bluuebunny/crossref_metadata_2025_split huggingface dataset:
HIV‐1‐infected and/or immune activated macrophages regulate astrocyte SDF‐1 production through IL‐1β
Authors: Peng Hui , Erdmann Nathan , Whitney Nicholas , Dou Huangyu , Gorantla Santhi , Gendelman Howard E. , Ghorpade Anuja , Zheng Jialin 
Published: August 2006

AbstractStromal cell‐derived factor 1 alpha (SDF‐1α) and its receptor CXCR4 play important roles in the pathogenesis of human immunodeficiency virus type one (HIV‐1)‐associated dementia (HAD) by serving as a HIV‐1 co‐receptor and affecting cell migration, virus‐mediated neurotoxicity, and neurodegeneration. However, the underlying mechanisms regulating SDF‐1 production during disease are not completely understood. In this report we investigated the role of HIV‐1 infected and immune competent macrophage, the principal target cell and mediator of neuronal injury and death in HAD, in regulating SDF‐1 production by astrocytes. Our data demonstrated that astrocytes are the primary cell type expressing SDF‐1 in the brain. Immune‐activated or HIV‐1‐infected human monocyte‐derived‐macrophage (MDM) conditioned media (MCM) induced a substantial increase in SDF‐1 production by human astrocytes. This SDF‐1 production was directly dependent on MDM IL‐1β following both viral and immune activation. The MCM‐induced production of SDF‐1 was prevented by IL‐1β receptor antagonist (IL‐1Ra) and IL‐1β siRNA treatment of human MDM. These laboratory observations were confirmed in severe combined immunodeficient (SCID) mice with HIV‐1 encephalitis (HIVE). In these HIVE mice, reactive astrocytes showed a significant increase in SDF‐1 expression, as observed by immunocytochemical staining. Similarly, SDF‐1 mRNA levels were increased in the encephalitic region as measured by real time RT‐PCR, and correlated with IL‐1β mRNA expression. These observations provide direct evidence that IL‐1β, produced from HIV‐1‐infected and/or immune competent macrophage, induces production of SDF‐1 by astrocytes, and as such contribute to ongoing SDF‐1 mediated CNS regulation during HAD. © 2006 Wiley‐Liss, Inc.
Schwann cell‐derived neuregulin‐2α can function as a cell‐attached activator of muscle acetylcholine receptor expression
Authors: Ponomareva Olga N. , Fischer Tobias M. , Lai Cary , Rimer Mendell 
Published: August 2006

AbstractHere we show that neuregulin‐2 (Nrg‐2) α‐ and β‐isoforms can activate acetylcholine receptor (AChR) transcription as surface‐attached ligands. More importantly, we demonstrate that Schwann cells that express Nrg‐2α on their cell surface, the same Nrg‐2 isoform expressed by terminal Schwann cells at the neuromuscular junction, can induce AChR expression if brought into cell‐to‐cell contact with myotubes specifically expressing ErbB4. These Schwann cells, the D6P2T cell line, induce AChR expression apparently as well as 293T cells transfected with Nrg‐2β, the isoform with the highest AChR‐inducing activity when presented in a soluble form. These results provide a potential role for the previously reported, paradoxical perisynaptic accumulation of Nrg‐2α, the isoform with the least AChR‐inducing activity when presented in a soluble form. They also raise the possibility that Schwann cell‐derived Nrg‐2 could activate ErbB receptors on the synaptic sarcolemma and that this could account, at least in part, for the Nrg‐mediated regulation of AChR expression. © 2006 Wiley‐Liss, Inc.
Frontoparietal cortical activity of methamphetamine‐dependent and comparison subjects performing a delay discounting task
Authors: Monterosso John R. , Ainslie George , Xu Jiansong , Cordova Xochitl , Domier Catherine P. , London Edythe D. 
Published: August 2006

