bluuebunny/crossref_metadata_2025_split huggingface dataset:
The interaction of methyl chloride with a silicon(111) surface
Authors: Küster Regine , Christmann Klaus 
Published: July 2012

AbstractIn the technical Müller‐Rochow synthesis, dimethyl dichlorsilane (DMD) is fabricated from methyl chloride which interacts with a ‘contact mass’ consisting of elemental Si and Cu (Cu being a catalyst). In order to better understand some of the elementary steps of this reaction, we have followed the adsorption of methyl chloride on a (7×7) reconstructed Si(111) surface in the temperature range between 100 and 1000 K by means of LEED, Auger electron spectroscopy (AES), temperature‐programmed thermal desorption (TPD), vibrational loss spectroscopy (HREELS), and work function change (Δϕ) measurements. CH3C1 adsorbs effectively in a single weakly chemisorbed state. The adsorption energy is strongly coverage‐dependent and decreases from initially ˜ 40 kJ/mol to ˜ 30 kJ/mol near the monolayer. During adsorption, the work function of the Si(111) surface first increases sharply by 0.36 eV and saturates, after an intermediate maximum of ˜ 40 eV near the monolayer, at ˜ 0.61 eV. CH3C1‐derived vibrational losses appear at 88, 176, 340, and 370 meV and can be associated with known gas phase vibrations of CH3C1. An additional band at 260 meV is tentatively ascribed to the Si‐H stretching vibration, pointing to competing dissociation of adsorbed CH3C1 into hydrogen and methylene chloride CH2C1. Otherwise, CH3C1 does not react with Si(111) under our UHV conditions (CH3C1 partial pressures ≤10−5 mbar, 100 ≤T≤300 K), as the absence of any C1‐ and/or Si‐containing mass fragments in the TPD spectra proves. We deduce from our investigation that the combined chlorination and methylation of Si in the technical Müller‐Rochow process is dictated by processes which run only at much larger (atmospheric) pressures and/or elevated temperatures.
Molecular dynamics simulation of the proton transport in water
Authors: Schmidt Roger G. , Brickmann Jürgen 
Published: July 2012

AbstractThe proton transport in water is treated within a mixed molecular dynamic (MD) and Monte Carlo (MC) scheme. Therein the migration of a positive charge is treated as a two step process; (i) as a displacement of a hydronium ion and (ii) as a proton transfer between a hydronium ion and an adjacent water molecule. Both, the hydronium ion and the water molecules are treated as rigid molecules. It is found that the determining step for the proton transport rate is the dissociation rate of H5O2+complexes. In these complexes the O‐O distance is only 2.4–2.5 Å while the corresponding distance for two water molecules in solution is 2.83 Å. In the H5O2+complex the proton does no longer belong to a single water molecule, but is delocalized between the two oxygen atoms. This situation is modelled by an exchange of the water and the hydronium every time step with a probabilityp= 1/2.
Collisional deactivation of vibrationally highly excited benzyl radicals
Authors: Damm M. , Deckert F. , Hippler H. 
Published: July 2012

AbstractThe collisional deactivation of vibrationally highly excited benzyl radicals in the ground electronic state has been investigated. Vibrationally excited benzyl radicals have been generated using the fast dissociation of vibrationally excited ethylbenzene prepared from UV absorption followed by fast internal conversion. Subsequent to complete collisional deactivation the benzyl radicals have been reexcited by the absorption of a further UV‐photon also followed by fast internal conversion. Once again the collisional deactivation of the benzyl radicals has been monitored by time‐resolved UV absorption spectroscopy. Average energies transferred per collision have been determined by comparison of absorption‐time profiles with different initial vibrational energies. It was found that the rate of collisional deactivation of the open shell benzyl radical is almost identical to the rate of collisional deactivation of the closed shell hydrocarbons of similar size.
Engineering Strategies for Successful Development of Functional Polymers Using Oxidative Enzymes
Authors: Nyanhongo G. S. , Nugroho Prasetyo E. , Herrero Acero E. , Guebitz G. M. 
Published: July 2012

