Monique Lance

Synthesis and crystal structure of the oxo-bridged bimetallic organouranium complex [(Me3SiC5H4)3U]2[μ-O]

Abstract The compound (Me 3 SiC 5 H 4 ) 3 U (I) reacts with CO 2 or N 2 O to give [(Me 3 SiC 5 H 4 ) 3 U] 2 [μ-O] (II), the crystal structure of which reveals presence of a linear U-O-U bridge with U-O distances of 2.1053 (2) A.

Simple Preparations of the Anhydrous and Solvent‐Free Uranyl and Cerium(IV) Triflates UO2(OTf)2 and Ce(OTf)4 − Crystal Structures of UO2(OTf)2(py)3 and [{UO2(py)4}2(μ‐O)][OTf]2

Treatment of UO3 with pure triflic acid TfOH at 110 °C or with boiling triflic anhydride TfOTf afforded [UO2(OTf)2] (1) in high yields. The latter was also prepared by the reaction of UO3 with TfOH in water, or by dehydration of [UO2(OTf)2(H2O)n] in boiling TfOTf. Anhydrous [Ce(OTf)4] (2) was similarly obtained from the commercially hydrated compound. X-ray analysis revealed that in [UO2(OTf)2(py)3] (3), the triflate ligands are monodentate whereas they are dissociated in [{UO2(py)4}2(μ-O)][OTf]2 (4).

BISPENTAMETHYLCYCLOPENTADIENYL URANIUM(IV) THIOLATE COMPOUNDS. SYNTHESIS AND REACTIONS WITH CO2 AND CS2

Abstract The bisthiolate uranium complexes [U(Cp*)2(SR)2] (R=Me, iPr, tBu, Ph) were synthesized by treatment of [U(Cp*)2(Cl)2] with NaSR; the crystal structure of [U(Cp*)2(SMe)2] was determined. Their reactions with CO2 or CS2 gave the insertion derivatives [U(Cp*)2(SR)(E2CSR)] (E=O and R=tBu; E=S and R=Me, iPr or tBu) and [U(Cp*)2(E2CSR)2] (E=O and R=tBu; E=S and R=Me or tBu); [U(Cp*)2(StBu)(S2CStBu)] was characterized by its crystal structure. Treatment of this latter with CO2 gave the mixed insertion complex [U(Cp*)2(O2CStBu)(S2CStBu)]. Thermolysis of the insertion compounds led to the reverse elimination reaction of CO2 and CS2. Reduction of [U(Cp*)2(O2CStBu)2] with Na(Hg) afforded the corresponding U(III) anionic complex.

Tetramethylphospholyluranium complexes and their pentamethylcyclopentadienyl analogues

Abstract The mono- and bis-(tetramethylphospholyl)uranium complexes [U(tmp)(Cl) 3 (L) 2 ] (tmp = C 4 Me 4 P, L = tetrahydrofuran or L 2 = dimethoxyet

Arene uranium borohydrides: synthesis and crystal structure of (η-C6Me6)U(BH4)3

Thermal decomposition of U(BH4)4 (I) in mesitylene afforded red crystals of (η-mesitylene)U(BH4)3 (II); displacement of the arene ligand of II by hexamethylbenzene gave (C6Me6)U(BH4)3 (III). The crystal structure of III revealed tetrahedral coordination, with the BH4 ligands eclipsed by three methyl substituents of the aromatic ring. The cyclopentadienyl complexes CpU(BH4)3, Cp2U(BH4)2Na, Cp3U(BH4)Na, and Cp3U(THF) were prepared from II.

Anionic triscyclopentadienyluranium(III) hydrides

Abstract Addition of H − to [(C 5 H 4 R) 3 U] (R  H, Me, SiMe 3 , or t Bu) or sodium amalgam reduction of the U IV hydrides [(C 5 H 4 R) 3 UH] (R  SiMe 3 , or t Bu) afforded the hydrido-bridged anions [(C 5 H 4 R) 3 UHU(C 5 H 4 R) 3 ] − (R  H or Me) or the monomeric anions [(C 5 H 4 R) 3 UH] − (R  SiMe 3 or t Bu). Crystals of [Na(18-crown-6)(THF) 2 ][(C 5 H 4 SiMe 3 ) 3 UHU(C 5 H 4 SiMe 3 ) 3 ] were obtained from an equimolar mixture of [Na(18-crown-6)][(C 5 H 4 SiMe 3 ) 3 UH] and [(C 5 H 4 SiMe 3 ) 3 U] and their structure determined.

