Reaction Of Trans Research Articles

Potassium, ytterbium(II), and samarium(III) alkoxide complexes containing the <i>tris</i>((2-dimethylaminomethyl)phenyl)methoxide ligand: synthesis and structures

The reaction oftris((2-dimethylaminomethyl)phenyl)methanol ((2-Me2NCH2C6H4)3COH) with potassium hydride in THF at –35°C affords dimeric alkoxide {[(2-Me2NCH2C6H4)3CO]K(THF)}2(I) in a yield of 90%. The reaction of compound I with YbI2(THF)2(1 : 1, 25°C) gives the Yb(II) alkoxyiodide complex {[(2-Me2NCH2C6H4)3CO]Yb(μ-I)(THF)2}2(II) in a yield of 57%. Complex II in the crystalline state is dimeric due to two bridging iodide ligands. Unlike the Yb(II) compound, the exchange reaction of complex I with SmI2(THF)2 (1 : 1, 25°C) in THF followed by the addition of dimethoxyethane (DME) involves the oxidation of the metal to form the trivalent samarium complex [(2-Me2NCH2C6H4)3CO]2SmI (III), which is isolated in a yield of 60%. The molecular structures of the complexes are determined by X-ray diffraction (XRD) (CIF files CCDC nos. 2259700 (I), 2259701 (II), and 2259702 (III)).

The investigation on the synthesis, characterization and anticancer activity of Ru-based chelating diphosphine ligand compounds

Compound trans-[RuIII(dmpe)2Cl2]2(PF6)2 (2) (dmpe = 1, 2 - bis (dimethylphosphino) ethane) was obtained by directly reaction of trans-[RuII(dmpe)2Cl2] (1) with [Cp2FeIII(PF6)]. trans-[RuIII(dmpe)2Cl2]2(FeIIIX4)2 (X = Cl, 3; X = Br, 4) were prepared by reaction of compound 1 with FeX3 (X = Cl, Br), respectively. Compounds 2-4 were characterized by IR, electronic absorption spectra, elemental analysis and Single-crystal X-ray diffraction, respectively. Single-crystal X-ray diffraction studies indicate that the ruthenium atoms in compounds 2-4 all define a slightly distorted octahedron with a [RuP4Cl2] coordination core, and the iron atoms in anion FeX4− of compounds 3 and 4 displays the expected tetrahedron with a [FeX4]− coordination core. Both metal-to-ligand charge-transfer (MLCT) and ligand-to-metal charge-transfer (LMCT) transitions exhibit in the lectronic absorption spectra of compounds 2-4. The in vitro activity of compounds 1-4 was evaluated in A549 and HeLa as well as MCF7 cell lines. The relative cell viability of compounds 2-4 on A549, HeLa and MCF7 cancer cells is in the order of 2>3>4 >1 by CCK-8 method. Compounds 2-4 have better activity than that of cisplatin in higher concentration, especially compound 2.

Construction of a Boron Chain on a Single Metal by Dehydrocoupling of Borane Ligands.

Borane coordination, B-H borane bond activation, and borane catenation via metal-mediated dehydrocoupling to form electron-precise B-B bonds are reported. The reaction of trans-[M(IMes)2Cl4] (M = W, Mo) (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene) with borates Li[BH3R] (R = Mes, Dur; Mes = 2,4,6-Me3C6H2 and Dur = 2,3,5,6-Me4C6H) afforded the complexes [M(IMes)(η2-H2BR)2(η1-H2BR)] (M = W: R = Mes 1, R = Dur 3; M = Mo: R = Mes 2, R = Dur 4). Three borane ligands are coordinated in 1-4 to the group 6 metal atom via five (σ-B-H) bonds. Reaction of 1 with the phosphines PMe3 and PEt3, respectively, led to the elimination of one of the borane ligands and afforded the hydrido (σ-B-H)-boryl bis(σ-B-H)-borane complexes trans-[W(IMes)(PR3)(η1-HBMes)(η2-H2BMes)(H)] (R = Me 5, R = Et 6), in which the metal atom inserted into one of the remaining σ-B-H bonds of the borane ligands. Reaction of 1 with an additional equivalent borane BH2Mes resulted in borane dehydrocoupling and formation of complex [W(IMes)(η4-BH2Mes-BMes-BMes-BH2Mes)] 7, featuring a unique B4 chain as a ligand. Reaction of trans-[W(IMes)2Cl4] with NaBH4 also led to B-B coupling, and the metallaborane cluster [{W(IMes)(BH4)}2(B5H9)] 9 was formed, in which two tungsten atoms bridge a B5 chain.

