(1S,2S)-1,2-二苯基乙二胺修饰Ir/SiO_2催化苯乙酮及其衍生物不对称加氢(英文)

不添加任何稳定剂,在碱性条件下制备了5%Ir/SiO2催化剂,并用于催化苯乙酮的不对称加氢反应中,详细考察了碱和手性修饰剂种类、氢气压力、反应温度、(1S,2S)-1,2-二苯基乙二胺((1S,2S)-DPEN)浓度对反应的影响.在优化反应条件下,5%Ir/SiO2催化剂表现出较好的反应活性和对映选择性.其中,苯乙酮不对称加氢反应的对映选择性达70%.该催化剂不需要任何稳定剂,制备方法简单,催化性能稳定,通过简单的离心分离即可循环使用.     

手性二胺修饰的镍配合物催化苯乙酮及其衍生物的不对称加氢反应

本文研究了由手性修饰剂(S,S)D-DPEN(DPEN:1,2一二苯基乙二胺)在反应条件下与NiCl2(PPh3)2原位生成的手性催化剂对苯乙酮及其衍生物不对称加氢反应的催化性能,考察了反应温度、反应压力、(S,S)-DPEN浓度等变化因素对催化活性和对映选择性的影响。结果表明,在15℃,氢气压力为8.0MPa,乙醇作溶剂时,苯乙酮加氢产物(R)-苯乙醇的对映选择性达到了77.2%e.e。     

(1S,2S)-1,2-二苯基乙二胺修饰Ir/SiO2催化苯乙酮及其衍生物不对称加氢（英文）

不添加任何稳定剂,在碱性条件下制备了5%Ir/SiO2催化剂,并用于催化苯乙酮的不对称加氢反应中,详细考察了碱和手性修饰剂种类、氢气压力、反应温度、(1S,2S)-1,2-二苯基乙二胺((1S,2S)-DPEN)浓度对反应的影响.在优化反应条件下,5%Ir/SiO2催化剂表现出较好的反应活性和对映选择性.其中,苯乙酮不对称加氢反应的对映选择性达70%.该催化剂不需要任何稳定剂,制备方法简单,催化性能稳定,通过简单的离心分离即可循环使用.     

RuCl2(BISBI)[(R,R)-DPEN]催化苯乙酮不对称加氢反应研究

报道了配合物RuCl₂(BISBI)[(R,R)-DPEN] [BISBI＝2,2'-二(二苯膦亚甲基)-1,1'-联苯, DPEN＝1,2-二苯基乙二胺]的合成和表征, 并研究了其在苯乙酮不对称加氢反应中的催化性能. 考察了底物/催化剂物质的量比、碱浓度、反应温度和氢气压力等对催化活性和对映选择性的影响, 在苯乙酮/KOH/催化剂的物质的量比为30000∶250∶1, 氢气压力为2 MPa, 反应温度为35 ℃时, 苯乙酮的转化率和生成α-苯乙醇的对映选择性分别达到了100%和65% ee.     

Ru-(S)-BINAP/γ-Al2O3催化剂上苯乙酮及其衍生物的多相不对称加氢反应

 在温和条件下制备了Ru-(S)-BINAP/γ-Al2O3催化剂,考察了其催化苯乙酮及其衍生物不对称加氢的活性. 在KOH-异丙醇溶液中,在c(KOH)=0.04 mol/L,氢气压力5 MPa和10 ℃条件下,(1S,2S)-DPEN手性修饰剂修饰的Ru-(S)-BINAP/γ-Al2O3催化剂具有较高的活性和对映选择性,反应28 h后苯乙酮的转化率可达100%,(R)-苯乙醇的ee值可达75.0%.     

