skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: In search of tris(trimethylsilylcyclopentadienyl) thorium
Reduction of Cp′ 3 ThCl, Cp′ 3 ThBr, and Cp′ 3 ThI (Cp′ = C 5 H 4 SiMe 3 ) with potassium graphite generates dark blue solutions with reactivity and spectroscopic properties consistent with the formation of Cp′ 3 Th. The EPR and UV-visible spectra of the solutions are similar to those of crystallographically-characterized tris(cyclopentadienyl) Th( iii ) complexes: [C 5 H 3 (SiMe 3 ) 2 ] 3 Th, (C 5 Me 4 H) 3 Th, (C 5 t Bu 2 H 3 ) 3 Th, and (C 5 Me 5 ) 3 Th. Density functional theory (DFT) analysis indicates that the UV-visible spectrum is consistent with Cp′ 3 Th and not [Cp′ 3 ThBr] 1− . Although single crystals of Cp′ 3 Th have not been isolated, the blue solution reacts with Me 3 SiCl, I 2 , and HCCPh to afford products expected from Cp′ 3 Th, namely, Cp′ 3 ThCl, Cp′ 3 ThI, and Cp′ 3 Th(CCPh), respectively. Reactions with MeI give mixtures of Cp′ 3 ThI and Cp′ 3 ThMe. Evidence for further reduction of the blue solutions to a Cp′-ligated Th( ii ) complex has not been observed. The crystal structures of Cp′ 3 ThMe and (Cp′ 3 Th) 2 (μ-O) were also determined as part of these studies.  more » « less
Award ID(s):
1835909
PAR ID:
10187518
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
Dalton Transactions
Volume:
48
Issue:
44
ISSN:
1477-9226
Page Range / eLocation ID:
16633 to 16640
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, Chemical Science)
    Electrochemical measurements on tris(cyclopentadienyl)thorium and uranium compounds in the +2, +3, and +4 oxidation states are reported with C 5 H 3 (SiMe 3 ) 2 , C 5 H 4 SiMe 3 , and C 5 Me 4 H ligands. The reduction potentials for both U and Th complexes trend with the electron donating abilities of the cyclopentadienyl ligand. Thorium complexes have more negative An( iii )/An( ii ) reduction potentials than the uranium analogs. Electrochemical measurements of isolated Th( ii ) complexes indicated that the Th( iii )/Th( ii ) couple was surprisingly similar to the Th( iv )/Th( iii ) couple in Cp′′-ligated complexes. This suggested that Th( ii ) complexes could be prepared from Th( iv ) precursors and this was demonstrated synthetically by isolation of directly from UV-visible spectroelectrochemical measurements and reactions of with elemental barium indicated that the thorium system undergoes sequential one electron transformations. 
    more » « less
  2. ; ; (, Dalton Transactions)
    The reduction potentials (reported vs. Fc + /Fc) for a series of Cp′ 3 Ln complexes (Cp′ = C 5 H 4 SiMe 3 , Ln = lanthanide) were determined via electrochemistry in THF with [ n Bu 4 N][BPh 4 ] as the supporting electrolyte. The Ln( iii )/Ln( ii ) reduction potentials for Ln = Eu, Yb, Sm, and Tm (−1.07 to −2.83 V) follow the expected trend for stability of 4f 7 , 4f 14 , 4f 6 , and 4f 13 Ln( ii ) ions, respectively. The reduction potentials for Ln = Pr, Nd, Gd, Tb, Dy, Ho, Er, and Lu, that form 4f n 5d 1 Ln( ii ) ions ( n = 2–14), fall in a narrow range of −2.95 V to −3.14 V. Only cathodic events were observed for La and Ce at −3.36 V and −3.43 V, respectively. The reduction potentials of the Ln( ii ) compounds [K(2.2.2-cryptand)][Cp′ 3 Ln] (Ln = Pr, Sm, Eu) match those of the Cp′ 3 Ln complexes. The reduction potentials of nine (C 5 Me 4 H) 3 Ln complexes were also studied and found to be 0.05–0.24 V more negative than those of the Cp′ 3 Ln compounds. 
    more » « less
  3. ; ; (, Acta Crystallographica Section E Crystallographic Communications)
    null (Ed.)
    The green compound poly[(tetrahydrofuran)tris[μ-η 5 :η 5 -1-(trimethylsilyl)cyclopentadienyl]caesium(I)ytterbium(II)], [CsYb(C 8 H 13 Si) 3 (C 4 H 8 O)] n or [(THF)Cs(μ-η 5 :η 5 -Cp′) 3 Yb II ] n was synthesized by reduction of a red THF solution of (C 5 H 4 SiMe 3 ) 3 Yb III with excess Cs metal and identified by X-ray diffraction. The compound crystallizes as a two-dimensional array of hexagons with alternating Cs I and Yb II ions at the vertices and cyclopentadienyl groups bridging each edge. This, based off the six-electron cyclopentadienyl rings occupying three coordination positions, gives a formally nine-coordinate tris(cyclopentadienyl) coordination environment to Yb and the Cs is ten-coordinate due to the three cyclopentadienyl rings and a coordinated molecule of THF. The complex comprises layers of Cs 3 Yb 3 hexagons with THF ligands and Me 3 Si groups in between the layers. The Yb—C metrical parameters are consistent with a 4 f 14 Yb II electron configuration. 