AbstractEnzyme application in polymer engineering is rapidly increasing and is set to revolutionize many industries. Given the multidisciplinary nature of this field, it has become clear that successful development of functional polymers entails tapping into advances in bioengineering, molecular biology, genetic engineering, chemical engineering, biochemistry, material science, nanotechnology, etc. This review summarizes the different strategies and reaction conditions that can influence the synthesis or modification of polymers. It is hoped that this review will provide scientists from different backgrounds with information on the different reaction engineering strategies for the successful development of functional polymers using oxidative enzymes.
Solid‐State NMR Investigations of Supported Ionic Liquid Phase Water‐Gas Shift Catalysts: Ionic Liquid Film Distribution vs. Catalyst Performance
Authors: Haumann M. , Schönweiz A. , Breitzke H. , Buntkowsky G. , Werner S. , Szesni N. 
Published: July 2012

AbstractThe ionic liquid film distribution in supported ionic liquid phase (SILP) catalysts has been studied by solid‐state NMR. [EMIM][NTf2] was immobilized onto silica gel 100 support with loadings between 0 and 40 vol.‐%. The 1H NMR signals indicated an exchange process between the support's surface silanol groups and the protons of the ionic liquid. At ionic liquid loadings below 10 vol.‐%, islands of ionic liquids seemed to form, whereas at higher loadings complete coverage of the support was achieved. The NMR‐based film model was confirmed by gas phase water‐gas shift experiments using known SILP catalysts with different ionic liquid loadings. At high ionic liquid loading, the activity of the catalyst decreased due to pore blocking. The NMR technique provided easy and reliable data for film formation and distribution and allows for optimization of SILP catalysts in the future.
Screening of Colloids by Semicontinuous Centrifugation
Authors: Spelter L. E. , Meyer K. , Nirschl H. 
Published: July 2012

AbstractThis work contributes to the field of solid‐liquid separation in focusing on the screening of colloidal particles in a semicontinuous process. The aim of the study is to provide the basics for a continuous classification process in industry. After a short introduction to the field of particle screening, a review of the possibilities of classification in the gas or liquid phase is presented, including analytical methods, devices for the fractionation on the laboratory scale as well as apparatus for screening on the pilot and industrial scale. The results show the dispersion, stabilization and classification of fine kaolin and polystyrene particles. Kaolin was used to demonstrate the possibility of removing the fraction of fine particles, polystyrene particles were used to investigate the removal of the coarse fraction. The diameter of the particles used in this study ranges from 250 nm to 3 μm.
Intramolecular Gas‐Phase Reactions of Synthetic Nonheme Oxoiron(IV) Ions: Proximity and Spin‐State Reactivity Rules
Authors: Mas‐Ballesté Rubén , McDonald Aidan R. , Reed Dana , Usharani Dandamudi , Schyman Patric , Milko Petr , Shaik Sason , Que Lawrence 
Published: July 2012

AbstractThe intramolecular gas‐phase reactivity of four oxoiron(IV) complexes supported by tetradentate N4 ligands (L) has been studied by means of tandem mass spectrometry measurements in which the gas‐phase ions [FeIV(O)(L)(OTf)]+ (OTf=trifluoromethanesulfonate) and [FeIV(O)(L)]2+ were isolated and then allowed to fragment by collision‐induced decay (CID). CID fragmentation of cations derived from oxoiron(IV) complexes of 1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane (tmc) and N,N′‐bis(2‐pyridylmethyl)‐1,5‐diazacyclooctane (L8Py2) afforded the same predominant products irrespective of whether they were hexacoordinate or pentacoordinate. These products resulted from the loss of water by dehydrogenation of ethylene or propylene linkers on the tetradentate ligand. In contrast, CID fragmentation of ions derived from oxoiron(IV) complexes of linear tetradentate ligands N,N′‐bis(2‐pyridylmethyl)‐1,2‐diaminoethane (bpmen) and N,N′‐bis(2‐pyridylmethyl)‐1,3‐diaminopropane (bpmpn) showed predominant oxidative N‐dealkylation for the hexacoordinate [FeIV(O)(L)(OTf)]+ cations and predominant dehydrogenation of the diaminoethane/propane backbone for the pentacoordinate [FeIV(O)(L)]2+ cations. DFT calculations on [FeIV(O)(bpmen)] ions showed that the experimentally observed preference for oxidative N‐dealkylation versus dehydrogenation of the diaminoethane linker for the hexa‐ and pentacoordinate ions, respectively, is dictated by the proximity of the target CH bond to the oxoiron(IV) moiety and the reactive spin state. Therefore, there must be a difference in ligand topology between the two ions. More importantly, despite the constraints on the geometries of the TS that prohibit the usual upright σ trajectory and prevent optimal σCH–σ* overlap, all the reactions still proceed preferentially on the quintet (S=2) state surface, which increases the number of exchange interactions in the d block of iron and leads thereby to exchange enhanced reactivity (EER). As such, EER is responsible for the dominance of the S=2 reactions for both hexa‐ and pentacoordinate complexes.
Application of a Structure/Oxidation‐State Correlation to Complexes of Bridging Azo Ligands
Authors: Das Amit , Scherer Thomas Michael , Mobin Shaikh M. , Kaim Wolfgang , Lahiri Goutam Kumar 
Published: July 2012