AbstractRelative to individuals who do not have addictive disorders, drug abusers exhibit greater devaluation of rewards as a function of their delay (“delay discounting”). The present study sought to extend this finding to methamphetamine (MA) abusers and to help understand its neural basis. MA abusers (n = 12) and control subjects who did not use illicit drugs (n = 17) participated in tests of delay discounting with hypothetical money rewards. We then used a derived estimate of each individual's delay discounting to generate a functional magnetic resonance imaging probe task consisting of three conditions: “hard choices,” requiring selections between “smaller, sooner” and “larger, later” alternatives that were similarly valued given the individual's delay discounting; “easy choices,” in which alternatives differed dramatically in value; and a “no choice” control condition. MA abusers exhibited more delay discounting than control subjects (P < 0.05). Across groups, the “hard choice > no choice” contrast revealed significant effects in the ventrolateral prefrontal cortex, dorsolateral prefrontal cortex (DLPFC), dorsal anterior cingulate cortex, and areas surrounding the intraparietal sulcus (IPS). With group comparisons limited to these clusters, the “hard choice > easy choice” contrast indicated significant group differences in task‐related activity within the left DLPFC and right IPS; qualitatively similar nonsignificant effects were present in the other clusters tested. Whereas control subjects showed less recruitment associated with easy than with hard choices, MA abusers generally did not. Correlational analysis did not indicate a relationship between this anomaly in frontoparietal recruitment and greater degree of delay discounting exhibited by MA abusers. Therefore, while apparent inefficiency of cortical processing related to decision‐making in MA abusers may contribute to the neural basis of enhanced delay discounting by this population, other factors remain to be identified. Hum. Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Spatiotemporal cortical dynamics underlying abstract and concrete word reading
Authors: Dhond Rupali P. , Witzel Thomas , Dale Anders M. , Halgren Eric 
Published: August 2006

AbstractThe current study used whole‐head anatomically constrained magnetoencephalography (aMEG) to spatiotemporally map brain responses while subjects made abstract/concrete judgments on visually presented words. Both word types evoked a similar posterior‐to‐anterior sequence of cortical recruitment involving occipital, temporal, parietal, and frontal areas from ∼ 100 to 900 ms poststimulus. A prominent left temporofrontal N400m was smaller to abstract words, while the right temporal N400m was smaller to concrete words, suggesting that differences may exist in their semantic representation. The left temporofrontal decrease for abstract words is consistent with EEG studies, indicating a smaller N400 for abstract words based on a more extensive or accessible lexicosemantic network. Furthermore, the N400m peaked at ∼420 ms and was followed by a large right hemisphere medial occipitoparietal as well as lateral parietal response to concrete words peaking at ∼550 ms, perhaps embodying imagistic processing. These data suggest that words may be initially understood using a left‐lateralized (frontotemporal) verbal‐linguistic system that for concrete words is supplemented after a short delay by a right parietal and medial occipital imagistic network. Hum Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Functional neural circuits for mental timekeeping
Authors: Stevens Michael C. , Kiehl Kent A. , Pearlson Godfrey , Calhoun Vince D. 
Published: August 2006

AbstractTheories of mental timekeeping suggest frontostriatal networks may mediate performance of tasks requiring precise timing. We assessed whether frontostriatal networks are functionally integrated during the performance of timing tasks. Functional magnetic resonance imaging (fMRI) data from 31 healthy adults were collected during performance of several different types of discrete interval timing tasks. Independent component analysis (ICA) was used to examine functional connectivity within frontostriatal circuits. ICA identifies groups of spatially discrete brain regions sharing similar patterns of hemodynamic signal change over time. The results confirm the existence of a frontostriatal neural timing circuit that includes anterior cingulate gyrus, supplementary motor area, bilateral anterior insula, bilateral putamen/globus pallidus, bilateral thalamus, and right superior temporal gyrus and supramarginal gyrus. Several other distinct neural circuits were identified that may represent the neurobiological substrates of different information processing stages of mental timekeeping. Small areas of right cerebellum were engaged in several of these circuits, suggesting that cerebellar function may be important in, but not the primary substrate of, the mental timing tasks used in this experiment. These findings are discussed within the context of current biological and information processing models of neural timekeeping. Hum. Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Comparison of the neural basis for imagined writing and drawing
Authors: Harrington Greg S. , Farias Dana , Davis Christine H. , Buonocore Michael H. 
Published: August 2006

