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Isolation of Elusive HAsAsH in a Crystalline Diuranium(IV) Complex.

ABSTRACT: The HAsAsH molecule has hitherto only been proposed tentatively as a short-lived species generated in electrochemical or microwave-plasma experiments. After two centuries of inconclusive or disproven claims of HAsAsH formation in the condensed phase, we report the isolation and structural authentication of HAsAsH in the diuranium(IV) complex [{U(Tren(TIPS) )}2 (?-?(2) :?(2) -As2 H2 )] (3, Tren(TIPS) =N(CH2 CH2 NSiPr(i) 3 )3 ; Pr(i) =CH(CH3 )2 ). Complex 3 was prepared by deprotonation and oxidative homocoupling of an arsenide precursor. Characterization and computational data are consistent with back-bonding-type interactions from uranium to the HAsAsH ?*-orbital. This experimentally confirms the theoretically predicted excellent ?-acceptor character of HAsAsH, and is tantamount to full reduction to the diarsane-1,2-diide form.

SUBMITTER: Gardner BM

PROVIDER: S-EPMC4691330 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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Isolation of Elusive HAsAsH in a Crystalline Diuranium(IV) Complex.

Gardner Benedict M BM Balázs Gábor G Scheer Manfred M Wooles Ashley J AJ Tuna Floriana F McInnes Eric J L EJ McMaster Jonathan J Lewis William W Blake Alexander J AJ Liddle Stephen T ST

Angewandte Chemie (International ed. in English) 20151028 50

The HAsAsH molecule has hitherto only been proposed tentatively as a short-lived species generated in electrochemical or microwave-plasma experiments. After two centuries of inconclusive or disproven claims of HAsAsH formation in the condensed phase, we report the isolation and structural authentication of HAsAsH in the diuranium(IV) complex [{U(Tren(TIPS) )}2 (μ-η(2) :η(2) -As2 H2 )] (3, Tren(TIPS) =N(CH2 CH2 NSiPr(i) 3 )3 ; Pr(i) =CH(CH3 )2 ). Complex 3 was prepared by deprotonation and oxidat ...[more]

PMID: 26510123

Similar Datasets

Isolation of Elusive HAsAsH in a Crystalline Diuranium(IV) Complex.

Project description:The HAsAsH molecule has hitherto only been proposed tentatively as a short-lived species generated in electrochemical or microwave-plasma experiments. After two centuries of inconclusive or disproven claims of HAsAsH formation in the condensed phase, we report the isolation and structural authentication of HAsAsH in the diuranium(IV) complex [{U(TrenTIPS)}2(?-?2:?2-As2H2)] (3, TrenTIPS=N(CH2CH2NSiPri3)3; Pri=CH(CH3)2). Complex 3 was prepared by deprotonation and oxidative homocoupling of an arsenide precursor. Characterization and computational data are consistent with back-bonding-type interactions from uranium to the HAsAsH ?*-orbital. This experimentally confirms the theoretically predicted excellent ?-acceptor character of HAsAsH, and is tantamount to full reduction to the diarsane-1,2-diide form.

| S-EPMC4955221 | biostudies-literature

An isolable, crystalline complex of square-planar silicon(IV).

Project description:The structure and reactivity of silicon(IV), the second most abundant element in our Earth's crust, is determined by its invariant tetrahedral coordination geometry. Silicon(IV) with a square-planar configuration (ptSi IV ) represents a transition state. Quantum theory supported the feasibility of stabilizing ptSi IV by structural constraint, but its isolation has not been achieved yet. Here, we present the synthesis and full characterization of the first square-planar coordinated silicon(IV). The planarity provokes an extremely low-lying unoccupied molecular orbital that induces unusual silicon redox chemistry and CH-agostic interactions. The small separation of the frontier molecular orbitals enables visible-light ligand-element charge transfer and bond-activation reactivity. Previously, such characteristics have been reserved for d-block metals or low-valent p-block elements. Planarization transfers them, for the first time, to a p-block element in the normal valence state.

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Isolation of an elusive phosphatetrahedrane.

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Crystalline Diuranium Phosphinidiide and ?-Phosphido Complexes with Symmetric and Asymmetric UPU Cores.