AbstractBased on data from more than 40 crystal structures of metal complexes with azo‐based bridging ligands (2,2′‐azobispyridine, 2,2′‐azobis(5‐chloropyrimidine), azodicarbonyl derivatives), a correlation between the NN bond lengths (dNN) and the oxidation state of the ligand (neutral, neutral/back‐donating, radical‐anionic, dianionic) was derived. This correlation was applied to the analysis of four ruthenium compounds of 2,2′‐azobispyridine (abpy), that is, the new asymmetrical rac‐[(acac)2Ru1(μ‐abpy)Ru2(bpy)2](ClO4)2 ([1](ClO4)2), [Ru(acac)2(abpy)] (2), [Ru(bpy)2(abpy)](ClO4)2 ([3](ClO4)2), and meso‐[(bpy)2Ru(μ‐abpy)Ru(bpy)2](ClO4)3 ([4](ClO4)3; acac−=2,4‐pentanedionato, bpy=2,2′‐bipyridine). In agreement with DFT calculations, both mononuclear species 2 and 32+ can be described as ruthenium(II) complexes of unreduced abpy0, with 1.295(5)<dNN<1.320(3) Å, thereby exhibiting effects from π back‐donation. However, the abpy ligand in both the asymmetrical diamagnetic compound 12+ (dNN=1.374(6) Å) and the symmetrical compound 43+ (dNN=1.360(7), 1.368(8) Å) must be formulated as abpy.−. Remarkably, the addition of [RuII(bpy)2]2+ to mononuclear [RuII(acac)2(abpy0)] induces intracomplex electron‐transfer under participation of the noninnocent abpy bridge to yield rac‐[(acac)2Ru1III(μ‐abpy.−)Ru2II(bpy)2]2+ (12+) with strong antiferromagnetic coupling between abpy.− and RuIII (DFT (B3LYP/LANL2DZ/6‐31G*)‐calculated triplet–singlet energy separation ES=1−ES=0=11739 cm−1). Stepwise one‐electron transfer was studied for compound 1n, n=1−, 0, 1+, 2+, 3+, by UV/Vis/NIR spectroelectrochemistry, EPR spectroscopy, and by DFT calculations. Whereas the first oxidation of compound 12+ was found to mainly involve the central ligand to produce an (abpy0)‐bridged Class I mixed‐valent Ru1IIIRu2II species, the first reduction of compound 12+ affected both the bridge and Ru1 atom to form a radical complex (1+), with considerable metal participation in the spin‐distribution. Further reduction moves the spin towards the {Ru2(bpy)2} entity.
Re‐examining the Mechanisms of Competing Pericyclic Reactions of 1,3,7‐Octatriene
Authors: Gutierrez Osvaldo , Harrison Jason G. , Pemberton Ryan P. , Tantillo Dean J. 
Published: July 2012

AbstractDFT (both B3LYP and M06‐2X), CASSCF, and CASPT2 calculations were used to investigate competing [3, 3] and [3, 5] sigmatropic shifts and intramolecular [4+2] cycloaddition of 1,3,7‐octatriene. In accord with previous results on 1,5‐hexadiene, CASSCF calculations found both stepwise and concerted pathways for the [3, 3] rearrangement. For the competing [3, 5] sigmatropic rearrangement, CASSCF and CASPT2 calculations revealed three stepwise pathways with similar barriers. UB3LYP and UM06‐2X calculations predicted a different potential energy landscape: no stepwise [3, 3] pathway, only two competing [3, 5] sigmatropic shifts, and an intramolecular Diels–Alder cycloaddition/homolytic ring‐opening pathway. Significant lowering of barriers for all rearrangements was predicted for some 1,3,7‐octatrienes with substituents at the 4‐ and 7‐positions.
ChemInform Abstract: The Polymorphism of CsThF5.
Authors: Underwood Christopher C. , Mann Matthew , McMillen Colin D. , Musgraves J. David , Kolis Joseph W. 
Published: July 2012

