated with the cationic ruthenium system, thereby keeping intact the synthetic utility of Weinreb amides. Mechanistic studies reveal interesting aspects of the directing group capabilities of Weinreb amides when compared to simple amides of similar structures.
A Porphyrin‐Based Porous rtl Metal–Organic Framework as an Efficient Catalyst for the Cycloaddition of CO2 to Epoxides
Authors: Jiang Wei , Yang Jin , Liu Ying‐Ying , Song Shu‐Yan , Ma Jian‐Fang 
Published: October 2016

AbstractA porous rtl metal–organic framework (MOF) [Mn5L(H2O)6⋅(DMA)2]⋅5DMA⋅4C2H5OH (1⋅Mn) (H10L=5,10,15,20‐tetra(4‐(3,5‐dicarboxylphenoxy)phenyl)porphyrin; DMA=N,N′‐dimethylacetamide) was synthesized by employing a new porphyrin‐based octacarboxylic acid ligand. 1⋅Mn exhibits high MnII density in the porous framework, providing it great Lewis‐acid heterogeneous catalytic capability for the cycloaddition of CO2 with epoxides. Strikingly, 1⋅Mn features excellent catalytic activity to the cycloaddition of CO2 to epoxides, with a remarkable initial turnover frequency 400 per mole of catalyst per hour at 20 atm. As‐synthesized 1⋅Mn also exhibits size selectivity to different epoxide substrates on account of their steric hindrance. The high catalytic activity, size selectivity, and stability toward the epoxides on catalytic cycloaddition of CO2 make 1⋅Mn a promising heterogeneous catalyst for fixation and utilization of CO2.
[FeFe]‐Hydrogenase H‐Cluster Mimics with Unique Planar μ‐(SCH2)2ER2 Linkers (E=Ge and Sn)
Authors: Abul‐Futouh Hassan , Almazahreh Laith R. , Sakamoto Takahiro , Stessman Nhu Y. T. , Lichtenberger Dennis L. , Glass Richard S. , Görls Helmar , El‐Khateeb Mohammad , Schollhammer Philippe , Mloston Grzegorz , Weigand Wolfgang 
Published: October 2016

AbstractAnalogues of the [2Fe‐2S] subcluster of hydrogenase enzymes in which the central group of the three‐atom chain linker between the sulfur atoms is replaced by GeR2 and SnR2 groups are studied. The six‐membered FeSCECS rings in these complexes (E=Ge or Sn) adopt an unusual conformation with nearly co‐planar SCECS atoms perpendicular to the Fe‐Fe core. Computational modelling traces this result to the steric interaction of the Me groups with the axial carbonyls of the Fe2(CO)6 cluster and low torsional strain for GeMe2 and SnMe2 moieties owing to the long C−Ge and C−Sn bonds. Gas‐phase photoelectron spectroscopy of these complexes shows a shift of ionization potentials to lower energies with substantial sulfur orbital character and, as supported by the computations, an increase in sulfur character in the predominantly metal–metal bonding HOMO. Cyclic voltammetry reveals that the complexes follow an ECE‐type reduction mechanism (E=electron transfer and C=chemical process) in the absence of acid and catalysis of proton reduction in the presence of acid. Two cyclic tetranuclear complexes featuring the sulfur atoms of two Fe2S2(CO)6 cores bridged by CH2SnR2CH2, R=Me, Ph, linkers were also obtained and characterized.
Systematic Modulation of the Fluorescence Brightness in Boron‐Dipyrromethene (BODIPY)‐Tagged N‐Heterocyclic Carbene (NHC)–Gold–Thiolates
Authors: Halter Oliver , Vasiuta Roman , Fernández Israel , Plenio Herbert 
Published: October 2016

AbstractFive different highly fluorescent boron‐dipyrromethene (BODIPY)‐tagged N‐heterocyclic carbene NHC–gold halide complexes were synthesized. The substitution of the halogeno ligand by 4‐substituted aryl thiolates leads to a decrease in the brightness of the complexes. This decrease depends on the electronic nature of the thiols, being most pronounced with highly electron‐rich thiols (4‐R=NMe2). The brightness of the gold thiolates also depends on the distance between the sulfur atom and the BODIPY moiety. The systematic variation of the electron density of [(NHC–bodipy)Au(SC6H4R)] (via different R groups) enables the systematic variation of the fluorescence brightness of an appended BODIPY fluorophore. Based on this and supported by DFT calculations, a photoinduced electron‐transfer quenching appears to be the dominant mechanism controlling the brightness of the appended BODIPY dye.
Two‐State Reactivity of Histone Demethylases Containing Jumonji‐C Active Sites: Different Mechanisms for Different Methylation Degrees
Authors: Alberro Nerea , Torrent‐Sucarrat Miquel , Arrastia Iosune , Arrieta Ana , Cossío Fernando P. 
Published: October 2016