AbstractDrawing and writing are complex processes that require the synchronization of cognition, language, and perceptual‐motor skills. Drawing and writing have both been utilized in the treatment of aphasia to improve communication. Recent research suggests that the act of drawing an object facilitated naming, whereas writing the word diminished accurate naming in individuals with aphasia. However, the relationship between object drawing and subsequent phonological output is unclear. Although the right hemisphere is characteristically mute, there is evidence from split‐brain research that the right hemisphere can integrate pictures and words, likely via a semantic network. We hypothesized that drawing activates right hemispheric and left perilesional regions that are spared in aphasic individuals and may contribute to semantic activation that supports naming. Eleven right‐handed subjects participated in a functional MRI (fMRI) experiment involving imagined drawing and writing and 6 of the 11 subjects participated in a second fMRI experiment involving actual writing and drawing. Drawing and writing produced very similar group activation maps including activation bilaterally in the premotor, inferior frontal, posterior inferior temporal, and parietal areas. The comparison of drawing vs. writing revealed significant differences between the conditions in areas of the brain known for language processing. The direct comparison between drawing and writing revealed greater right hemisphere activation for drawing in language areas such as Brodmann area (BA) 46 and BA 37. Hum. Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Indeterminate acute liver failure: A riddle wrapped in a mystery inside an enigma
Authors: Davern Timothy J. 
Published: August 2006

Abstract

Fulminant hepatitis of unknown origin remains a significant cause of mortality, for which liver transplantation is often considered as the only therapeutic option. In retrospective studies, human herpesvirus 6 (HHV-6) infections have been associated with such diseases, but the diagnosis of HHV-6 infection of the liver is rarely established during the acute phase of liver failure. Using real-time polymerase chain reaction (PCR), we diagnosed two cases of severe acute liver failure (ALF) related to HHV-6 occurring in immunocompetent young adults. Both cases had a favourable outcome, one after valganciclovir therapy and one after liver transplantation associated with ganciclovir. Viral origin was evidenced in each case by the detection of high amounts of HHV-6 DNA in liver tissue by the PCR assay. The decrease of intrahepatic viral load after therapeutic intervention was also monitored by quantitative PCR and paralleled in the two cases the clinical improvement. Diagnosis of HHV-6 infection must be systematically evoked in case of unexplained ALF, since it might lead to specific therapeutic interventions, in addition to liver transplantation.
Methylene‐Bridged Metallocenes with 2,2′‐Methylenebis[1H‐inden‐1‐yl] Ligands: Synthesis, Characterization, and Polymerization Catalysis of a Synthetically Simple Class of C2‐ and C2v‐Symmetric ansa‐Metallocenes
Authors: Resconi Luigi , Camurati Isabella , Fiori Cristina , Balboni Davide , Mercandelli Pierluigi , Sironi Angelo 
Published: August 2006

AbstractThe acid‐catalyzed reaction between formaldehyde and 1H‐indene, 3‐alkyl‐ and 3‐aryl‐1H‐indenes, and six‐membered‐ring substituted 1H‐indenes, with the 1H‐indene/CH2O ratio of 2 : 1, at temperatures above 60° in hydrocarbon solvents, yields 2,2′‐methylenebis[1H‐indenes] 1–8 in 50–100% yield. These 2,2′‐methylenebis[1H‐indenes] are easily deprotonated by 2 equiv. of BuLi or MeLi to yield the corresponding dilithium salts, which are efficiently converted into ansa‐metallocenes of Zr and Hf. The unsubstituted dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[1H‐inden‐1‐yl]}zirconium ([ZrCl2(1′)]) is the least soluble in organic solvents. Substitution of the 1H‐indenyl moieties by hydrocarbyl substituents increases the hydrocarbon solubility of the complexes, and the presence of a substituent larger than a Me group at the 1,1′ positions of the ligand imparts a high diastereoselectivity to the metallation step, since only the racemic isomers are obtained. Methylene‐bridged ‘ansa‐zirconocenes’ show a noticeable open arrangement of the bis[1H‐inden‐1‐yl] moiety, as measured by the angle between the planes defined by the two π‐ligands (the ‘bite angle’). In particular, of the ‘zirconocenes’ structurally characterized so far, the dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[4,7‐dimethyl‐1H‐inden‐1‐yl]}zirconium ([ZrCl2(5′)] is the most open. The mixture [ZrCl2(1′)]/methylalumoxane (MAO) is inactive in the polymerization of both ethylene and propylene, while the metallocenes with substituted indenyl ligands polymerize propylene to atactic polypropylene of a molecular mass that depends on the size of the alkyl or aryl groups at the 1,1′ positions of the ligand. Ethene is polymerized by rac‐dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[1‐methyl‐1H‐inden‐1‐yl]}zirconium ([ZrCl2(2′)])/MAO to polyethylene waxes (average degree of polymerization ca. 100), which are terminated almost exclusively by ethenyl end groups. Polyethylene with a high molecular mass could be obtained by increasing the size of the 1‐alkyl substituent.
Synthesis, Interionic Structure, and Reactivity toward CO and p‐Methylstyrene of Palladacyclic Compounds Bearing α‐Diimine Ligands
Authors: Zuccaccia Cristiano , Bellachioma Gianfranco , Cardaci Giuseppe , Macchioni Alceo , Binotti Barbara , Carfagna Carla 
Published: August 2006