Revisiting the early days of conjugated polyyne synthesis. Syntheses and structures of Bis(triethylsilyl) Polyynediyl Adducts Et3Si(C[tbnd]C)nSiEt3 previously regarded as Unisolable (n = 6, 8, 12)

An overview of bis(trialkylsilyl) polyynediyl adducts R3Si(CC)nSiR3 with n ≥ 5 is followed by syntheses of TESCxTES where x = 8, 12, 16, and 24 (TES = SiEt3; x = 2n). In a seminal 1972 study, the last three were presented as too unstable to isolate and thus only characterized by UV-visible spectroscopy. Although not a rational route, TESC24TES is consistently obtained from the reaction of trans-(C6F5)(p-tol3P)2Pt(CC)5SiEt3 and crude HC8TES under Hay oxidative cross coupling conditions. The latter contains some HC8H and TESC8TES. Hay oxidative homocouplings of HC4TES and crude HC8TES afford TESC8TES (83%) and TESC16TES (5%). A Cadiot-Chodkiewicz reaction of BrC4Br and HC4TES (2 equiv) yields TESC12TES (11%). All of these compounds are crystalline, and the crystal structures of TESC8TES and TESC16TES are determined. The 13C{1H} NMR and UV-visible properties are also compared.

Macrobicyclic Dibridgehead Di(trialkyl)pnictogens E((CH2) n )3E (E/n = As/10, As/12, As/14, Sb/14) and Their Cage-like Metal Complexes: Syntheses, Structures, and Homeomorphic Isomerizations.

Photolyses of trans-Fe(CO)3(As((CH2) n )3As) (n = a, 10; b, 12; c, 14) in the presence of PMe3, or reactions of trans-[Fe(CO)2(NO)(As((CH2) n )3As)]+ BF4 - and n-Bu4N+ Cl-, afford the air stable title complexes As((CH2) n )3As (8a-c) in 79-34% yields. With 8a, the in, in and out, out isomers are separable and each is crystallographically characterized. With 8b,c, the isomers rapidly interconvert by homeomorphic isomerization, but each crystallizes (contrathermodynamically) as an out, out isomer. Reactions of 8c with H2O2 or 8b with BH3 give 8c·2O or 8b·2BH3, respectively (85-94%). Reactions of 8c with MCl2 (M = Pt, Pd, Ni), Rh(CO)(Cl), and Fe(CO)3 sources afford the corresponding cage-like complexes trans-ML n (As((CH2)14)3As) (86-51%). The crystal structures of 8c·2O and the PtCl2 and PdCl2 adducts are determined and compared to those of 8a-c and diphosphorus analogs. The corresponding distibine Sb((CH2)14)3Sb is analogously prepared, but precursors necessary for the bismuth analog could not be accessed due to the diminished BiR3 Lewis basicity.

Synthesis and end-group control of soluble, high-molecular-weight hyperbranched poly(phenylene thienylene)s by non-stoichiometric A2 + B3 Suzuki-Miyaura polycondensation without gelation