AbstractThe N‐demethylation reactions of N,N,N‐trimethylpropan‐1‐ammonium and N,N‐dimethyl‐ and N‐methylpropan‐1‐aminium cations in the presence of [(AcO)2(imidazole)2(H2O)Fe=O] complex have been studied by density functional theory. These transformations are suitable models for the N‐demethylation of tri‐, di‐, and monomethylated lysine residues of histones in the presence of Jumonji‐C containing histone demethylases. It has been found that the N‐demethylation reaction is stepwise and occurs on triplet and quintet potential energy hypersurfaces. Both spin states are nearly degenerated and the quantum jump from one state to another has a transition probability close to one. The preferred intrinsic mechanism depends upon the methylation degree. For trimethylated residues the mechanism consists of a proton abstraction from a methyl group followed by a formation of a hydroxymethylaminium intermediate. This mechanism also occurs when dimethylated residues are able to orientate one methyl group towards the Fe=O group of the catalytic site. In contrast, when a N−H group of the substrate is close enough to the Fe=O group, the intrinsically preferred N‐demethylation reaction leads to the formation of an iminium intermediate that can be hydrolyzed to form the corresponding N‐demethylated product.
A Systematic Account on Aromatic Hydroxylation by a Cytochrome P450 Model Compound I: A Low‐Pressure Mass Spectrometry and Computational Study
Authors: Cantú Reinhard Fabián G. , Sainna Mala A. , Upadhyay Pranav , Balan G. Alex , Kumar Devesh , Fornarini Simonetta , Crestoni Maria Elisa , de Visser Sam P. 
Published: October 2016

AbstractCytochrome P450 enzymes are heme‐containing mono‐oxygenases that mainly react through oxygen‐atom transfer. Specific features of substrate and oxidant that determine the reaction rate constant for oxygen atom transfer are still poorly understood and therefore, we did a systematic gas‐phase study on reactions by iron(IV)‐oxo porphyrin cation radical structures with arenes. We present herein the first results obtained by using Fourier transform‐ion cyclotron resonance mass spectrometry and provide rate constants and product distributions for the assayed reactions. Product distributions and kinetic isotope effect studies implicate a rate‐determining aromatic hydroxylation reaction that correlates with the ionization energy of the substrate and no evidence of aliphatic hydroxylation products is observed. To further understand the details of the reaction mechanism, a computational study on a model complex was performed. These studies confirm the experimental hypothesis of dominant aromatic over aliphatic hydroxylation and show that the lack of an axial ligand affects the aliphatic pathways. Moreover, a two‐parabola valence bond model is used to rationalize the rate constant and identify key properties of the oxidant and substrate that drive the reaction. In particular, the work shows that aromatic hydroxylation rates correlate with the ionization energy of the substrate as well as with the electron affinity of the oxidant.
Chemical Non‐Innocence of an Aliphatic PNP Pincer Ligand
Authors: Schneck Felix , Finger Markus , Tromp Moniek , Schneider Sven 
Published: October 2016

AbstractThe synthesis of the divinylamido PNP nickel(II) complex [NiBr{N(CHCHPtBu2)2}] is reported. This compound exhibits reversible, ligand‐centered oxidation and protonation reactions. The resulting pincer chemical non‐innocence can be utilized for benzylic C−H hydrogen atom abstraction. The thermochemistry and kinetics of hydrogen atom transfer were examined.
Ru‐Catalyzed Dehydrogenative C−O Bond Formation with Anilines and Phenols
Authors: Heitz Christophe , Jones Alexander W. , Oezkaya Bünyamin S. , Bub Christina L. , Louillat‐Habermeyer Marie‐Laure , Wagner Victoria , Patureau Frederic W. 
Published: October 2016

AbstractThe Ru catalyzed cross‐dehydrogenative C−O bond formation between anilines and phenols is described and discussed. The exclusive C−O versus C−N bond‐formation selectivity, moreover in the absence of chelating–assisting directing groups and while leaving the N−H position untouched, is a remarkable feature of this metal‐catalyzed radical cross‐dehydrogenative coupling.
ChemInform Abstract: Li2GeMo3O8: A Novel Reduced Molybdenum Oxide Containing Mo3O13 Cluster Units.
Authors: Gall Philippe , Gougeon Patrick 
Published: October 2016

