A5000195518- Organometallic Complex Synthesis and Catalysis
- Synthesis and characterization of novel inorganic/organometallic compounds
- Coordination Chemistry and Organometallics
- Asymmetric Hydrogenation and Catalysis
- Organoboron and organosilicon chemistry
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Organometallic Compounds Synthesis and Characterization
- Synthetic Organic Chemistry Methods
- Inorganic Chemistry and Materials
- Climate variability and models
- Atmospheric Ozone and Climate
- Metal complexes synthesis and properties
- Organophosphorus compounds synthesis
- Atmospheric and Environmental Gas Dynamics
- Ferrocene Chemistry and Applications
- Fluorine in Organic Chemistry
- Magnetism in coordination complexes
- Asymmetric Synthesis and Catalysis
- Catalytic Cross-Coupling Reactions
- Fullerene Chemistry and Applications
- Crystal structures of chemical compounds
- Organic Chemistry Cycloaddition Reactions
- Steroid Chemistry and Biochemistry
- Silicone and Siloxane Chemistry
Cornell University
2018-2025
Hebrew University of Jerusalem
2020
UNSW Sydney
2020
Courant Institute of Mathematical Sciences
2020
New York University
2020
University of Cambridge
2014-2019
Laboratoire de Météorologie Dynamique
2018-2019
École Polytechnique
2018-2019
Climate and Global Dynamics Laboratory
2018
NSF National Center for Atmospheric Research
2016-2018
Two new soft X-ray scanning transmission microscopes located at the Advanced Light Source (ALS) have been designed, built and commissioned. Interferometer control implemented in both allows precise measurement of transverse position zone plate relative to sample. Long-term positional stability compensation for displacement during translations achieved. The interferometer also provides low-distortion orthogonal x, y imaging. different systems developed: a digital system using standard VXI...
Crystals of 1,2 dilauroyl-DL-phosphatidyl-ethanolamine:acetic acid are monoclinic with a = 46.2, b 7.77, c 9.95 Å, β 92.0°; space group P 2 1 /c. The structural analysis, based on the visual estimates 1467 reflection intensities, was achieved by direct methods, and least squares analysis convergence to R 0.28. There marked differences between observed molecular conformation those that have been predicted theoretically. mean planes containing lipid chains essentially parallel one another;...
Abstract The coupling between the stratosphere and troposphere following two major stratospheric sudden warmings is studied in Canadian Middle Atmosphere Model using a nudging technique by which zonal-mean evolution of reference are artificially induced an ~100-member ensemble spun off from control simulation. Both taken freely running integration model. One event displacement, other split, both followed extended recoveries lower stratosphere. methodology permits statistically robust study...
Abstract The stratosphere can have a significant impact on winter surface weather subseasonal to seasonal (S2S) timescales. This study evaluates the ability of current operational S2S prediction systems capture two important links between and troposphere: (1) changes in probabilistic skill extratropical by precursors tropics troposphere (2) predictability extratropics after stratospheric weak strong vortex events. Probabilistic exists for events when including tropospheric over North Pacific...
Major sudden stratospheric warmings ( SSWs ) are striking phenomena of wintertime circulation usually defined as a reversal zonal mean from westerlies to easterlies. often have significant impact on tropospheric and cause anomalies in surface climate lasting for up 2 months. For this reason, dynamics predictability SSW receive considerable attention. It is however well‐known that not all significant, long‐lasting the troposphere. In order explain differences impacts following , several...
Abstract The stratosphere has been identified as an important source of predictability for a range processes on subseasonal to seasonal (S2S) time scales. Knowledge about S2S within the is however still limited. This study evaluates what extent in extratropical exists hindcasts operational prediction systems database. found exhibit extended compared troposphere. Prediction with higher stratospheric skill tend also analysis includes assessment events, including early and midwinter sudden...