Non-stoichiometric Suzuki-Miyaura polycondensation of tribromo monomer 1, containing a thienylene group, with diboronic acid (ester) monomer 7 in the presence of tBuPPd catalyst, which has a propensity for intramolecular catalyst transfer on a π-electron face, was investigated. We anticipated that the presence of thienylene groups in the obtained hyperbranched polymer would increase the detection sensitivity in matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and enable the analysis of the polymer end groups up to the high-molecular-weight region. We first conducted Suzuki-Miyaura reaction of several kinds of 1 with phenylboronic acid 2 in the presence of tBuPPd precatalyst 3. The reaction of tris(5-bromo-4-hexylthien-2-yl)benzene 1c with 2 afforded exclusively tri-substituted product 4c, indicating that the tBuPPd catalyst undergoes intramolecular catalyst transfer on 1c after the first and second substitutions of 1c with 2. The polycondensation of equimolar 1c and pinacol phenylenediboronate 7a (reaction site ratio of Br:BPin = 1.5:1.0 (BPin = pinacol boronate)) was then carried out in the presence of 3 for 3 h, affording hyperbranched polymer with Mn = 37500 without gelation. The product was purified by precipitation. The degree of polymerization (DP) was calculated from the absolute molecular weight, determined by multi-angle light scattering (MALLS) analysis, to be 200, which is a far higher than would be predicted from the Flory-Stockmayer theory at the critical gel point (DP = 6.6). Furthermore, the MALDI-TOF mass spectra showed two series of peaks due to polymer with boronate ends and boronate ends along with one cyclic unit up to m/z of about 7500, as we had expected. The absence of peaks due to polymer with Br ends indicates that the degree of branching (DB) of this hyperbranched polymer is 100 %.

Reactions of Platinum Terminal Polyynyl Complexes trans-(C6F5)(p-tol3P)2Pt(C≡C)nH (n = 2-4) and n-BuLi, Generation of Functional Equivalents of Pt(C≡C)nLi Species, and Derivatization with Organic and Inorganic Electrophiles.

Reactions of the title complexes and n-BuLi (1.5 equiv, -45 °C) afford functional equivalents of the deprotonated species trans-(C6F5)(p-tol3P)2Pt(C≡C)nLi (n = 2-4), as assayed by subsequent additions of MeI or Me3SiCl to give trans-(C6F5)(p-tol3P)2Pt(C≡C)nMe (66-52%) or trans-(C6F5)(p-tol3P)2Pt(C≡C)nSiMe3 (63-49%). However, 31P NMR data suggest more complicated mechanistic scenarios, and small amounts of the hydride complex trans-(C6F5)(p-tol3P)2PtH (independently synthesized from the chloride complex, AgClO4, and NaBH4) are detected in most cases. Analogous sequences involving trans-(C6F5)(p-tol3P)2Pt(C≡C)2H and benzyl bromide, D2O, or W(CO)6/Me3O+ BF4- similarly afford products with Pt(C≡C)2Bn, Pt(C≡C)2D, or Pt(C≡C)2C(OCH3)=W(CO)5 linkages. The crystal structures of the tungsten and corresponding SiMe3 adduct, the three Pt(C≡C)nMe species, and hydride complex are determined.

Controlled Modification of Triaminoguanidine-Based μ3 Ligands in Multinuclear [VIVO]/[VVO2] Complexes and Their Catalytic Potential in the Synthesis of 2-Amino-3-cyano-4H-pyrans/4H-chromenes.

Reaction of tris(2-hydroxybenzylidene)-triaminoguanidinium chloride (I·HCl) and tris(5-bromo-2-hydroxybenzylidene)-triaminoguanidinium chloride (II·HCl) with [VIVO(acac)2] (1:1 molar ratio) in refluxing methanol resulted in mononuclear [VIVO] complexes, [VIVO(H2L1')(MeOH)] (1) and [VIVO(H2L2')(MeOH)] (2), respectively, where I and II undergo intramolecular triazole ring formation. Aerial oxidation of 1 and 2 in MeOH in the presence of Cs2CO3 gave corresponding cis-[VVO2] complexes Cs[(VO2)(H2L1')] (3) and Cs[(VO2)(H2L2')] (4). However, reaction of an aerially oxidized methanolic solution of [VIVO(acac)2] with I·HCl and II·HCl in the presence of Cs2CO3 (in 1:1:1 molar ratio) gave mononuclear complexes Cs[(VO2)(H3L1)] (5) and Cs[(VO2)(H3L2)] (6) without intramolecular triazole ring formation. Similar anionic trinuclear complexes Cs2[(VO2)3(L1)] (7) and Cs2[(VO2)3(L2)] (8) were isolable upon increasing the amounts of the vanadium precursor and Cs2CO3 to 3 equiv to the reaction applied for 5 and 6. Keeping the reaction mixture of 1 in MeOH under air gave [VVO(H2L1')(OMe)] (9). Structures of 3, 7, 8, and 9 were confirmed by X-ray crystal structure study. A permanent porosity in the crystalline metal-organic framework of 7 confirmed by single-crystal X-ray investigation was further verified by the BET study. Along with a suitable reaction mechanism, these synthesized compounds were explored as effective catalysts for the synthesis of biomolecules 4H-pyran/4H-chromenes.