AbstractSingle crystals of the title compound are prepared by solid state reaction of a stoichiometric mixture of Li2MoO4, GeO2, MoO3, and Mo (arc‐welded Mo crucible under reduced Ar pressure, 1923 K, 72 h).
ChemInform Abstract: Two New Lanthanide Members of Francisite Family Cu3Ln(SeO3)2O2Cl (Ln: Eu, Lu).
Authors: Zakharov K. V. , Zvereva E. A. , Kuznetsova E. S. , Berdonosov P. S. , Dolgikh V. A. , Markina M. M. , Olenev A. V. , Shakin A. A. , Volkova O. S. , Vasiliev A. N. 
Published: October 2016

AbstractPolycrystalline Cu3Eu(SeO3)2O2Cl and Cu3Lu(SeO3)2O2Cl are prepared by solid state reaction of Eu2O3 (Lu2O3), CuO, CuCl2, and SeO2 (evacuated quartz tubes, 1.
ChemInform Abstract: Fluorine‐Doped Antiperovskite Electrolyte for All‐Solid‐State Lithium‐Ion Batteries.
Authors: Goodenough John B. 
Published: October 2016

AbstractLi2(OH)0.9F0.1Cl is prepared by melting mixtures of Li2O, LiOH, and LiX (X: Cl, F) at 350 °C for 0.5—1 h.
ChemInform Abstract: The Application of N‐Protected 3‐Vinylindoles in Chiral Phosphoric Acid‐Catalyzed [3 + 2] Cyclization with 3‐Indolylmethanols: Monoactivation of the Catalyst to Vinyliminium.
Authors: Fan Tao , Zhang Hong‐Hao , Li Can , Shen Yang , Shi Feng 
Published: October 2016

AbstractThe enantioselective [3 + 2] cycloaddition of isatin‐derived 3‐indolylmethanols with 3‐vinylindoles is optimized with respect to the BINOL‐type phosphonic acid catalyst and the reaction solvent.
ChemInform Abstract: MOF‐253‐Pd(OAc)2: A Recyclable MOF for Transition‐Metal Catalysis in Water.
Authors: Van Zeeland Ryan , Li Xinle , Huang Wenyu , Stanley Levi M. 
Published: October 2016

AbstractThe new reusable catalyst is utilized in conjugate addition reactions of arylboronic acids to β,β‐disubstituted enones in aqueous media.
ChemInform Abstract: Enantio‐ and Diastereoselective Desymmetrization of α‐Alkyl‐α‐diazoesters by Dirhodium(II)‐Catalyzed Intramolecular C—H Insertion.
Authors: Miyazawa Taku , Minami Kazushi , Ito Motoki , Anada Masahiro , Matsunaga Shigeki , Hashimoto Shunichi 
Published: October 2016

AbstractThe title reaction proceeds best in the presence of the Rh catalyst shown to form bicyclic ring systems with at least one cyclopentane unit in an enantio‐ and diastereoselective manner.
ChemInform Abstract: Dipeptide‐Derived Multifunctional Phosphonium Salt as a Catalyst to Synthesize Highly Functionalized Chiral Cyclopentanes.
Authors: Lu Yingpeng , Cao Dongdong , Zhang Jiaxing , Wang Hongyu , Zou Gang , Zhao Gang 
Published: October 2016

AbstractThe reaction affords cyclopentane structures with 3 contiguous stereocenters and a quaternary carbon atom.
ChemInform Abstract: Preparation of Enantiomerically Enriched Aromatic β‐Hydroxynitriles and Halohydrins by Ketone Reduction with Recombinant Ketoreductase KRED1‐Pglu.
Authors: Contente Martina L. , Serra Immacolata , Molinari Francesco , Gandolfi Raffaella , Pinto Andrea , Romano Diego 
Published: October 2016

AbstractVarious types of ketone substrates can be efficiently reduced in the presence of the title enzyme, isolated from P.
ChemInform Abstract: A New Synthetic Strategy to 2,3‐Diallyl‐1,4‐quinones via One‐Pot Double Claisen Rearrangement and Retro Diels—Alder Reaction.
Authors: Kotha Sambasivarao , Gunta Rama 
Published: October 2016