AbstractPalladacyclic compounds [Pd(C6H4(C6H5CO)CNR)(NN)] [X] (R = Et, iPr, 2,6‐iPr2C6H3; NN = bpy = 2,2′‐bipyridine, or 1,4‐(o,o′‐dialkylaryl)‐1,4‐diazabuta‐1,3‐dienes; [X]− = [BF4]− or [PF6]−) were synthesized from the dimers [{Pd(C6H4(C6H5CO)CNR)(μ‐Cl)}2] and NN ligands. Their interionic structure in CD2Cl2 was determined by means of 19F,1H‐HOESY experiments and compared with that in the solid state derived from X‐ray single‐crystal studies. [Pd(C6H4(C6H5CO)CNR)(NN)] [X] complexes were found to copolymerize CO and p‐methylstyrene affording syndiotactic or isotactic copolymers when bpy or 1,4‐(o,o′‐dimethylaryl)‐1,4‐diazabuta‐1,3‐dienes were used, respectively. The reactions with CO and p‐methylstyrene of the bpy derivatives were investigated. Two intermediates derived from a single and a double insertion of CO into the PdC bonds were isolated and completely characterized in solution.
Chiral (Diphosphonite)platinum Complexes in Asymmetric Hydroformylation
Authors: van Duren Ruben , Cornelissen Leandra L. J. M. , van der Vlugt Jarl Ivar , Huijbers Jeroen P. J. , Mills Allison M. , Spek Anthony L. , Müller Christian , Vogt Dieter 
Published: August 2006

AbstractThe chiral diphosphonite ligand (11bR,11′bR)‐4,4′‐(9,9‐dimethyl‐9H‐xanthene‐4,5‐diyl)bis[dinaphtho[2,1‐d:1′,2′‐f][1,3,2]dioxaphosphepin] ((R,R)‐XantBino; (R)‐1), based on a rigid xanthene backbone, was applied in the Pt/Sn‐catalyzed hydroformylation of styrene (4a), 4‐methylstyrene (4b), vinyl acetate (4c), and allyl acetate (4d), by using a Pt/Sn ratio of 1 : 1. High ee of up to 80% were observed, along with good regioselectivities towards the desired branched aldehydes. For styrene, an interesting inversion in the stereoselection process was observed at elevated temperatures, and a mechanism is proposed considering the temperature dependence of the regioselectivity. The complex [PtCl2{(S,S)‐XantBino}] ((S)‐2) was characterized by X‐ray crystal‐structure analysis, revealing an unusual out‐of‐plane ligand coordination of the metal fragment. The complex [PtCl(SnCl3){(R,R)‐XantBino}] ((R)‐3) was characterized by means of 31P‐NMR spectroscopy.
Copolymerization of 7‐Methylenebicyclo[4.1.0]heptane with Carbon Monoxide Initiated by Optically Active Palladium Complexes
Authors: Takeuchi Daisuke , Yasuda Ayami , Okada Takeshi , Kuwabara Junpei , Osakada Kohtaro , Tomooka Katsuhiko 
Published: August 2006

AbstractSeven Pd‐complexes with optically active bis[dihydroxazole]‐type ligands promote asymmetric alternating copolymerization of 7‐methylenebicyclo[4.1.0]heptane with CO, which produces an optically active polyketone, [C(CH2)COC6H10]n. The reaction under increased CO pressure (> 5 atm) affords a polymer that contains monomer units with the cis‐cyclohexane‐1,2‐diyl group almost exclusively. The polyketone exhibits positive or negative optical rotation depending on the Pd‐complex. The highest and lowest [α]$\rm{_{{D}}^{25} }$ of the polymer obtained are + 68.9 and − 76.1, respectively. Addition of dibutylcuprate to a solution of the polymer in the presence of Me3SiCl transforms the enone groups of the polymer to silyl enol ether groups, which are ozonized to (silyloxy)oxirane moieties.
Systematic Study of the Asymmetric Methoxycarbonylation of Styrene Catalyzed by Palladium Systems Containing Chiral Ferrocenyl Diphosphine Ligands
Authors: Godard Cyril , Ruiz Aurora , Claver Carmen 
Published: August 2006