Chirality Generated by Hindered Rotations in Platinum(II)‐Pyridine Complexes

AbstractThe reaction of trans‐[Pt(DMSO)2MeCl] with 2‐alkylsubstituted pyridines pyR affords a series of complexes of the type [Pt(pyR)(DMSO)MeCl]. These complexes are rare examples of organometallic square‐planar complexes having four different ligands. Of the three possible geometric isomers, only the trans(N,S)‐[Pt(pyR)(DMSO)MeCl] was observed in solution and isolated in the solid state. However, the lack of chirality typical to square planar geometry can be resolved in several ways one of which is described in this paper. 1H NMR studies reveal diastereotopicity of the DMSO methyls, as well as the CH2 protons in the ethyl‐ and neopentyl‐pyridine complexes and the methyls in the isopropyl‐pyridine derivative. This observation can be ascribed to restricted rotations around the Pt−N bond, thus resulting in the presence of planar chirality for these complexes. Additionally, large downfield shifts in the 1H NMR spectra of the α C−H protons in the pyridine substituents suggested the presence of Pt⋯H−C interactions, confirmed via single crystal X‐ray studies in the case of the isopropyl complex [Pt(pyip)(DMSO)MeCl] (4), which shows an apical Pt⋯H interaction with a short 2.585 Å distance. DFT calculations shed light into the stability of these complexes and the influence of the pyridine‐substituent on their chiral configuration.

Monodisperse Molecular Models for the sp Carbon Allotrope Carbyne; Syntheses, Structures, and Properties of Diplatinum Polyynediyl Complexes with PtC20Pt to PtC52Pt Linkages.

Extended conjugated polyynes provide models for the elusive sp carbon polymer carbyne, but progress has been hampered by numerous synthetic challenges. Stabilities appear to be enhanced by bulky, electropositive transition-metal endgroups. Reactions of trans-(C6F5)(p-tol3P)2Pt(C≡C)nSiEt3 (n = 4-6, PtCxSi (x = 2n)) with n-Bu4N+F-/Me3SiCl followed by excess tetrayne H(C≡C)4SiEt3 (HC8Si) and then CuCl/TMEDA and O2 give the heterocoupling products PtCx+8Si, PtCx+16Si, and sometimes higher homologues. The PtCx+16Si species presumably arise via protodesilylation of PtCx+8Si under the reaction conditions. Chromatography allows the separation of PtC16Si, PtC24Si, and PtC32Si (from n = 4), PtC18Si and PtC26Si (n = 5), or PtC20Si and PtC28Si (n = 6). These and previously reported species are applied in similar oxidative homocouplings, affording the family of diplatinum polyynediyl complexes PtCxPt (x = 20, 24, 28, 32, 36, 40 in 96-34% yields and x = 44, 48, 52 in 22-7% yields). These are carefully characterized by 13C NMR, UV-visible, and Raman spectroscopy and other techniques, with particular attention to behavior as the Cx chain approaches the macromolecular limit and endgroup effects diminish. The crystal structures of solvates of PtC20Pt, PtC24Pt, and PtC26Si, which feature the longest sp chains structurally characterized to date, are analyzed in detail. All data support a polyyne electronic structure with a nonzero optical band gap and bond length alternation for carbyne.

Studies of κ2- and κ3-tripyridylamine complexes of ruthenium and π-stacking by pyridyls.