AbstractA simple alternative method to 2,3‐diallyl‐1,4‐quinone derivatives via a one‐pot double claisen rearrangement and retro Diels—Alder reaction sequence involving readily available starting materials is reported.
ChemInform Abstract: One‐Pot Three Component Synthesis of 3,5‐Disubstituted 2,6‐Dicyanoaniline Derivatives Using 4‐Dimethylaminopyridine (DMAP) as a Catalyst.
Authors: Bhattacharjee Suchandra , Khan Abu T. 
Published: October 2016

AbstractAn improved methodology for the construction of densely substituted benzene, from a wide variety of aldehydes, malononitrile, and β‐nitro‐olefins by using a nucleophilic catalyst DMAP is designed.
ChemInform Abstract: Heterogeneous Copper‐Catalyzed Aerobic Oxidative Conversions of Benzaldehydes with Aqueous Ammonia to Give Benzonitriles.
Authors: Yoon Yousun , Kim Bo Ram , Lee Chang Yeon , Kim Jinho 
Published: October 2016

AbstractPyrolysis of copper(II) 1,3,5‐benzenetricarboxylate provides a heterogeneous copper catalyst, which is successfully employed for the synthesis of benzonitriles from benzaldehydes.
ChemInform Abstract: Switchable [3 + 2] and [4 + 2] Heteroannulation of Primary Propargylamines with Isonitriles to Imidazoles and 1,6‐Dihydropyrimidines: Catalyst Loading Enabled Reaction Divergence.
Authors: Tong Shuo , Wang Qian , Wang Mei‐Xiang , Zhu Jieping 
Published: October 2016

AbstractA simple switch in the catalyst loading under otherwise identical conditions allows the preparation of either the pyrazole or dihydropyrimidine skeleton, represented by polysubstituted derivatives.
ChemInform Abstract: Asymmetric Synthesis of Pyrano[2,3‐c]pyrazoles via a Cascade Reaction Between Morita—Baylis—Hillman Acetates of Nitroalkenes and Pyrazolones.
Authors: Xie Jin , Sha Feng , Wu Xin‐Yan 
Published: October 2016

AbstractOptimized conditions A) allow the preparation of the pharmaceutically important scaffold with excellent enantio‐ and diastereoselectivity.
ChemInform Abstract: Transition Metal Free Intramolecular Approach for the Synthesis of Cyclopenta[b]chromene Derivatives from Phenol Substituted Fulvene Derived Azabicyclic Olefins.
Authors: Vijayan Ajesh , Baiju T. V. , Varughese Sunil , Radhakrishnan K. V. 
Published: October 2016

AbstractA versatile route for the synthesis of cyclopentene fused chromenes via base catalyzed transformation of phenol substituted fulvene derived azabicyclic olefins is described.
ChemInform Abstract: Metal‐Free Synthesis of Highly Substituted Quinolines under Mild Conditions.
Authors: Natarajan Rakesh , Unnikrishnan Peruparambil A. , Radhamani Sandhya , Rappai John P. , Prathapan Sreedharan 
Published: October 2016

AbstractStarting from easily accessible nitrones and acetylenes, a simple, metal free synthesis of substituted quinolines under mild conditions with high atom efficiency is developed.
ChemInform Abstract: Rapid and Efficient Cascade Synthesis of 2‐Amino‐4(3H)‐quinazolinones over an in situ‐Generated Heterogeneous CuCO3—K2CO3 Nanocomposite.
Authors: Thakur Maheshwar S. , Nayal Onkar S. , Bhatt Vinod , Sharma Sushila , Kumar Neeraj 
Published: October 2016

AbstractThe nanocomposite catalyzed cascade reaction of 2‐halobenzoic acids and guanidines or amidines proceeds rapidly in air without the addition of a ligand or additive to form quinazoline derivatives.
ChemInform Abstract: Copper‐Catalyzed C—H Oxygenation of Benzoxepine‐4‐carboxylates: Facile Synthesis and Photophysical Properties of Naphtho[2,1‐d]oxazoles and Benzo[c]phenoxazines.
Authors: Prasad Kasagani Veera , Saidachary Gannerla , Hariprasad Kurma Siva , Nagaraju Peethani , Rao Vaidya Jayathirtha , Raju Bhimapaka China 
Published: October 2016