    more » « less
  4. ; ; ; ; (, Dalton Transactions)
    Reaction of ( p -tol 3 P) 2 PtCl 2 and Me 3 Sn(CC) 2 SiMe 3 (1 : 1/THF/reflux) gives monosubstituted trans -Cl( p -tol 3 P) 2 Pt(CC) 2 SiMe 3 (63%), which with wet n -Bu 4 N + F − yields trans -Cl( p -tol 3 P) 2 Pt(CC) 2 H ( 2 , 96%). Hay oxidative homocoupling (O 2 /CuCl/TMEDA) gives all- trans -Cl( p -tol 3 P) 2 Pt(CC) 4 Pt(P p -tol 3 ) 2 Cl ( 3 , 68%). Reaction of 3 and Me 3 Sn(CC) 2 SiMe 3 (1 : 1/rt) affords monosubstituted all- trans -Cl( p -tol 3 P) 2 Pt(CC) 4 Pt(P p -tol 3 ) 2 (CC) 2 SiMe 3 (46%), which is converted by a similar desilylation/homocoupling sequence to all- trans -Cl[( p -tol 3 P) 2 Pt(CC) 4 ] 3 Pt(P p -tol 3 ) 2 Cl ( 7 ; 79%). Reaction of ( p -tol 3 P) 2 PtCl 2 and excess H(CC) 2 SiMe 3 (HNEt 2 /cat. CuI) gives trans -Me 3 Si(CC) 2 Pt(P p -tol 3 ) 2 (CC) 2 SiMe 3 (78%), which with wet n -Bu 4 N + F − affords trans -H(CC) 2 Pt(P p -tol 3 ) 2 (CC) 2 H (96%). Hay oxidative cross coupling with 2 (1 : 4) gives all- trans -Cl[( p -tol 3 P) 2 Pt(CC) 4 ] 2 Pt(P p -tol 3 ) 2 Cl ( 10 , 36%) along with homocoupling product 3 (33%). Reaction of 3 and Me 3 Sn(CC) 2 SiMe 3 (1 : 2/rt) yields all- trans -Me 3 Si(CC) 2 ( p -tol 3 P) 2 Pt(CC) 4 Pt(P p -tol 3 ) 2 (CC) 2 SiMe 3 ( 17 , 77%), which with wet n -Bu 4 N + F − gives all- trans -H(CC) 2 ( p -tol 3 P) 2 Pt(CC) 4 Pt(P p -tol 3 ) 2 (CC) 2 H (96%). Reaction of 3 and excess Me 3 P gives all- trans -Cl(Me 3 P) 2 Pt(CC) 4 Pt(PMe 3 ) 2 Cl ( 4 , 86%). A model reaction of trans -( p -tol)( p -tol 3 P) 2 PtCl and KSAc yields trans -( p -tol)( p -tol 3 P) 2 PtSAc ( 12 , 75%). Similar reactions of 3 , 7 , 10 , and 4 give all- trans -AcS[(R 3 P) 2 Pt(CC) 4 ] n Pt(PR 3 ) 2 SAc (76–91%). The crystal structures of 3 , 17 , and 12 are determined. The first exhibits a chlorine–chlorine distance of 17.42 Å; those in 10 and 7 are estimated as 30.3 Å and 43.1 Å. 
    more » « less
  5. ; ; ; ; ; ; (, Chemical Science)
    Commercially available benzophenone imine (HNCPh 2 ) reacts with β-diketiminato copper( ii ) tert -butoxide complexes [Cu II ]–O t Bu to form isolable copper( ii ) ketimides [Cu II ]–NCPh 2 . Structural characterization of the three coordinate copper( ii ) ketimide [Me 3 NN]Cu–NCPh 2 reveals a short Cu-N ketimide distance (1.700(2) Å) with a nearly linear Cu–N–C linkage (178.9(2)°). Copper( ii ) ketimides [Cu II ]–NCPh 2 readily capture alkyl radicals R˙ (PhCH(˙)Me and Cy˙) to form the corresponding R–NCPh 2 products in a process that competes with N–N coupling of copper( ii ) ketimides [Cu II ]–NCPh 2 to form the azine Ph 2 CN–NCPh 2 . Copper( ii ) ketimides [Cu II ]–NCAr 2 serve as intermediates in catalytic sp 3 C–H amination of substrates R–H with ketimines HNCAr 2 and t BuOO t Bu as oxidant to form N -alkyl ketimines R–NCAr 2 . This protocol enables the use of unactivated sp 3 C–H bonds to give R–NCAr 2 products easily converted to primary amines R–NH 2 via simple acidic deprotection. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email