AbstractWe present the first systematic study of the Pd‐catalyzed asymmetric methoxycarbonylation of styrene in the presence of chiral ferrocenyl phosphine ligands. The reaction conditions were optimized, and a screening of different catalyst precursors was performed. A number of 1,1′‐bis(phosphino)ferrocenes of theMandyphos, Josiphos, Walphos, andTaniaphostypes were tested in combination with [PdCl2(NCPh)2], in the presence of TsOH as the acid source. These systems afforded high enantioselectivities, although the regioselectivity of the reaction was found to be in favor of the (undesired) linear ester. The catalytic system made with theJosiphosligand1gave rise to an enantiomeric excess (ee) of 86%.
Preparation of Partially Hydrogenated 4,6‐Dimethyldibenzothiophenes
Authors: Kukula Pavel , Gramlich Volker , Prins Roel 
Published: August 2006

AbstractThe synthesis of three key intermediates of the hydrogenation pathway in the hydrodesulfurization of 4,6‐dimethyldibenzothiophene (4,6‐DM‐DBT; 1) is described. The hydrogenated derivatives 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene (= 4,6‐dimethyl‐1,2,3,4‐tetrahydrodibenzothiophene; 4,6‐DM‐TH‐DBT; 2), 1,2,3,4,4a,9b‐hexahydro‐4,6‐dimethyldibenzothiophene (= 4,6‐dimethyl‐1,2,3,4,4a,9b‐hexahydrodibenzothiophene; 4,6‐DM‐HH‐DBT; 3), and dodecahydro‐4,6‐dimethyldibenzothiophene (= 4,6‐dimethylperhydrodibenzothiophene; 4,6‐DM‐PH‐DBT; 4) were prepared by direct hydrogenation of 1. The reactions were carried out in continuous and batch reactors by using metal sulfide as well as noble‐metal catalysts. The influence of the reaction conditions on the formation of the products and the distribution of their stereoisomers was studied in detail. The isomers of the main products were isolated and characterized by NMR, GC/MS/MS, and X‐ray crystal‐structure diffractometry.
Asymmetric Hydroformylation of Vinylfurans Catalyzed by {(11bS)‐4‐{[(1R)‐2′‐Phosphino[1,1′‐binaphthalen]‐2‐yl]oxy}dinaphtho[2,1‐d:1′,2′‐f]‐ [1,3,2]dioxaphosphepin}rhodium(I) [RhI{(R,S)‐binaphos}] Derivatives
Authors: Nakano Koji , Tanaka Ryo , Nozaki Kyoko 
Published: August 2006

AbstractThe asymmetric hydroformylation of 2‐ and 3‐vinylfurans (2a and 2b, resp.) was investigated by using [Rh{(R,S)‐binaphos}] complexes as catalysts ((R,S)‐binaphos = (11bS)‐4‐{[1R)‐2′‐phosphino[1,1′‐binaphthalen]‐2‐yl]oxy}dinaphtho[2,1‐d:1′,2′‐f][1,3,2]dioxaphosphepin; 1). Hydroformylation of 2 gave isoaldehydes 3 in high regio‐ and enantioselectivities (Scheme 2 and Table). Reduction of the aldehydes 3 with NaBH4 successfully afforded the corresponding alcohols 5 without loss of enantiomeric purity (Scheme 3).
Cobalt‐Catalyzed Carbonylation of N‐Alkylbenzaldimines to ‘N‐Alkylphthalimidines’ (= 2,3‐Dihydro‐1H‐isoindol‐1‐ones) via Tandem CH Activation and Cyclocarbonylation
Authors: Funk Jeffrey K. , Yennawar Hemant , Sen Ayusman 
Published: August 2006