Synthesis, structure and oxidative addition reactions of triscyclopentadienyluranium(III) nitrile complexes

Abstract The U III nitrile complexes [U(cp) 3 (NCR)1 (cp =η-C 5 H 5 ; R = Me, n Pr, i Pr or t Bu) have been prepared by treatment of [U(cp) 3 (THF)] (THF, tetrahydrofuran) with the corresponding nitrile; the crystal structures of [U(cp) 3 (NC n Pr)] and [U(cp) 3 (NC i Pr)] have been determined. Reaction of [U(cp) 3 (THF)] with benzonitrile at room temperature or thermolysis of the adducts [U(cp) 3 (NCR)] (R = Me or n Pr) afforded an equimolar mixture of the U IV compounds [U(cp) 3 (CN)] and [U(cp) 3 (R)] (R = Me, n Pr or Ph).

EXAFS analysis of aqueous and acetonitrile solutions of UO2-trilate with crown-ethers and aza-crowns. Crystals structures of the inclusion complexes UO2(18-crown-6)(CF3SO3)2 and UO2(dicyclohexyl-18-crown-6)(CF3SO3)2

Abstract Aqueous and acetonitrile solutions of uranyltriflatecrown systems have been studied by EXAFS and compared to the corresponding solids. In aqueous solution the uranyl moeity is surrounded by five water molecules. In acetonitrile solution, uranyl inclusion compounds are formed when the crown has six donor atoms. If the macrocycle has a different size, a direct uranyltriflate bond is observed, acetonitrile molecules complete the uranyl coordination. UO2(18-crown-6)(CF3SO3)2 and UO2(dicyclohexyl-18-crown-6)(CF3SO3)2 inclusion complexes have been structurally characterized by single-crystal X-ray diffraction: in both complexes, the uranyl is bonded to the six O atoms of the crown ether in an hexagonal bipyramidal coordination.

Influence of electronic factors on the structure and stability of uranium compounds. Tri-tert-butyl methoxide uranium(IV) complexes

Abstract The complexes (tritox)UCI3(THF)x (I) and (tritox)2UCI2(THF)2 (II) (tritox = tBu3CO, THF = tetrahydrofuran) have been prepared by treating UCI4 with (tritox)Li. Compund II was a precursor for a series of (tritox)2UX2 compounds (X = BH4, CH3COCHCOCH3, η-C3H5, CH2Ph). The uranium borohydride derivative (tritox)U(BH4)3(THF) (IX) was isolated from the reaction of U(BH4)4(THF)2 with (tritox)H and was successively transformed into (tritox)2U(BH4)2 (IV) and (tritox)3U(BH4) (XI) by treatment with (tritox)Li. The crystal structures of the trigonal bipyramidal compound IX and the pseudo tetrahedral complex XI provide clear evidence of the strong Oπ→U contribution to the metaloxygen bonds. The structure and stability of these tritox compounds are quite different from those of the isosteric cyclopentadienyl analogues, and reveal the determining role of the electronic factors.

Successive Inclusion of Water, [H3NCH2CH2NH3]2+ and [H3NCH2CH2NH2]+ in the Aromatic Cavity of (p‐Sulfonato)calix[4]arene

Titration of the sulfonic protons of (p-sulfonato)calix[4]arene (H8L) with two equivalents of ethylenediamine affords [H3NCH2CH2NH3]2[H4L(H2O)3]·H2O, a molecular complex in which water is included inside the macrocycle. Deprotonation of one of the phenolic groups expels the water molecules from the aromatic cavity, leading to the formation of [H3NCH2CH2NH3]1.5[(H3L)(H3NCH2CH2NH3)]·(H2O)5.5, which represents an unprecedented example of the inclusion of a dication in a calixarene. Further addition of ethylenediamine affords the mixed salt [H3NCH2CH2NH3]2[(H3L)(H3NCH2CH2NH2)]·(H2O)4.5 in which the monocation [H3NCH2CH2NH2]+ is preferentially bound to the cavity through a non-classical hydrogen bond involving an N-H···π facial aromatic contact. Inclusion phenomena are indicated both by NMR and X-ray structure determinations. In the same way as their inorganic-organic counterparts, these clay-like materials are organised into parallel organic-organic layers.