Project description:Reaction of [U(TrenTIPS )(PH2 )] (1, TrenTIPS =N(CH2 CH2 NSiPri3 )3 ) with C6 H5 CH2 K and [U(TrenTIPS )(THF)][BPh4 ] (2) afforded a rare diuranium parent phosphinidiide complex [{U(TrenTIPS )}2 (?-PH)] (3). Treatment of 3 with C6 H5 CH2 K and two equivalents of benzo-15-crown-5 ether (B15C5) gave the diuranium ?-phosphido complex [{U(TrenTIPS )}2 (?-P)][K(B15C5)2 ] (4). Alternatively, reaction of [U(TrenTIPS )(PH)][Na(12C4)2 ] (5, 12C4=12-crown-4 ether) with [U{N(CH2 CH2 NSiMe2 But )2 CH2 CH2 NSi(Me)(CH2 )(But )}] (6) produced the diuranium ?-phosphido complex [{U(TrenTIPS )}(?-P){U(TrenDMBS )}][Na(12C4)2 ] [7, TrenDMBS =N(CH2 CH2 NSiMe2 But )3 ]. Compounds 4 and 7 are unprecedented examples of uranium phosphido complexes outside of matrix isolation studies, and they rapidly decompose in solution underscoring the paucity of uranium phosphido complexes. Interestingly, 4 and 7 feature symmetric and asymmetric UPU cores, respectively, reflecting their differing steric profiles.

| S-EPMC5577518 | biostudies-other

Isolation of the Elusive Heptavanadate Anion with Trisalkoxide Ligands.

Project description:The unprecedented heptavanadate cluster has been isolated from reactions between trisalkoxide ligands and vanadate in water at pH = 2 as a series of alkylammonium [HxV7O18(H2O)((OCH2)3CR)](4-x)- salts (1-3, R = CH2OH; 4, R = CH3). Their structures have been determined and the partial stability of 4 in water assessed by a combination of multinuclear NMR spectroscopy and ESI-MS. The heptavanadate unit reported herein could represent an intermediate species in the formation of decavanadate that is blocked by attachment of tripodal ligands.

| S-EPMC9157487 | biostudies-literature

Caesium diuranium hexa-telluride.

Project description:Single crystals of CsU(2)Te(6) were synthesized from the reaction of U, Te, and Cs(2)Te(3) at 1273?K. CsU(2)Te(6) crystallizes in the space group Cmcm in the CsTh(2)Te(6) structure type. The asymmetric unit comprises one U (site symmetry m2m), one Cs (m2m; half-occupancy) and two Te atoms (m.. and m2m). The structure of CsU(2)Te(6) consists of infinite [U(2)Te(6)] layers perpendicular to [010] separated by Cs atoms. There are infinite Te-Te-Te linear chains along [001].

| S-EPMC3470122 | biostudies-literature

Facile N-functionalization and strong magnetic communication in a diuranium(v) bis-nitride complex.

Project description:Uranium nitride complexes are of high interest because of their ability to effect dinitrogen reduction and functionalization and to promote magnetic communication, but studies of their properties and reactivity remain rare. Here we have prepared in 73% yield the diuranium(v) bis-nitride complex [K2{[U(OSi(O t Bu)3)3]2(μ-N)2}], 4, from the thermal decomposition of the nitride-, azide-bridged diuranium(iv) complex [K2{[U(OSi(O t Bu)3)3]2(μ-N)(μ-N3)}], 3. The bis-nitride 4 reacts in ambient conditions with 1 equiv. of CS2 and 1 equiv. of CO2 resulting in N-C bond formation to afford the diuranium(v) complexes [K2{[U(OSi(O t Bu)3)3]2(μ-N)(μ-S)(μ-NCS)}], 5 and [K2{[U(OSi(O t Bu)3)3]2(μ-N)(μ-O)(μ-NCO)}], 6, respectively. Both nitrides in 4 react with CO resulting in oxidative addition of CO to one nitride and CO cleavage by the second nitride to afford the diuranium(iv) complex [K2{[U(OSi(O t Bu)3)3]2(μ-CN)(μ-O)(μ-NCO)}], 7. Complex 4 also effects the remarkable oxidative cleavage of H2 in mild conditions to afford the bis-imido bridged diuranium(iv) complex [K2{[U(OSi(O t Bu)3)3]2(μ-NH)2}], 8 that can be further protonated to afford ammonia in 73% yield. Complex 8 provides a good model for hydrogen cleavage by metal nitrides in the Haber-Bosch process. The measured magnetic data show an unusually strong antiferromagnetic coupling between uranium(v) ions in the complexes 4 and 6 with Neel temperatures of 77 K and 60 K respectively, demonstrating that nitrides are attractives linkers for promoting magnetic communication in uranium complexes.

