Synthesis of Tungsten Imido Alkylidene Complexes that Contain an Electron-Withdrawing Imido Ligand

Axtell, Jonathan C.; Schrock, Richard R.; Müller, Péter; Smith, Stacey J.; Hoveyda, Amir H.

doi:10.1021/om5006676

Cited by 13 publications

(5 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, a diionic tetraphenylporphyrin ruthenium 3,5-bisCF 3 bisimido complex reported by Gallo and co-workers features Ru–N–C angles of 139.8(3)° and 143.7(4)° which demonstrates that the lone pair of the N imido is not datively bound to the Ru center and is available for reactivity . Additionally, Schelter and co-workers reported a series of cerium imido complexes with 3,5-bisCF 3 substituents where the lone pair of the N imido is datively bound to alkali metal countercations, rather than the cerium center, resulting in acute Ce–N imido –C angles ranging from 125.4(2) to 157.3(4)°. , On the other hand, there are examples of metal imidos with 3,5-bisCF 3 substituents where the lone pair on the N imido is datively bound to the metal center resulting in a more linear angle, 166.8(2)–179.2(7)°. − These U–N imido –C angles suggest that there is a dative interaction between the uranium center and the lone pair on the N imido atom for 3-pF , 3-bisF , 3-Mes , and 3-Mes* . Interestingly, the acute U–N imido –C angle in 3-bisCF 3 suggests a weakened dative interaction.…”

Section: Results and Discussionmentioning

confidence: 99%

Conversion of Uranium(III) Anilido Complexes to Uranium(IV) Imido Complexes via Hydrogen Atom Transfer

et al. 2022

View full text Add to dashboard Cite

A family of low-valent uranium(III) anilido complexes supported by the bulky hydrotris(3,5-dimethylpyrazolyl)borate (Tp*) ligand was synthesized by combining Tp* 2 UBn (Bn = benzyl) (1-Bn) with anilines of varying steric bulk and electronic profiles, including 4fluoroaniline, 3,5-difluoroaniline, 3,5-bis(trifluoromethyl)aniline, 3,5dimethylaniline, 2,4,6-trimethylaniline, and 2,4,6-tri-t Bu-aniline. The corresponding uranium(III) anilido species, Tp*, and Tp* 2 UNH-(2,4,6-tri-t Bu-phenyl) (2-Mes*), were isolated, and reactivity was explored. Conversion to their respective uranium(IV) imido species (3-pF, 3-bisF, 3-bisCF 3 , 3-bisCH 3 , 3-Mes, and 3-Mes*) was achieved by hydrogen atom transfer using either Gomberg's dimer or the 2,4,6-tri-t Bu-phenoxy radical (•OMes*) which eliminates the need to use potentially explosive organic azides, a reagent that has been commonly used for the synthesis of uranium(IV) imido complexes. For comparison of yields and purity of all methods, the uranium imido complexes were also prepared using the corresponding organic azides. Where applicable, compounds were characterized by multinuclear NMR spectroscopy ( 1 H, 11 B, 19 F), infrared spectroscopy, electronic absorption spectroscopy, and single crystal X-ray crystallography.

show abstract

Section: Results and Discussionmentioning

confidence: 99%

Conversion of Uranium(III) Anilido Complexes to Uranium(IV) Imido Complexes via Hydrogen Atom Transfer