The reaction of tris(pyridin-2-yl)amine with [CyRuCl2]2 (Cy = p-isopropyltoluene or cymene) in refluxing diglyme led to the formation of cis-[RuCl2{κ2-(2-py)3N}2]·CHCl3 (1a) after recrystallization from chloroform/pentane, or cis-dichloridobis[tris(pyridin-2-yl)amine-κ2N,N']ruthenium(II) dichloromethane disolvate, [RuCl2(C15H12N4)2]·2CH2Cl2 or cis-[RuCl2{κ2-(2-py)3N}2]·2CH2Cl2 (1b). Treatment of 1a with one equivalent of silver(I) hexafluoridoantimonate in dichloromethane gave [RuCl{κ2-(2-py)3N}{κ3-(2-py)3N}][SbF6]·CH2Cl2 (2a). Crystallization of 2a from chloroform provided chlorido[tris(pyridin-2-yl)amine-κ2N,N'][tris(pyridin-2-yl)amine-κ3N,N',N'']ruthenium(II) hexafluoridoantimonate chloroform monosolvate, [RuCl(C15H12N4)2][SbF6]·CHCl3 or [RuCl{κ2-(2-py)3N}{κ3-(2-py)3N}][SbF6]·CHCl3 (2b). Complex 2a reacted with a further equivalent of silver(I) hexafluoridoantimonate to give [Ru{κ3-(2-py)3N}2][SbF6]2 (3). The reaction of (2-py)3N with [CyRuCl2]2 in dichloromethane followed by treatment with excess sodium hexafluoridoantimonate gave the known complex [CyRuCl{κ2-(2-py)3N}][SbF6] (4). Complex 2 is a rare example of a complex containing both κ2- and κ3-(2-py)3N. Intramolecular π-stacking interactions determine the orientation of the free pyridyl in the κ2 complexes. An interesting encapsulation of methylene chloride hydrogen-bonded tetramers was noted in one case.

Synthesis, characterization, luminescence and NLO properties of heterotrinuclear MII-RuII-MII (M=Ni/Zn) complexes composed of coordination and organometallic sites

A new series of heterotrinuclear complexes of the type [Ru(dppm)2((CCC6H4CCC6H3 (O)HCNC6H4X)Ni(L'))2] (1a-c) and [Ru(dppm)2((CCC6H4CCC6H3(O)HCNC6H4X)Zn(L'))2] (2a-c) were prepared by the reaction of trans-[Ru(dppm)2(CCC6H4CCC6H3(OH)HCNC6H4X)2] with Ni(II)/Zn(II) ions in presence of 8-hydroxyquinoline. (where, X= Cl, Br, I; L'= 8-hydroxyquinoline) All the complexes were characterized by elemental analysis, FT-IR, 1H NMR, ESI-MS, UV–visible and thermogravimetric studies. The electrochemical properties of all the complexes indicate quasireversible redox behaviour corresponding to Ru(II)-Ru(III) and Ni(II)/ Ni(III) for 1a-c and Ru(II)/Ru(III) for 2a-c and are susceptible to variation of substituent group on ligand. All complexes show room temperature luminescence corresponding to π→π* intraligand charge transfer (ILCT) transition. The emission wavelength of the complexes is finely tuned by increasing π-conjugation and variation of substituent groups in the complexes. The second harmonic generation (SHG) efficiency of the complexes was measured by Kurtz-powder technique indicating that all complexes displayed the second harmonic generation (SHG) property.

Cu4I4-cubane cluster based on tris(p-anisyl)arsine: Synthesis, crystal structure and photophysical properties

A new cubane cluster [Cu4I4(AsAn3)4] was synthesized in 82% yield by the reaction of tris(p-anisyl)arsine (AsAn3) with CuI. At ambient temperature, this cluster exhibits bright yellow-green phosphorescence (λmax = 546 nm) with the quantum yield of 35% and 4.1 μs decay time.