| S-EPMC6438153 | biostudies-literature

An Inverted-Sandwich Diuranium μ-η(5):η(5)-Cyclo-P5 Complex Supported by U-P5 δ-Bonding.

Project description:Reaction of [U(Tren(TIPS))] [1, Tren(TIPS)=N(CH2CH2NSiiPr3)3] with 0.25 equivalents of P4 reproducibly affords the unprecedented actinide inverted sandwich cyclo-P5 complex [{U(Tren(TIPS))}2(μ-η(5):η(5)-cyclo-P5)] (2). All prior examples of cyclo-P5 are stabilized by d-block metals, so 2 shows that cyclo-P5 does not require d-block ions to be prepared. Although cyclo-P5 is isolobal to cyclopentadienyl, which usually bonds to metals via σ- and π-interactions with minimal δ-bonding, theoretical calculations suggest the principal bonding in the U(P5)U unit is polarized δ-bonding. Surprisingly, the characterization data are overall consistent with charge transfer from uranium to the cyclo-P5 unit to give a cyclo-P5 charge state that approximates to a dianionic formulation. This is ascribed to the larger size and superior acceptor character of cyclo-P5 compared to cyclopentadienyl, the strongly reducing nature of uranium(III), and the availability of uranium δ-symmetry 5f orbitals.

| S-EPMC4517156 | biostudies-literature

An Inverted-Sandwich Diuranium ?-?(5):?(5)-Cyclo-P5 Complex Supported by U-P5 ?-Bonding.

Project description:Reaction of [U(Tren(TIPS))] [1, Tren(TIPS)=N(CH2CH2NSiiPr3)3] with 0.25?equivalents of P4 reproducibly affords the unprecedented actinide inverted sandwich cyclo-P5 complex [{U(Tren(TIPS))}2(?-?(5):?(5)-cyclo-P5)] (2). All prior examples of cyclo-P5 are stabilized by d-block metals, so 2 shows that cyclo-P5 does not require d-block ions to be prepared. Although cyclo-P5 is isolobal to cyclopentadienyl, which usually bonds to metals via ?- and ?-interactions with minimal ?-bonding, theoretical calculations suggest the principal bonding in the U(P5)U unit is polarized ?-bonding. Surprisingly, the characterization data are overall consistent with charge transfer from uranium to the cyclo-P5 unit to give a cyclo-P5 charge state that approximates to a dianionic formulation. This is ascribed to the larger size and superior acceptor character of cyclo-P5 compared to cyclopentadienyl, the strongly reducing nature of uranium(III), and the availability of uranium ?-symmetry 5f orbitals.

| S-EPMC4955234 | biostudies-other

Atomic structures of respiratory complex III2, complex IV, and supercomplex III2-IV from vascular plants.

Project description:Mitochondrial complex III (CIII2) and complex IV (CIV), which can associate into a higher-order supercomplex (SC III2+IV), play key roles in respiration. However, structures of these plant complexes remain unknown. We present atomic models of CIII2, CIV, and SC III2+IV from Vigna radiata determined by single-particle cryoEM. The structures reveal plant-specific differences in the MPP domain of CIII2 and define the subunit composition of CIV. Conformational heterogeneity analysis of CIII2 revealed long-range, coordinated movements across the complex, as well as the motion of CIII2's iron-sulfur head domain. The CIV structure suggests that, in plants, proton translocation does not occur via the H channel. The supercomplex interface differs significantly from that in yeast and bacteria in its interacting subunits, angle of approach and limited interactions in the mitochondrial matrix. These structures challenge long-standing assumptions about the plant complexes and generate new mechanistic hypotheses.

| S-EPMC7815315 | biostudies-literature

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