AbstractThree new polymorphs of CsThF5 are hydrothermally synthesized from ThF4 and aqueous CsF solutions of varying concentrations in a silver ampule (autoclave, 575 °C, 2—12 d).
ChemInform Abstract: Fast, Solvent‐Free and Hydrogen‐Bonding‐Mediated Asymmetric Michael Addition in a Ball Mill.
Authors: Wang Yi‐Feng , Chen Ru‐Xiang , Wang Ke , Zhang Bin‐Bin , Li Zhao‐Bo , Xu Dan‐Qian 
Published: July 2012

AbstractCinchona‐derived squaramide is an efficient catalyst for the asymmetric Michael addition of 1,3‐dicarbonyl compounds to nitroolefins under solvent‐free conditions.
ChemInform Abstract: Palladium‐Catalyzed Deamidative Arylation of Azoles with Arylamides Through a Tandem Decarbonylation—C—H Functionalization.
Authors: Li Chengliang , Li Pinhua , Yang Jin , Wang Lei 
Published: July 2012

AbstractThe highly chemo‐ and regioselective deamidative cross‐coupling of arylamides (II), as an aryl metal equivalent, with azoles (I), (IV), (VI) and (VIII) is described.
ChemInform Abstract: Magnetic Nanoparticles Catalyzed N‐tert‐Butoxycarbonylation of Amines and Amine Derivatives.
Authors: Akbari Jafar , Sajirani Soghra B. , Nezhad Jafar M. , Heydari Akbar 
Published: July 2012

AbstractMono N‐Boc protection of various amines succeeds chemoselectively in the presence of magnetically recoverable ferric oxide on silica nanoparticles.
ChemInform Abstract: A Copper‐Catalyzed Petasis Reaction for the Synthesis of Tertiary Amines and Amino Esters.
Authors: Frauenlob Robin , Garcia Carlos , Bradshaw Gary A. , Burke Helen M. , Bergin Enda 
Published: July 2012

AbstractIn the presence of CuBr/bipy, aldehydes bearing a coordinating group react smoothly with sterically unhindered amines and boronic acids.
ChemInform Abstract: Synthesis of Alcohols from m‐Fluorophenylsulfones and Dialkylboranes: Application to the C14—C35 Building Block of E7389.
Authors: Liu Lei , Henderson James A. , Yamamoto Akihiko , Bremond Paul , Kishi Yoshito 
Published: July 2012

AbstractThe method is applied to a broad spectrum of products including subunit (VIII).
ChemInform Abstract: Palladium‐Catalyzed C—N Cross‐Coupling of Sulfinamides and Aryl Halides.
Authors: Sun Xiaofei , Tu Xingzhao , Dai Chuan , Zhang Xiaoping , Zhang Binbin , Zeng Qingle 
Published: July 2012

AbstractOptimized conditions A) render possible the title reaction with aryl chlorides and bromides.
ChemInform Abstract: Consecutive Michael—Claisen Process for Cyclohexane‐1,3‐dione Derivative (CDD) Synthesis from Unsubstituted and Substituted Acetone.
Authors: Sharma Dharminder , Bandna Bandna , Shil Arun K. , Singh Bikram , Das Pralay 
Published: July 2012

AbstractRegioselective Michael reaction of ketones with alkyl acrylate derivatives is followed by Claisen cyclization to produce substituted cyclohexane‐1,3‐diones.
ChemInform Abstract: Microwave‐Assisted Copper‐Catalyzed Cross‐Coupling Reaction of Alkynes with Aryl Iodides and Vinyl Halides.
Authors: Tsai Wen‐Ting , Lin Yun‐Yung , Wang Yu‐Jen , Lee Chin‐Fa 
Published: July 2012

AbstractIn the presence of 2‐5 mol% CuI(Xantphos), the process is highly efficient for a broad spectrum of substrates bearing various functionalities.
ChemInform Abstract: Ligand‐Free Copper‐Catalyzed Coupling of Nitroarenes with Arylboronic Acids.
Authors: Zhang Jilei , Chen Jiuxi , Liu Miaochang , Zheng Xingwang , Ding Jinchang , Wu Huayue 
Published: July 2012