AbstractA solvent‐free one‐pot protocol is developed for the reaction of oxepine derivatives (I) with anilines and benzylamine to afford benzophenoxazines and naphthooxazoles.
ChemInform Abstract: Synthesis of Pyrrolo[2,1‐f][1,2,4]triazin‐4(3H)‐ones: Rearrangement of Pyrrolo[1,2‐d][1,3,4]oxadiazines and Regioselective Intramolecular Cyclization of 1,2‐Biscarbamoyl‐substituted 1H‐Pyrroles.
Authors: Son Kkonnip , Park Seong Jun 
Published: October 2016

AbstractRegioselective intramolecular cyclization of pyrrole substrates (I) provide pyrrolooxadiazines (II) which undergo rearrangement to form pyrrolotriazines (III).
ChemInform Abstract: Dynamic Kinetic Resolution Approach for the Asymmetric Synthesis of Tetrahydrobenzodiazepines Using Transfer Hydrogenation by Chiral Phosphoric Acid.
Authors: Horiguchi Kosaku , Yamamoto Eri , Saito Kodai , Yamanaka Masahiro , Akiyama Takahiko 
Published: October 2016

AbstractDihydrobenzodiazepines or benzodiazepines bearing aryl substituents at the 2‐ and 4‐position of the heterocyclic part are transformed to the chiral title compounds in the presence of BNPA using different amounts of the hydrogen transfer reagent BTA.
ChemInform Abstract: Total Synthesis of (.+‐.)‐Lingzhilactone B via Semipinacol Rearrangement.
Authors: Chen Dong , Li Xiao‐Mei , Liu Hao‐Miao , Li Ming‐Ming , Cheng Yong‐Xian , Qin Hong‐Bo 
Published: October 2016

AbstractThe first total synthesis of the title compound (I) is described.
ChemInform Abstract: A New Method of Synthesis and Characterization of Nano‐Sized Mercuric Iodide by Solid‐Gas Reaction.
Authors: Agrawal Namita Rani , Fredrick Shobna Dorthy , Das Ishwar 
Published: October 2016

AbstractNanocrystalline HgI2 (7—52 nm) is prepared by solid gas reaction of Hg2(NO3)2 and I2 vapor either in glass capillaries, on microslides, or in a specifically designed glass channel (35 °C).
ChemInform Abstract: A Concise Enantioselective Synthesis of (+)‐L‐733,060 and (+)‐T‐2328 via Sequential Proline Catalysis.
Authors: Lalwani Komal G. , Sudalai Arumugam 
Published: October 2016

Abstract(+)‐L‐733,060 (I) is obtained by an asymmetric synthesis in 6 steps with an overall yield of 32% (93% e.e.) and (+)‐T‐2328 (II) in 10 steps with 28% overall yield (93% e.e.).
Effect of gravity orientation in the study of thermodiffusion
Authors: Mousavi Seyyed Arash , Yousefi Tooraj , Saghir Ziad 
Published: October 2016

AbstractThis paper describes the measurement of the Soret coefficient of a hydrocarbon binary liquid mixture at different orientations to the gravity vector. The working fluid in the experiment was composed of 1,2,3,4‐tetrahydronaphtalene (THN) and dodecane (C12) at mass fractions of 0.50/0.50 and a temperature of 298.15 K. The experimental technique used in this study was an optical digital interferometry method using a Mach‐Zehnder Interferometer. A fast Fourier transform method was used for image processing. The experimental approach was supplemented with a numerical solution using the finite volume method. Experimental and numerical results both confirmed that cell inclination during the thermodiffusion process had a tremendous effect on the measurement of the Soret coefficient.
Crystallization behaviour and lamellar thickness distribution of metallocene‐catalyzed polymer: Effect of 1‐alkene comonomer and branch length
Authors: Daud Muhammad , Shehzad Farrukh , Al‐Harthi Mamdouh A. 
Published: October 2016

AbstractThe effect of comonomer and branching on the melt crystallization and lamellar thickness distribution was studied for ethylene and 1‐alkene copolymers. The comonomers used in this study are 1‐hexene, 1‐octene, and 1‐decene. A notable influence of the comonomer ratio in the feed was observed on the crystallization and melting behaviour. The Ozawa and Mo models were found suitable for these copolymers. However, variation of relative crystallinity at different heating rates preferred the Mo method over the Ozawa method. The melting behaviour and lamellar thickness distribution of the copolymers were analyzed by the help of the modified Gibbs‐ Thomson equation. The activation energies (EA) for the melt crystallization were calculated using the Kissinger method. It was observed that 1‐hexene comonomer exhibits lower EA, indicating an easier crystallization process as compared to other comonomers used. Overall, crystallization was found to be more influenced by the degree of branching rather than the comonomer type.