et al. 2022

View full text Add to dashboard Cite

show abstract

“…p -Toluenesulfonyl hydrazide ( p -Tos-NHNH 2 ) was purchased from Sigma-Aldrich and was used without further purification. Mo(NAr)(CHCMe 2 Ph)(O- t- Bu) 2 ( 1 ; NAr = N-2,6- i- Pr 2 C 6 H 3 ), W(N- t- Bu)(CHCMe 3 )(pyr)(OHMT) ( 2 , OHMT = O-2,6-(2,4,6-Me 3 C 6 H 2 ) 2 C 6 H 3 ), W(NAr)(CHCMe 2 Ph)(pyr)(OHMT) ( 3 ), W(N-2,6-Me 2 C 6 H 3 )(C 3 H 6 )(pyr)(OHIPT) ( 4 , OHIPT = O-2,6-(2,4,6- i- Pr 3 C 6 H 2 ) 2 C 6 H 3 ), W(O)(CHCMe 2 Ph)(Me 2 Pyr)(OHMT)(PMePh 2 ) ( 7 ), W(O)(CHCMe 2 Ph)(Me 2 Pyr)(OHMT)(MeCN) ( 8 ), W(O)(CHCMe 2 Ph)(Me 2 Pyr)(ODFT)(PMePh 2 ) ( 9 , ODFT = O-2,6-(C 6 F 5 ) 2 C 6 H 3 ), W(O)(CHCMe 2 Ph)(Me 2 Pyr)(OTPP)(PMePh 2 ) ( 10 , OTPP = O-2,3,5,6-Ph 4 C 6 H), W(O)(CHCMe 2 Ph)(Me 2 Pyr)(ODPP)(PMePh 2 ) ( 11 , ODPP = O-2,6-Ph 2 C 6 H 3 ), Mo(N- t- Bu)(CHCMe 3 )(pyr)(OHMT) ( 12 ), Mo(NAd)(CHCMe 3 )(pyr)(OHMT) ( 13 ; Ad = 1-adamantyl), Mo(NAr)(CHCMe 2 Ph)(Me 2 pyr)(ODPP) ( 14 ), Mo(NAr)(CHCMe 2 Ph)(pyr)(OHMT) ( 15 ), Mo(N-2,6-Me 2 C 6 H 3 )(CHCMe 3 )(pyr)(OHIPT) ( 16 ), Mo(N-2,6-Me 2 C 6 H 3 )(CHCMe 2 Ph)( rac -biphen) ( 17 , biphen =3,3′-( t- Bu) 2 -5,5′-6,6′-(CH 3 ) 4 -1,1′-biphenyl-2,2′-diolate), Mo(NAr)(CHCMe 2 Ph)( rac -biphen- t- Bu) ( 18 , biphen- t- Bu = 3,3′-( t- Bu) 2 -5,5′-( t- Bu) 2 -6,6′-(CH 3 ) 2 -1,1′-biphenyl-2,2′-diolate), Mo(NAd)(CHCMe 2 Ph)( rac -biphen- t- Bu) ( 19 ), Mo(N-2,6-Me 2 C 6 H 3 )(CHCMe 2 Ph)(THF)( rac -biphenCF 3 ) ( 20 , biphenCF 3 = 3,3′-( t- Bu) 2 -5,5′-(CF 3 ) 2 -6,6′-(CH 3 ) 2 -1,1′-biphenyl-2,2′-diolate), Mo(NAd)(CHCMe 2 Ph)(THF)( rac -biphenCF 3 ) ( 21 ), W(N-2,6-Me 2 C 6 H 3 )(CHCMe 2 Ph)( rac -biphen) ( 22 ), W(O)(CHCMe 2 Ph)(OHMT) 2 ( 23 ), W(O)(CHCMe 2 Ph)(OTPP) 2 (PMePh 2 ) ( 24 ), W(NC 6 F 5 )(CHCMe 3 )(ODFT) 2 ( 25 ), W(N-2,4,6-Cl 3 C 6 H 2 )(CHCMe 3 )(O-2,6-(CHPh 2 ) 2 -3-MeC 6 H 2 ) 2 ( 26a ), W(N-2,4,6-Br 3 C 6 H 2 )(CHCMe 3 )(O-2,6-(CHPh 2 ) 2 -3-MeC 6 H 2 ) 2 ( 26b ), W(N-2,4,6-Cl 3 C 6 H 2 )(CHCMe 3 )(OTf) 2 (dme), and W(O)(CHCMe 2 Ph)(Me 2 Pyr) 2 (PPh 2 Me) were prepared according to published procedures.…”