(1S,2S)-DPEN修饰的Ir/Al2O3催化苯乙酮及其衍生物的不对称加氢反应$

在碱性条件下制备了三氧化二铝负载的铱(Ir/γ-Al2O3)催化剂,并用于苯乙酮及其衍生物的不对称催化加氢反应.考察了不同的碱、碱浓度、手性二胺(1S,2S)-1,2-二苯基乙二胺[(1S,2S)-DPEN]浓度、反应温度和反应压力对催化剂及反应的影响.结果显示,在优化反应条件下,该催化剂表现出较高的催化活性和良好的对映选择性,其中异丁酰苯不对称催化加氢反应的对映选择性达到了80.3%.该催化剂不需要使用任何稳定剂,制备方法简单,催化性能稳定,通过简单的离心分离即可循环使用.     

(1S,2S)-DPEN修饰的3%Ir/SiO2/2TPP催化苄叉丙酮的不对称加氢

在温和的条件下制备了负载型3%(w)Ir/SiO2/2TPP(三苯基膦)催化剂, 并且考察了(1S,2S)-1,2-二苯基乙二胺[(1S,2S)-DPEN]作为手性修饰剂对其催化苄叉丙酮不对称加氢反应性能的影响. 结果表明, 手性修饰剂(1S,2S)-DPEN的加入, 对苄叉丙酮不对称加氢反应活性和C=O加氢的选择性都有很好的促进作用. 经优化条件, 在40 ℃下, LiOH浓度为0.375 mol·L-1的甲醇溶液中, 氢气压力为6 MPa, 反应8 h后, 苄叉丙酮的转化率大于99.0%, 对不饱和醇的选择性大于99.0%, 不饱和醇的对映选择性(ee)值达到48.1%.     

负载型催化剂HPW/SBA-15的合成及其在2-萘甲醚乙酰化反应中的应用

采用浸渍法制备了SBA-15负载磷钨酸（HPW）催化剂HPW/SBA-15（Cat）,其结构和性能经XRD, IR和NH₃-TPD表征。将 Cat 应用于2-萘甲醚（1）和乙酸酐（2）的傅 克酰基化反应,考察了不同负载量的催化剂、反应时间、催化剂用量、原料摩尔比、反应温度对2-萘甲醚酰基化反应的转化率和主产物选择性的影响。结果表明:Cat₄₀ 0.05 g,反应5 h,n(1) ：n(2)=1：4,反应温度120 ℃时,1的转化率为92.59%,主产物2-甲氧基-1-萘乙酮的选择性达99.22%。     

(1S, 2S)-DPEN修饰的负载型钌-铑双金属催化剂催化苯乙酮及其衍生物的不对称加氢

制备了以三苯基膦(PPh3)作为助剂的Ru-Rh/γ-Al2O3 催化剂, 在氢氧化钾的异丙醇溶液中, 用(1S, 2S)-DPEN [(1S, 2S)-1,2-diphenylethane-1,2-diamine]作手性修饰剂对苯乙酮及其衍生物进行不对称催化加氢, 此催化剂表现出较高的催化活性和良好的对映选择性. 优化反应条件, 苯乙酮、乙基苯基酮和异丙基苯基酮的转化率分别达到92.5%, 95.9%, 100%, 生成(R)-构型产物的ee值分别达到79.6%、81.2%和81.4%.     

MCM-41负载钴催化H_2O_2氧化四氢萘合成α-四氢萘酮

比较了醋酸溶液中过渡金属(Fe、Co、Ni、Ce、Cu、La、Zr或Cr)掺杂MCM-41催化过氧化氢氧化四氢萘合成α-四氢萘酮的转化率和选择性,发现其中Co/MCM-41的催化活性最好。探讨了Co/MCM-41作催化剂时反应温度、反应时间、催化剂用量等对四氢萘氧化的转化率和形成四氢萘酮选择性的影响,确定了较优的反应条件:m(四氢萘)∶m(催化剂)=12.5∶1;反应温度T=383 K,反应时间8 h。四氢萘的转化率达94.7%,α-四氢萘酮的选择性达到70.3%。在反应体系中,Co/MCM-41是一种固体非均相催化剂。催化剂Co/MCM-41可回收重复使用3次,催化活性基本不变。     