The salts [emim]X (X = Br or I, emim 1-ethyl-3-methylimidazolium) and [emim][AlBr4] have been prepared as solid-state models of the [emim]X–AlX3(X Cl Br) ionic liquid systems. All three characterised crystallographically. I) are isomorphous composed ions in an extended hydrogen-bonded network. implications these results for both structure solvent properties liquids discussed.
Despite the long history of Fischer-Tropsch reaction, carbon monoxide has proven remarkably resistant to selective homologation under mild conditions. Here, we find that an organouranium(III) complex induces efficient reductive trimerization at room temperature and pressure. The result is a triangular, cyclic C 3 O 2– , or deltate, dianion held between two uranium(IV) units. bonding within unit its coordination U centers have been analyzed by x-ray diffraction density functional theory...
Getting down to business: Reduction of the LaIII tricyclopentadienide complex [LaCp′′3] (Cp′′=η5-1,3-(SiMe3)2C5H3) by K and [18]crown-6 or [2,2,2]cryptand produced thermally stable mononuclear crystalline lanthanate(II) salts. The La +2 oxidation state in these complexes was confirmed both solution (EPR) solid (EPR, SQUID, X-ray diffraction) supported a computational study. Supporting information for this article is available on WWW under...
The β-diketiminato complex [{HC(C(Me)2N-2,6-iPr2C6H3)2}Ca{N(SiMe3)2}(THF)] effects intermolecular hydrophosphination of a range alkenes and alkynes. In behavior reminiscent lanthanocene(III) catalysis, more electrophilic alkene is polymerized to phosphine-terminated macromolecules.
X-Ray structures of the isomorphous centrosymmetric crystalline Ge2R4 and Sn2R4[R = CH(SiMe3)2] reveal a trans-folded C2h M2C4 framework, with fold angle θ 32° for M Ge 41° Sn, but no twist MC2 planes about M–M axis. The distance [2.347(2)Å 2.768(1)Å Sn] is slightly shorter (4% Ge, 1.5% Sn) than in tetrahedral element, M∞. conformation each MR2 moiety M2R4 approximates to planar syn,anti(cf. Ca. syn,syn gaseous MR2), four ligands R– are oriented ‘paddle-wheel’ fashion. There consequently an...
The novel salts [emim]2[CoCl4] and [emim]2[NiCl4](emim = 1-ethyl-3-methylimidazolium cation) have been prepared for use as crystallographic models in an extended X-ray absorption fine structure (EXAFS) study ambient-temperature ionic liquids. characterized both spectroscopically crystallographically. crystals are isomorphous, contain two distinct anions with differing interactions within the hydrogen-bonded structures. implications of these results liquids discussed.
rac-Tris(divinyldisiloxane)diplatinum(0) 1 is obtained on reaction of [Pt(cod)2] with tetramethyldivinyldisiloxane. Detailed multinuclear NMR studies showed that solutions are almost identical to the catalytically active solution which used in hydrosilation unsaturated compounds.
The alkylating agent LiR [R = CH(SiMe3)2] reacts with [Ln(OC6H3But2-2,6)3](Ln La or Sm) under ambient conditions to yield [LnR3][Ln (1) Sm (2)], the first structurally characterised neutral homoleptic alkyls of lanthanide metals; crystalline compounds and (2) have C3 symmetry almost tetrahedral CLnC′ angles, Ln–C bonds 2.515(9)(1) 2.33(2)Å(2), unusually short Ln ⋯ CH3 contacts [3.121(9)(1) 2.85(3)Å(2)].
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA convenient and novel route to bis(.eta.-alkyne)platinum(0) other platinum(0) complexes from Speier's hydrosilylation catalyst H2[PtCl6].xH2O. X-ray structure of [Pt{(.eta.-CH2=CHSiMe2)2O}(P-t-Bu3)]Grish. Chandra, Peter Y. Lo, B. Hitchcock, Michael F. LappertCite this: Organometallics 1987, 6, 1, 191–192Publication Date (Print):January 1987Publication History Published online1 May 2002Published inissue 1 January...
