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

Cation‐Mediated Conversion of the State of Charge in Uranium Arene Inverted‐Sandwich Complexes

“…(1-THF) complex (Scheme 1). The transformation of complex 2 into complex 1-THF starts immediately after dissolution of complex 2 in THF and is complete after 12 h. The displacement of the arene moiety by THF has precedents in U III -arene compounds, [54] but to the best of our knowledge has not been reported for diuranium inverted-sandwich complexes. Single crystals of compound 1-THF were obtained from a solution of complex 2 in THF.…”

“…This complex is thermally resistant in the solid state when heated to 70 °C for 2 h. However, proton NMR studies show that the toluene adduct of complex 2 decomposes in THF with loss of a toluene molecule affording the [U(OSi(O t Bu) 3 ) 3 (thf) 2 ] ( 1 ‐THF) complex (Scheme ). The transformation of complex 2 into complex 1 ‐THF starts immediately after dissolution of complex 2 in THF and is complete after 12 h. The displacement of the arene moiety by THF has precedents in U III –arene compounds,54 but to the best of our knowledge has not been reported for diuranium inverted‐sandwich complexes. Single crystals of compound 1 ‐THF were obtained from a solution of complex 2 in THF.…”

Synthesis and X-ray Crystal Structures of (C5HiPr4)Ln(BH4)2(THF)(Ln = Nd and Sm), Versatile Precursors for Polymerization Catalysts

“…The easy sublimation of 3 also indicates a monomeric structure, as is usually observed for analogous uranium compounds. [5] Scheme 1. Synthesis of complexes 1Ϫ3 Monopermethylated cyclopentadienyl lanthanide complexes are less numerous than the disubstituted ones, and most of the complexes obtained from the halide compounds are hexacoordinated complexes of general formula [Cp* LnX 2 (THF) 3 ] or [Cp*LnX 3 M(THF) 2 ] (Cp* ϭ C 5 Me 5 , X ϭ Cl or I, M ϭ Li or Na).…”

f‐Element Half‐Sandwich Complexes: A Tetrasilylcyclobutadienyl–Uranium(IV)–Tris(tetrahydroborate) Anion Pianostool Complex

“…[8] The four SiMe 3 groups are displaced out of the C 4 plane of the cyclobutadienyl core,and all bend away from the uranium ion with displacements ranging from 0.452 to 0.566 ;t his is comparable to the magnitude of out of plane displacements for methyl groups in sterically crowded tris(cyclopentadienyl) complexes, [19] but the anion component of 3 is not obviously sterically overloaded, and we address ap ossible electronic reason for this below.T he UÀHd istances span the range 2.34(10) to 2.51(10) ,but, as is inherent to X-ray diffraction, those bond metrics are not determined with great precision invalidating any detailed discussion, and so perhaps am ore meaningful metric is the U···B distances (range:2 .537(19) to 2.594 (17) ), which compare well to the U···B distances in [U(h 5 -C 5 H 5 )(BH 4 ) 3 ]( range:2 .46(4) to 2.57(5) ) [17] and [U-(h 6 -C 6 Me 6 )(BH 4 ) 3 ](range:2.49(4) to 2.69(3) ). [18] Lastly,the [Li(THF) 4 ] + cation is unremarkable so is not discussed any further.…”

“…Thes alient features of the uranium anion component of 3 are the coordination of one h 4 -cyclobutadienyl and three k 3 -tetrahydroborate ligands to uranium in ap ianostool half-sandwich structure (the hydrides were located in the Fourier Difference Map but refined with restraints). TheU ÀCdistances in 3 span the range 2.477(11) to 2.549 (12) ,w hich is 0.12-0.18 shorter than the U À Cdistances in I [6a] reflecting their terminal and bridging natures, [16] respectively,and the U À C cent distance is 2.290 (15) .I ti si nstructive to compare the average U À C distances in 3 (2.513 )t ot hose of [U(h 5 -C 5 H 5 )(BH 4 ) 3 ] (2.656 ) [17] and [U(h 6 -C 6 Me 6 )(BH 4 ) 3 ](2.927 ) [18] since each complex features a{ U(BH 4 ) 3 }u nit in ap ianostool half-sandwich structural motif;t he trend of increasing U À C distances nicely illustrates the effect on moving from formally dianionic (C 4 R 4 ) 2À to monoanionic (C 5 R 5 ) 1À to neutral (C 6 R 6 ) 0 ligands,adjusting for the increasing ring sizes and the fact that the uranium component of 3 is ac harge-rich anion and the hexamethylbenzene complex incorporates uranium(III) rather than uranium(IV). Thec yclobutadienyl ring C À C distances span the range 1.452(16) to 1.488 (17) ,w hich is typical of metal coordinated cyclobutadienyl ligands.…”