AbstractA new protocol for the synthesis of diaryl ethers via an unprecedented Cu‐catalyzed coupling of nitroarenes with arylboronic acids is developed.
ChemInform Abstract: Asymmetric Catalytic Mannich‐Type Reaction of Hydrazones with Difluoroenoxysilanes Using Imidzaoline‐Anchored Phosphine Ligand—Zinc(II) Complexes.
Authors: Yuan Zhiliang , Mei Liangyong , Wei Yin , Shi Min , Kattamuri Padmanabha V. , McDowell Patrick , Li Guigen 
Published: July 2012

AbstractA novel catalytic system is successfully applied to the mild title reaction.
ChemInform Abstract: Stereoselective Synthesis of Hydroxy Stilbenoids and Styrenes by Atom‐Efficient Olefination with Thiophthalides.
Authors: Mitra Prithiba , Shome Brateen , De Saroj Ranjan , Sarkar Anindya , Mal Dipakranjan 
Published: July 2012

AbstractThe preparation of the title compounds is accomplished with high (E)‐stereoselectivity where only elemental sulfur is lost.
ChemInform Abstract: Concise Synthesis of Chiral 2(5H)‐Furanone Derivatives Possessing 1,2,3‐Triazole Moiety via One‐Pot Approach.
Authors: Tan Yue‐He , Li Jian‐Xiao , Xue Fu‐Ling , Qi Ji , Wang Zhao‐Yang 
Published: July 2012

AbstractThe target compounds can be synthesized via a four‐component one‐pot method, a three‐component one‐pot method or a sequential method.
ChemInform Abstract: Copper(I)‐Mediated Cascade Reactions: An Efficient Approach to the Synthesis of Functionalized Benzofuro[3,2‐d]pyrimidines.
Authors: Chao Bo , Lin Shijun , Ma Qingdong , Lu Dong , Hu Youhong 
Published: July 2012

AbstractThe process renders possible the access to various medicinally important heterocyclic scaffolds.
ChemInform Abstract: Copper‐Catalyzed C—H Oxidation/Cross‐Coupling of α‐Amino Carbonyl Compounds.
Authors: Wu Ji‐Cheng , Song Ren‐Jie , Wang Zhi‐Qiang , Huang Xiao‐Cheng , Xie Ye‐Xiang , Li Jin‐Heng 
Published: July 2012

AbstractA novel, mild, and selective method for the synthesis of the compounds (III), (V), (VI), (VIII), and (IX) is reported.
ChemInform Abstract: Highly Efficient Oxidation of 2‐Imidazoline‐5‐carboxylic Derivatives to Imidazole‐5‐carboxylic Derivatives by Dioxygen.
Authors: Huang Yue , Zu Xiaodong , Wu Fan , Xu Jinyi , Wu Xiaoming , Yao Hequan 
Published: July 2012

AbstractA clean, mild and environmental‐benign method for the oxidation of imidazolines by dioxygen (or air) as the sole oxidant is developed.
ChemInform Abstract: Palladium‐Catalyzed Cyclization Reactions of 2,3‐Allenyl Amines with Propargylic Carbonates.
Authors: Ye Juntao , Li Suhua , Ma Shengming 
Published: July 2012

AbstractThe method allows the preparation of various highly functionalized oxazole structures, which are of importance in synthetic and medicinal chemistry.
ChemInform Abstract: Design and Application of New Imidazolylsulfonate‐Based Benzyne Precursor: An Efficient Triflate Alternative.
Authors: Kovacs Szabolcs , Csincsi Adam I. , Nagy Tibor Zs. , Boros Sandor , Timari Geza , Novak Zoltan 
Published: July 2012

AbstractSulfonylimidazole‐based benzyne precursors are utilized in the reactions with azides to form benzotriazoles, with tosyl hydrazone to form indazoles, with β‐ketoesters to form acyl alkylation products or with furans or pyrroles to form bridged compounds.
ChemInform Abstract: DBU‐Catalyzed Expeditious and Facile Multicomponent Synthesis of N‐Arylquinolines under Microwave Irradiation.
Authors: Singh Satish Kumar , Singh Krishna Nand 
Published: July 2012

AbstractAn efficient one‐pot three‐component microwave‐assisted reaction of aromatic aldehydes, 3‐arylamino‐5,5‐dimethylcyclohex‐2‐enone, and active methylene compounds catalyzed by DBU leads to various N‐arylquinoline derivatives (IV) (23 examples).
ChemInform Abstract: Intramolecular Sila‐Matteson Rearrangement: A General Access to Silylated Heterocycles.
Authors: Francois Cyril , Boddaert Thomas , Durandetti Muriel , Querolle Olivier , Van Hijfte Luc , Meerpoel Lieven , Angibaud Patrick , Maddaluno Jacques 
Published: July 2012

