A5101912990- Organometallic Complex Synthesis and Catalysis
- Magnetism in coordination complexes
- Synthetic Organic Chemistry Methods
- Metal complexes synthesis and properties
- Inorganic and Organometallic Chemistry
- Metal-Catalyzed Oxygenation Mechanisms
- Catalytic Cross-Coupling Reactions
- Oxidative Organic Chemistry Reactions
- Synthesis and characterization of novel inorganic/organometallic compounds
- Radical Photochemical Reactions
- Asymmetric Hydrogenation and Catalysis
- Carbon dioxide utilization in catalysis
- Chemical Synthesis and Analysis
- Asymmetric Synthesis and Catalysis
- Catalytic C–H Functionalization Methods
- Catalytic Alkyne Reactions
- Advanced Polymer Synthesis and Characterization
- Atmospheric Ozone and Climate
- Molecular Junctions and Nanostructures
- Lanthanide and Transition Metal Complexes
- Spectroscopy and Laser Applications
- Ferrocene Chemistry and Applications
- Atmospheric chemistry and aerosols
- Synthesis and Catalytic Reactions
- Chemical Reactions and Isotopes
University of Michigan
2023
SUNY Upstate Medical University
2022
University of Helsinki
2022
University of British Columbia
1998-2018
Okanagan University College
2008-2018
Texas Orthopedic Hospital
2018
Louisiana State University
2007-2012
Rutherford Appleton Laboratory
2005-2010
University of Prince Edward Island
2001-2008
Research Complex at Harwell
2007
Radicals in check: The steric properties of the aryl substituents chromium β-ketiminato complexes can be tuned to achieve reversible radical trapping a growing poly(vinyl acetate) chain (see scheme; V-70=radical initiator, VOAc=vinyl acetate). Supporting information for this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z801498_s.pdf or from author. Please note: publisher not responsible content functionality any supporting supplied by authors. Any queries...
The ability of compounds CpCrII(nacnacAr,Ar) (Ar = Dipp, 1; Xyl, 2) to catalyze the atom transfer radical polymerization (ATRP) vinyl acetate has been explored using methyl 2-chloropropionate as initiator. Polymerizations were also carried out under reverse ATRP conditions with thermal initiation by 2,2′-azobis(4-methoxy2,4-dimethylvaleronitrile) (V-70) in presence CpCrIII(nacnacAr,Ar)Cl 3; 4). All data suggest that these processes are fact proceeding organometallic-mediated (OMRP)....
The new compounds CpCr(nacnacAr,Ar′) with nacnacAr,Ar′ = Ar−N---C(Me)---CHC(Me)---N−Ar′ (Ar Ar′ C6H2Me3-2,4,6 or mes, 2; C6H3Et2-2,6 dep, 3; Ar C6H3Me2-2,6 xyl and C6H3iPr2-2,6 dipp, 4) have been synthesized used in polymerization experiments addition to the previously known analogues xyl, 1, 5. were as moderators for of vinyl acetate (VAc) initiated by V-70, according an OMRP mechanism. alkylchromium(III) thermal initiator CpCr(nacnacxyl,xyl)(CH2CMe3) (8) was from CpCr(nacnacxyl,xyl)(OTs)...
The atmospheric chemistry of several gases used in industrial applications, C(4)F(9)OC(2)H(5) (HFE-7200), C(4)F(9)OCH(3) (HFE-7100), C(3)F(7)OCH(3) (HFE-7000) and C(3)F(7)CH(2)OH, has been studied. discharge flow technique coupled with mass-spectrometric detection to study the kinetics their reactions OH radicals as a function temperature. infrared spectra compounds have also measured. following Arrhenius expressions for were determined (in units cm(3) molecule(-1) s(-1)): k(OH + HFE-7200) =...
Abstract Organometallic‐mediated radical polymerization (OMRP) has emerged as a powerful new class of living controlled polymerization. In order to fulfill its potential in the vinyl acetate (VOAc) and other challenging monomers, effects ancillary ligands on metal‐alkyl bond dissociation energy OMRP reagents must be thoroughly explored. Recent results investigating structure‐activity relationships well‐defined cobalt, iron chromium complexes will discussed. The involvement intermediates...
It has previously been demonstrated that both [(C5Me5)Ir(PMe3)(CH=CH2)H] and [(C5Me5)Ir(PMe3)(H2C=CH2)] are formed when [(C5Me5)Ir(PMe3)] is thermolytically generated in the presence of ethylene. At higher temperatures, vinyl hydride converted to η2-ethylene adduct. Density functional theory now used investigate this reaction, using B3LYP functional, two types basis sets (LanL2DZ TZV*), models [(C5R5)Ir(PR3)] species (R=H CH3). The study consists full optimizations local minima, first-order...
A range of paramagnetic Cr(III) monohydrocarbyl complexes CpCr[(ArNCMe)2CH](R) (Ar = ortho-disubstituted aryl; R primary alkyl, trimethylsilylmethyl, benzyl, phenyl, alkenyl, or alkynyl) were synthesized to investigate how varying the steric and electronic properties group affected their propensity for Cr-R bond homolysis. Most prepared by salt metathesis known CpCr[(ArNCMe)2CH](Cl) compounds in Et2O with commercial RMgCl solutions, although more sterically demanding combinations Ar groups...