AbstractThe reaction of N‐alkylbenzaldimines with carbon monoxide (CO) in the presence of cobalt (Co) catalysts resulted in the formation of N‐alkylphthalimidines (Table 1). Their formation is proposed to occur by CH activation of the aryl ring, migratory insertion of the hydride species into the benzaldimine functionality, CO coordination, and insertion into the CoC bond, followed by reductive elimination of the N‐alkylphthalimidine and regeneration of the starting Co species (Scheme 4). Deuterium (2H)‐labeling NMR studies are consistent with this mechanism (Scheme 5).
Chloro(η6‐p‐cymene)(phosphoramidite)ruthenium(II), a 16‐Electron Fragment Stabilized by an η2‐Aryl–Metal Interaction, and Its Use in Asymmetric Cyclopropanation
Authors: Huber Dominik , Kumar P. G. Anil , Pregosin Paul S. , Mikhel Igor S. , Mezzetti Antonio 
Published: August 2006

AbstractChloride abstraction from the half‐sandwich complexes [RuCl2(η6‐p‐cymene)(P*‐κP)] (2a: P* = (Sa,R,R)‐1a = (1Sa)‐[1,1′‐binaphthalene]‐2,2′‐diyl bis[(1R)‐1‐phenylethyl)]phosphoramidite; 2b: P* = (Sa,R,R)‐1b = (1Sa)‐[1,1′‐binaphthalene]‐2,2′‐diyl bis[(1R)‐(1‐(1‐naphthalen‐1‐yl)ethyl]phosphoramidite) with (Et3O)[PF6] or Tl[PF6] gives the cationic, 18‐electron complexes dichloro(η6‐p‐cymene){(1Sa)‐[1,1′‐binaphthalene]‐2,2′‐diyl {(1R)‐1‐[(1,2‐η)‐phenyl]ethyl}[(1R)‐1‐phenylethyl]phosphoramidite‐κP}ruthenium(II) hexafluorophosphate (3a) and [Ru(S)]‐dichloro(η6‐p‐cymene){(1Sa)‐[1,1′‐binaphthalene]‐2,2′‐diyl {(1R)‐1‐[(1,2‐η)‐naphthalen‐1‐yl]ethyl}[(1R)‐1‐(naphthalen‐1‐yl)ethyl]phosphoramidite‐κP)ruthenium(II) hexafluorophosphate (3b), which feature the η2‐coordination of one aryl substituent of the phosphoramidite ligand, as indicated by 1H‐, 13C‐, and 31P‐NMR spectroscopy and confirmed by an X‐ray study of 3b. Additionally, the dissociation of p‐cymene from 2a and 3a gives dichloro{(1Sa)‐[1,1′‐binaphthalene]‐2,2′‐diyl [(1R)‐(1‐(η6‐phenyl)ethyl][(1R)‐1‐phenylethyl]phosphoramidite‐κP)ruthenium(II) (4a) and di‐μ‐chlorobis{(1Sa)‐[1,1′‐binaphthalene]‐2,2′‐diyl [(1R)‐1‐(η6‐phenyl)ethyl][(1R)‐1‐phenylethyl]phosphoramidite‐κP}diruthenium(II) bis(hexafluorophosphate) (5a), respectively, in which one phenyl group of the N‐substituents is η6‐coordinated to the Ru‐center. Complexes 3a and 3b catalyze the asymmetric cyclopropanation of α‐methylstyrene with ethyl diazoacetate with up to 86 and 87% ee for the cis‐ and the trans‐isomers, respectively.
Ligand‐Controlled Formation of a Low‐Valent Pincer Rhodium(I)–Dioxygen Adduct Bearing a Very Short OO Bond
Authors: Frech Christian M. , Shimon Linda J. W. , Milstein David 
Published: August 2006

AbstractTreatment of [{Me2C6H(CH2PtBu2)2}Rh(η1‐N2)] (1a) with molecular oxygen (O2) resulted in almost quantitative formation of the dioxygen adduct [{Me2C6H(CH2PtBu2)2}Rh(η2‐O2)] (2a). An X‐ray diffraction study of 2a revealed the shortest OO bond reported for RhO2 complexes, indicating the formation of a RhIO2 adduct, rather than a cyclic RhIII η2‐peroxo complex. The coordination of the O2 ligand in 2a was shown to be reversible. Treatment of 2a with CO gas yielded almost quantitatively the corresponding carbonyl complex [{Me2C6H(CH2PtBu2)2}Rh(CO)] (3a). Surprisingly, treatment of the structurally very similar pincer complex [{C6H3(CH2PiPr2)2)}Rh(η1‐N2)] (1b) with O2 led to partial decomposition, with no dioxygen adduct being observed.