Hybrid organometallo-silica catalysts for sustainable visible-light promoted olefin isomerization

The use of visible light as a clean and affordable reagent has turned photocatalysis into a green and powerful tool in synthetic chemistry. However, most of these photocatalytic processes are carried out under homogeneous conditions, which requires expensive catalysts that are difficult to recover and recycle. One way to overcome this problem is to incorporate the visible-active species into porous solid matrices. However, integrating these active species into the matrix to achieve a stable and active heterogeneous photocatalyst is not easy, and has usually been done by post-synthetic strategies. Herein, we describe the use of the highly emissive cyclometalated complex [Ir(dfppy)2(dasipy)]PF6 as a building block for the in-situ synthesis of four different silica-based heterogeneous photocatalysts, and a related post-synthetic grafted material. These highly stable materials have been assessed in the energy transfer photo-isomerization reaction of trans- to cis-stilbene under blue light and mild conditions; showing not only high isomerization yields (ca. 80 %), but also easy recovery and excellent recyclability (up to 100 % after 7 cycles).

Two 3D Ln(III)-MOFs Based on Phosphineoxide Ligand: Synthesis, Structure Luminescent and Photocatalytic Properties.

Two new 3D metal-organic frameworks (MOFs) ZZUT1 and ZZUT2 were prepared through the reaction of tris-(4-carboxylphenyl) phosphineoxide (H3TPO) ligand with nitrate of neodymium and praseodymium by solvothermal method. The structure, fluorescence and photocatalytic properties of ZZUT1 and ZZUT2 were studied. The crystalline structure of two 3D Ln(III)-MOFs both exhibit triclinic system and P-1 space group. The results of fluorescence analysis showed that two 3D Ln(III)-MOFs could selectively recognize acetone molecule through the fluorescence quenching mechanism. Meanwhile, ZZUT1 and ZZUT2 showed good adsorption and degradation ability on organic dye methylene blue (MB) in photocatalytic condition, and the degradation efficiency can reach to more than 90%.

Dual Routes toward Observation of a trans-H2/Hydride Complex in an Iridium Pincer System and Hydrogenation Catalytic Activity

ion of chloride from a six-coordinate complex, trans-[Ir(H)(Cl)(iPr)4(POCOP)(PPh3)] (1) [(iPr)4(POCOP) = 2,6-bis(di-iso-propylphosphinito)benzene, κ3-C6H3-1,3-[OP(iPr)2]2], using NaBAr4f leads to the generation of a dinitrogen complex, trans-[Ir(H)(N2)(iPr)4(POCOP)(PPh3)][BAr4f] (6). Addition of H2 to [Ir(H)(N2)(iPr)4(POCOP)(PPh3)]+ (6) under extremely mild conditions (1 bar, 298 K) resulted in the reversible coordination of H2 to generate the cis-[Ir(H)(η2-H2)(iPr)4(POCOP)(PPh3)]+ (cis-11) complex. The cis-[Ir(H)(η2-H2)(iPr)4(POCOP)(PPh3)]+ complex (cis-11) isomerized to a trans isomer, trans-[Ir(H)(η2-H2)(iPr)4(POCOP)(PPh3)]+ (trans-11), at 253 K. The isomerization process has been studied and supported by computations. Employing an alternative route, protonation of the trans-[Ir(H)2(iPr)4(POCOP)(PPh3)] complex (2) at 183 K resulted in the formation of an identical, trans-[Ir(H)(η2-H2)(iPr)4(POCOP)(PPh3)]+ complex (trans-11); upon warming the sample, the trans-H2/hydride complex isomerized to the cis isomer above 253 K. Two independent routes to obtain trans-[Ir(H)(η2-H2)(iPr)4(POCOP)(PPh3)]+ (trans-11) species have been established. Reaction of trans-[Ir(H)(N2)(iPr)4(POCOP)(PPh3)][BAr4f] (6) with C2H4 gave the cis-[Ir(H)(η2-C2H4)(iPr)4(POCOP)(PPh3)]+ complex (cis-15), which also undergoes isomerization to yield an equilibrium mixture of cis/trans-[Ir(H)(η2-C2H4)(iPr)4(POCOP)(PPh3)]+ complexes (cis-15 and trans-15) at 253 K. The trans-[Ir(H)(N2)(iPr)4(POCOP)(PPh3)]+ complex (6) is an excellent catalyst for hydrogenation of ethylene to ethane under very mild conditions.