Reaction of new CpCr[(RN)<sub>2</sub>C<sub>6</sub>H<sub>4</sub>] complexes (R = SiMe<sub>3</sub>, CH<sub>2</sub>CMe<sub>3</sub>, Ph) with organic azides generates chromium imido complexes.
The minimum energy crossing point between the doublet and quartet potential surfaces of CpMoCl2(PH3)2 is calculated to lie 4.8 kcal mol−1 lower in than dissociative intermediate CpMoCl2(PH3). Implications for influence spin state changes on rates organometallic reactions are discussed.
The discovery of new applications in small-molecule activation, olefin polymerization, and organic synthesis has stimulated interest well-defined, paramagnetic, first-row transition-metal organometallic compounds. Single-electron-transfer reactions have proved to be a useful tool the targeted such complexes. In this review, several examples from recent literature are used illustrate strategy. case studies include β-diketiminato complexes Cr(II) Cr(III), three-coordinate Ni(II) species,...
The activation of iodomethane by the Cr(II) complex 1 to form Cr(III) iodide and methyl compounds 2 3 was monitored UV−visible spectroscopy. halide species were independently synthesized oxidation with lead(II) halides, compound prepared via salt metathesis triflate, their structures determined single-crystal X-ray diffraction.
A series of Cr(III) half-sandwich β-diketiminate complexes, CpCr[(ArNCMe)2CH]X, X = I (2), CH3 (3), or Cl (4), were prepared. Compared to previously communicated complexes with Ar 2,6-iPr2C6H3 (Dpp, a), less sterically demanding ligands such as 2,6-Me2C6H3 (Xyl, b), 2,4,6-Me3C6H2 (Mes, c), 2,6-Et2C6H3 (Dep, d) more readily synthesized via salt metathesis reactions. Iodide compounds 2b−d prepared by oxidation the corresponding Cr(II) species CpCr[(ArNCMe)2CH] 1b−d half an equivalent iodine....
Chromium(III) mesityl complexes were synthesized by protonolysis of chromocene with 1,3-diisopropylimidazolium chloride or DBU hydrochloride, salt metathesis MesMgBr, and single electron oxidation iodine.
Oxidation of CpCr[(XylNCMe)(2)CH] (Xyl = 2,6-Me(2)C(6)H(3)) with pyridine N-oxide or air generated the μ-oxo dimer, {CpCr[(XylNCMe)(2)CH]}(2)(μ-O). The dimer was converted to paramagnetic Cr(III) CpCr[(XylNCMe)(2)CH](X) complexes (X OH, O(2)CPh, Cl, OTs) via protonolysis reactions. related alkoxide OCMe(3), OCMe(2)Ph) were prepared by salt metathesis and characterized single crystal X-ray diffraction. interconversion their reduction back Cr(II) Mn powder monitored using UV-vis spectroscopy....
Reaction of Cp2Ti[η2-(CSiMe3)2] with an α-aryloxy ketone produces a Ti(IV) enolate aryloxide complex. Selective protonolysis the ligand or both Ti–OR bonds can be achieved various acids. The reaction 1-phenyl-2-phenoxyethanol is catalyzed by mixture NEt3 and [HNEt3]X (X = OTf, BPh4).
Oxidation of Cr[N(SiMe3)2]2(THF)2 with iodine and dicumyl peroxide results in tetrahedral Cr(IV) Cr[N(SiMe3)2]2I2 trigonal planar Cr(III) Cr[N(SiMe3)2](OCMe2Ph)2, respectively; both complexes have been characterised by single-crystal X-ray diffraction, are active for ethylene polymerisation alkylaluminium co-catalysts.
Research interest in non-metallocene olefin polymerization catalysts has led to advances the synthesis of well-defined paramagnetic organometallic complexes first-row transition metals, including chromium. Single component have been prepared using cationic Cr(III) alkyl with substituted cylopentadienyl or β-diketiminato ancillary ligands. High throughput screening strategies developed assist rapid evaluation structure-activity relationships. Density functional theoretical studies also proved...
Cyclopentadienyl chromium β-diketiminate catalysts are used for the radical cyclization of bromo and chloro acetals. Mn powder activated with PbBr2 or PbCl2 is stoichiometric reductant, γ-terpinene hydrogen atom donor. Although primary cyclized product can be isolated structurally characterized as Cr(III) complex, this substrate also reduced catalytically under mild photolysis conditions.
The CrII complexes CpCr[DppNC(Me)CHC(Me)NC6H4Y] (1; Dpp = 2,6-(Me2CH)2C6H3) were used to prepare the corresponding CrIII iodo (2) and methyl (3) mixed-aryl β-diketiminate compounds with Y OMe (a), CH3 (b), H (c), CF3 (d). Oxidation of precursors iodine gave CpCr[DppNC(Me)CHC(Me)NC6H4Y](I) (2a−d). 3a−d prepared by reaction iodomethane followed MeMgI. chloride 4a−d synthesized salt metathesis isolated CpCrCl2(THF) appropriate deprotonated β-diketiminate. structures paramagnetic 1b,c, 2a,b,...
Chromium cyclopentadienyl β-diketiminate catalysts have been used to form Ph2PCy from Ph2PY (Y = Cl, PPh2, H) and CyX (X Br, Cl) substrates. Manganese powder activated by PbX2 or Me3SiCl was as the stoichiometric reductant. The Cr(III) cyclohexyl intermediate has synthesized structurally characterized. observed variations in catalytic activity correlated with previously reactivity differences imparted modifying N-aryl substituents on ancillary ligand.