AbstractHigher yields and chemoselectivities are observed when tBuLi is used as a lithiating agent.
ChemInform Abstract: Highly Efficient Synthesis of a Class of Novel Chiral‐Bridged Atropisomeric Monophosphine Ligands via Simple Desymmetrization and Their Applications in Asymmetric Suzuki—Miyaura Coupling Reaction.
Authors: Wang Shouliang , Li Jinjin , Miao Tingting , Wu Wenhao , Li Qing , Zhuang Yue , Zhou Zhongyuan , Qiu Liqin 
Published: July 2012

AbstractAmong various derivatives, ligand (I) is found to be the most efficient one to produce axially chiral organophosphorus compounds.
ChemInform Abstract: A Selective Intramolecular Transacylation of Taxoids Accompanying with the Oxetane Ring Opening.
Authors: Gao Feng , Yu Min , Chen Qiao‐Hong , Wang Feng‐Peng 
Published: July 2012

AbstractIntramolecular transacylation from C‐4 to C‐5 of taxoids in the presence of TiCl4 proceeds with concomitant oxetane D‐ring opening to give novel taxoid derivatives, as demonstrated for paclitaxel (I).
ChemInform Abstract: Aza‐Claisen Rearrangement of 2‐C‐Hydroxymethyl Glycals as a Versatile Strategy Towards Synthesis of Isofagomine and Related Biologically Important Azasugars.
Authors: Reddy Y. Suman , Kancharla Pavan K. , Roy Rashmi , Vankar Yashwant D. 
Published: July 2012

AbstractRearrangement of hydroxymethyl glycals (I) leads to glycosyl trichloroacetamidates (III) as a mixture of α‐ and β‐anomers which are versatile precursors for the synthesis of several biologically active azasugars such as isofagomine (IV).
ChemInform Abstract: Racemic and Diastereoselective Construction of Indole Alkaloids under Solvent‐ and Catalyst‐Free Microwave‐Assisted Pictet—Spengler Condensation
Authors: Jida Mouhamad , Soueidan Olivier‐Mohamad , Deprez Benoit , Laconde Guillaume , Deprez‐Poulain Rebecca 
Published: July 2012

Abstract18 examples
ChemInform Abstract: Chemical Constituents of Plants from the Genus Euonymus
Authors: Zhu Jia‐Xian , Qin Jiang‐Jiang , Chang Rui‐Jie , Zeng Qi , Cheng Xiang‐Rong , Zhang Fei , Jin Hui‐Zi , Zhang Wei‐Dong 
Published: July 2012

AbstractReview: 106 refs.
Computed diffusion contribution in the complex blood oxygenation‐level dependent fMRI signal
Authors: Chen Zikuan , Calhoun Vince D. 
Published: July 2012

AbstractDiffusion is a ubiquitous phenomenon in blood oxygenation‐level dependent (BOLD) functional magnetic resonance imaging (fMRI), but it cannot be completely separated out from BOLD signals experimentally or theoretically. Nevertheless, it is possible to numerically characterize the diffusion‐only contribution by Monte Carlo simulation and signal analysis. The simulation was carried out for a variety of parameter settings of cortical vasculature (vessel radii = [2, 16] micron) and field strength (B0 = [0.18, 12.9] T). A cortical voxel was simulated in a cube of size 320 × 320 × 320 micron3 filled with a random vascular network. Diffusion‐present and diffusion‐absent signals were calculated by intravoxel dephasing (via switching on and off the diffusion coefficients) for a range of echo times TE = [0, 60] ms. Given a pair of diffusion‐present and diffusion‐absent complex signals, the diffusion‐only contribution was calculated by two signal analysis models: multiplication and addition. Statistics were rendered through multiple random realizations for each vasculature setting. Simulations suggest that diffusion contributes to BOLD signal (for setting of vessel radius = 3 micron, B0 = 3 T, TE = 30 ms) by a signal amplitude decay rate change of 0.8 Hz (multiplication model) or by a signal amplitude change percentage of 5% (addition model). Overall, this contribution is maximal amid a large range of field strengths, diminishing toward low and high fields. © 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part A 40A: 128–145, 2012.