Section: Methodsmentioning

confidence: 99%

“…p-Toluenesulfonyl hydrazide (p-Tos-NHNH 2 ) was purchased from Sigma-Aldrich and was used without further purification. Mo(NAr)(CHCMe 27 and W(O)(CHCMe 2 Ph)(Me 2 Pyr) 2 (PPh 2 Me) 28 were prepared according to published procedures.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Stereospecific Ring-Opening Metathesis Polymerization (ROMP) of endo-Dicyclopentadiene by Molybdenum and Tungsten Catalysts

et al. 2015

Self Cite

View full text Add to dashboard Cite

We report the stereospecific ring-opening metathesis polymerization (ROMP) of endodicyclopentadiene (DCPD) by various well-defined molybdenum-based and tungsten-based alkylidene initiators. Tungsten MAP (MonoAryloxide Pyrrolide) initiators with the general formula W(X)(CHCMe 2 Ph)(Me 2 Pyr)(OAr) (X = arylimido, alkylimido, or oxo; Me 2 Pyr = 2,5dimethylpyrrolide; OAr = an aryloxide) yield cis,syndiotactic-poly(DCPD), while biphenolate alkylidene complexes with the general formula M(NR)(CHCMe 2 Ph)(biphen) (M = Mo or W; R = alkyl or aryl, biphen = (e.g.) 3,3′-(t-Bu) 2 -5,5′-6,6′-(CH 3 ) 4 -1,1′-biphenyl-2,2′-diolate) yield cis,isotactic-poly(DCPD). Subtle changes in the initiator can greatly alter the structure of the poly(DCPD)s that are formed. Cis,syndiotactic or cis,isotactic poly(DCPD)s (made with 50-1000 equiv of DCPD) are accessible within seconds to minutes in dichloromethane at room temperature. No isomerization or cross-linking reactions are observed, and addition of a chain transfer reagent (1-hexene) or the use of THF as a solvent does not decrease the stereospecificity of the polymerizations. Cis,syndiotactic and cis,isotactic poly(DCPD)s can be distinguished readily from each other by 13 C NMR spectroscopy. Hydrogenation of each stereoregular poly(DCPD) produces crystalline H-poly(DCPD)s that have melting points between 270 and 290 °C.

show abstract

“…Hoveyda and co-workers have shown that modification of the imido fragment to be more electron deficient and less sterically encumbered, in complexes of the type W(NAr)(CHCMe3)(ODBMP)2 (DBMP = 2,6-CHPh2-4-Me-C6H2), led to much higher rates of polymerisation of 2,3-dicarbomethoxynorbornadiene. 5 In 1975, Menapace et al reported that the selectivity of a metathesis catalyst comprised of WCl6, PhNH2 and Et3Al2Cl3 could be modified in favour of alkene dimerisation by increasing the amount of aluminium cocatalyst in the system. 6 Furthermore, addition of triethylamine into the system with EtAlCl2 as the cocatalyst resulted in selectivities >99% for the dimerisation of 1-hexene.…”

Section: Introductionmentioning

confidence: 99%

Selective ethylene oligomerisation using supported tungsten mono-imido catalysts

Wright

Williams

Turner

et al. 2017

Inorg. Chem. Front.

View full text Add to dashboard Cite

show abstract

Synthesis of Tungsten Imido Alkylidene Complexes that Contain an Electron-Withdrawing Imido Ligand

Cited by 13 publications

References 43 publications

Conversion of Uranium(III) Anilido Complexes to Uranium(IV) Imido Complexes via Hydrogen Atom Transfer

Conversion of Uranium(III) Anilido Complexes to Uranium(IV) Imido Complexes via Hydrogen Atom Transfer

Stereospecific Ring-Opening Metathesis Polymerization (ROMP) of endo-Dicyclopentadiene by Molybdenum and Tungsten Catalysts

Selective ethylene oligomerisation using supported tungsten mono-imido catalysts

Contact Info

Product

Resources

About