Reductive Elimination Reactions in Gold(III) Complexes Leading to C(sp3)-X (X = C, N, P, O, Halogen) Bond Formation: Inner-Sphere vs SN2 Pathways.

The reactions leading to the formation of C-heteroatom bonds in the coordination sphere of Au(III) complexes are uncommon, and their mechanisms are not well known. This work reports on the synthesis and reductive elimination reactions of a series of Au(III) methyl complexes containing different Au-heteroatom bonds. Complexes [Au(CF3)(Me)(X)(PR3)] (R = Ph, X = OTf, OClO3, ONO2, OC(O)CF3, F, Cl, Br; R = Cy, X = Me, OTf, Br) were obtained by the reaction of trans-[Au(CF3)(Me)2(PR3)] (R = Ph, Cy) with HX. The cationic complex cis-[Au(CF3)(Me)(PPh3)2]OTf was obtained by the reaction of [Au(CF3)(Me)(OTf)(PPh3)] with PPh3. Heating these complexes led to the reductive elimination of MeX (X = Me, Ph3P+, OTf, OClO3, ONO2, OC(O)CF3, F, Cl, Br). Mechanistic studies indicate that these reductive elimination reactions occur either through (a) the formation of tricoordinate intermediates by phosphine dissociation, followed by reductive elimination of MeX, or (b) the attack of weakly coordinating anionic (TfO- or ClO4-) or neutral nucleophiles (PPh3 or NEt3) to the Au-bound methyl carbon. The obtained results show for the first time that the nucleophilic substitution should be considered as a likely reductive elimination pathway in Au(III) alkyl complexes.

Examining the reactivity of tris(ortho-carboranyl)borane with Lewis bases and application in frustrated Lewis pair Si-H bond cleavage.

Reactions of tris(ortho-carboranyl)borane with Lewis bases reveals only small bases bind. The tremendous bulk and Lewis acidity is leveraged in frustrated Lewis pair Si-H cleavage with a wider range of Lewis bases and greater efficacy than B(C6F5)3.

Estudo Experimental e Teórico da Reação de Redução do Cis e Trans 4-tert-butil-2-X-Cicloexanona (X = F e Cl) com N-selectride

Estudo Experimental e Teórico da Reação de Redução do Cis e Trans 4-tert-butil-2-X-Cicloexanona (X = F e Cl) com N-selectride

Neutral and Cationic Complexes of Silicon(IV) Halides with Phosphine Ligands.

The reaction of SiI4 and PMe3 in n-hexane produced the yellow salt, [SiI3(PMe3)2]I, confirmed from its X-ray structure, containing a trigonal bipyramidal cation with trans-phosphines. This contrasts with the six-coordination found in (the known) trans-[SiX4(PMe3)2] (X = Cl, Br) complexes. The diphosphines o-C6H4(PMe2)2 and Et2P(CH2)2PEt2 form six-coordinate cis-[SiI4(diphosphine)], which were also characterized by X-ray crystallography, multinuclear NMR, and IR spectroscopy. Reaction of trans-[SiX4(PMe3)2] (X = Cl, Br) with Na[BArF] (BArF = [B{3,5-(CF3)2C6H3}4]) produced five-coordinate [SiX3(PMe3)2][BArF], but while Me3SiO3SCF3 also abstracted chloride from trans-[SiCl4(PMe3)2], the reaction products were six-coordinate complexes [SiCl3(PMe3)2(OTf)] and [SiCl2(PMe3)2(OTf)2] with the triflate coordinated. X-ray crystal structures were obtained for [SiCl3(PMe3)2][BArF] and [SiCl2(PMe3)2(OTf)2]. The charge distribution across the silicon species was also examined by natural bond orbital (NBO) analyses of the computed density functional theory (DFT) wavefunctions. For the [SiX4(PMe3)2] and [SiX3(PMe3)2]+ complexes, the positive charge on Si decreases and the negative charge on X decreases going from X = F to X = I. Upon going from [SiX4(PMe3)2] to [SiX3(PMe3)2]+, i.e., removal of X–, there is an increase in positive charge on Si and a decrease in negative charge on the X centers (except for the case X = F). The positive charge on P shows a slight decrease.