Synthesis of Organouranium(IV) Triflates from U(OTf)4 or from Alkyl or Amide Precursors

Abstract

The uranium(IV) triflate [U(OTf)4] (1) (OTf = OSO2CF3) gives stable adducts with Lewis bases, such as [U(OTf)4(py)] (2) (py = pyridine). The crystal structure of a solvate of [U(OTf)4(OPPh3)3] (3), which exhibits a bidentate OTf group, has been determined. Substitution of the triflate ligands of 1 with LiNEt2, Kacac (acac = MeCOCHCOMe), KCp (Cp = η‐C5H5), and K2COT (COT = η‐C8H8) has led to the formation of [U(NEt2)4], [U(acac)4], [U(Cp)3(OTf)] (4), and [U(COT)(OTf)2(py)] (5), respectively. However, the bis(cyclopentadienyl) compounds [U(Cp*)2(OTf)2] (6) (Cp* = η‐C5Me5) and [U(Cp)2(OTf)2(py)] (7) could not be prepared from 1. Complexes 4−7 have been isolated in good yields from the protonolysis reactions of the corresponding alkyl or amide precursors by means of pyridinium triflate. Compound 5 has also been prepared by treating [U(COT)2] with either [pyH][OTf] or 1 in pyridine. The crystal structures of [U(Cp)2(OTf)2(py)2] (8) and [U(COT)(OTf)2(OPPh3)2]·0.5py (9) have been determined.

Mixed‐Donor Amido–Siloxo Actinide(IV) Halide and Alkyl Complexes with an Aryl Cipso Interaction

“…This is in contrast to the observations for 1 – 5 but is consistent with the more electron rich nature of 7 compared with these other complexes as a result of the two η 5 ‐coordinated Cp rings. The U–(centroid) distances of the two Cp rings in 7 of 2.488 and 2.492 Å are comparable to the U–(centroid) distances observed in other bis‐Cp and ‐Cp* uranium complexes 75,76…”

Reductive silylation of Cp*UO2(MesPDIMe) promoted by Lewis bases

“…15 Finally, the trifluoromethanesulfonate species, 6-OPPh 3¸ was converted to the tetrakis(trifluoromethanesulfonate) compound, (Ph 3 PO) 2 U(OTf) 4 (7-OTf), previously described by Ephritikhine and coworkers (Scheme 1). 22 The formation of 7-I and 7-OTf from oxo-derived siloxide ligands proceeds cleanly, in high yields (72 -98%), with minimal work-up. We surmise this general procedure should be broadly applicable to generic uranium(IV) complexes containing siloxide ligands for the production of useful homoleptic tetra(halide) starting materials.…”

The vitality of uranium molecular chemistry at the dawn of the XXIst century

“…A facile preparation of unsolvated UI 3 , which is preferred in some cases, was found to proceed in high yield from iodine and hot uranium turnings, with inexpensive equipment. 4 The potential of uranium triflates in the synthesis of coordination and organometallic compounds 5 was assessed after the preparation of U(OTf) 3 and U(OTf) 4 by reaction of either U, UCl 3 or UH 3 with pure triflic acid at controlled temperature; U(OTf) 4 was also synthesized by treating UCl 4 with TfOH at 120 • C. 6 The Lewis base adduct [U(OTf) 3 (py) 4 ] was alternatively obtained by protonolysis of [U{N(SiMe 3 ) 2 } 3 ] with pyridinium triflate in pyridine while [U(OTf) 3 (MeCN) 3 ] n was formed by salt metathesis of [UI 3 (THF) 4 ] with KOTf in acetonitrile and crystallized as 1D chains in which the U(III) ions are bridged by three bidentate triflate ligands. 7 In contrast, dissolution of [UI 3 (THF)…”