Five new classes of crystalline, hydrocarbon-soluble group 3A metal (M) aryloxides are reported: [M(OAr)3], (1), [M(L)(OAr)3][L = tetrahydrofuran (thf) or P(O)Ph3], [M(OAr)2(µ-OAr)2Na(thf)2], Li[Yb(Cl)(OAr)3], and [{Y(Cl)(OAr)(µ-OAr)}2](Ar C6H2Me-4-But2-2,6), ranging for (1) from M3+ being the 3d°, 4d°, to 4fn(n= 0, 1, 2, 3, 9,10, 11, 13) ion; title compound (1)(M Sc) has an approximately trigonal planar ScO3 skeleton (Sc 0.13 Å out O3 plane) with av. Sc–O 1.869(15)Å, O–Sc–O 119.5(2)°,...
The stoichiometric reaction of 1 equiv CO with [(U(η-C8H6{SiiPr3-1,4}2)(η-Cp*)] affords the linear diuranium ynediolate complex [(U(η-C8H6{SiiPr3-1,4}2)(η-Cp*)]2(μ-η1:η1-C2O2) which does not react further to give deltate derivative [(U(η-C8H6{SiiPr3-1,4}2)(η-Cp*)]2(μ-η1:η2-C3O3). Spectroscopic and computational studies suggest a plausible mechanism for formation complex, in "zig-zag" species is key intermediate.
A series of triazenide complexes the heavier alkaline earths, Ca, Sr and Ba, have been synthesized by either protonolysis or salt metathesis routes. Although form [{Ar2N3}M{N(SiMe3)2}(THF)n] (M = n 2; M Sr, 3; Ar 2,6-diisopropylphenyl) [{Ar2N3}Ca(I)(THF)2]2 could be isolated characterized X-ray crystallography, solution studies revealed propensity these species to undergo Schlenk-like redistribution with formation [{Ar2N3}2M(THF)n] 1; 2). The latter compounds independently. In case large...
Amides of the heavier group 2 elements Ca, Sr, and Ba are effective precatalysts for atom-efficient addition phosphine P−H bonds to carbodiimides. A number intermediates within catalytic cycle have been identified by in situ NMR methods stoichiometric synthesis.
A least-squares refinement analysis of atomic positional and thermal parameters in a single crystal 1,2-dilauroyl-DL-phosphatidylethanolamine: acetic acid has been based on the X-ray diffraction intensities 1132 independent reflexions, assessed by automatic microdensitometry. The final unweighted discrepancy index is 0.16 with e.s.ds bond lengths ranging from 0.02 to 0.12 A. general features our earlier, lessprecise are confirmed. close-packed arrangement phospholipid molecules discussed...
Abstract A novel diagnostic tool is presented, based on polar-cap temperature anomalies, for visualizing daily variability of the Arctic stratospheric polar vortex over multiple decades. This visualization illustrates ubiquity extended-time-scale recoveries from sudden warmings, termed here polar-night jet oscillation (PJO) events. These are characterized by an anomalously warm lower stratosphere that persists several months. Following initial warming, a cold anomaly forms in middle...
Abstract Sudden stratospheric warmings (SSWs) contribute to intraseasonal tropospheric forecasting skill due their surface impacts. Recent studies suggest these impacts depend upon whether the polar vortex splits or is displaced during SSW. We analyze annular mode signatures of SSWs in a 1000 year IPSL‐CM5A‐LR simulation. Although small differences mean Northern Annular Mode (NAM) index following and displacements are found, sign not consistent for two independent SSW algorithms, over 50...
Abstract Major sudden stratospheric warmings (SSWs), vortex formation, and final breakdown dates are key highlight points of the polar vortex. These phenomena relevant for stratosphere‐troposphere coupling, which explains interest in understanding their future changes. However, up to now, there is not a clear consensus on projected changes robust, particularly Northern Hemisphere, possibly due short data record or relatively moderate CO 2 forcing. The new simulations performed under Coupled...