Vanadium(II) alkyls. Synthesis and X-ray crystal structures of trans-VMe2(dmpe)2 and cis-V(CH2SiMe3) 2(dmpe)2

Treatment of the vanadium(II) tetrahydroborate complex trans-V(η¹-BH₄)₂(dmpe)₂ with (trimethylsilyl) methyllithium gives the new vanadium(II) alkyl cis-V(CH₂SiMe₃)₂(dmpe)₂, where dmpe is the chelating diphosphine 1,2-bis(dimethylphosphino)ethane. Interestingly, this complex could not be prepared from the chloride starting material VCl₂(dmpe)₂. The CH₂SiMe₃ complex has a magnetic moment of 3.8 μ_B, and has been characterized by ¹H NMR and EPR spectroscopy. The cis geometry of the CH₂SiMe₃ complex is somewhat unexpected, but in fact the structure can be rationalized on steric grounds. The X-ray crystal structure of cis-V(CH₂SiMe₃)₂(dmpe)₂ is described along with that of the related vanadium(II) alkyl complex trans-VMe₂(dmpe)₂. Comparisons of the bond distances and angles for VMe₂(dmpe) ₂, V---C = 2.310(5) Å, V---P = 2.455(5) Å, and P---V---P = 83.5(2)° with those of V(CH₂SiMe₃)₂(dmpe)₂, V---C = 2.253(3) Å, V---P = 2.551(1) Å, and P ---V---P = 79.37(3)° show differences due to the differing trans influences of alkyl and phosphine ligands, and due to steric crowding in latter molecule. The V---P bond distances also suggest that metal-phosphorus π-back bonding is important in these early transition metal systems. Crystal data for VMe₂(dmpe)₂ at 25°C: space group P2₁/n, with a = 9.041(1) Å, b = 12.815(2) Å, c = 9.905(2) Å, β = 93.20(1)°, V = 1145.8(5) ų, Z = 2, R_F = 0.106, and R_wF =0.127 for 74 variables and 728 data for which I 2.58 σ(I); crystal data for V(CH₂SiMe₃)₂(dmpe)₂ at −75°C: space group C2/c, with a = 9.652(4) Å, b = 17.958(5) Å, c = 18.524(4) Å, β = 102.07(3)°, V= 3140(3) ų, Z = 4, R_F = 0.033, and R_wF = 0.032 for 231 variables and 1946 data for which I 2.58 σ(I).     

Nuclear quadrupole resonances of α-(CH3)2 TeX2 (X=Cl, Br, I) and (CH3)2 TeI4

NQR spectra were observed for α-(CH₃)₂ TeX₂ (X=Cl, Br, I) and (CH₃)₂ TeI₄ at various temperatures. The two ⁸¹Br NQR lines were observed above 110 K in α-(CH₃)₂TeBr₂. The characteristic temperature dependence of the ¹²⁷I NQR line in α-(CH₃)₂ TeI. can be explained by the 3c—4e bond of the linear I---Te---I group. The positive temperatures dependence of the lowest ¹²⁷I NQR line in (CH₃)₂TeI₄ is discussed on the basis of the electron population calculated from Townes—Dailey treatment.     

Preparation and electrochemical behaviour of dinuclear platinum complexes containing NCN ligands (NCN=[C6H3(Me2NCH2)2-2,6]). The crystal structure of [C6H3(Me2NCH2)2-1,3-(CC)-5]2

A series of homodinuclear Pt compounds containing the anionic, potentially terdentate NCN ligand (NCN=[C₆H₃(Me₂NCH₂)₂-2,6]⁻) or its 4-ethynyl derivative were prepared. The two platinum centres are linked together in two different fashions: (i) directly linked by an ethynyl or diethynylphenyl group (head-to-head) and (ii) indirectly bonded by a ethynyl- or butadiynyl-linked bis-NCN ligand (tail-to-tail). The reaction of the head-to-head σ,σ′-ethynylide complex {Pt}CC{Pt} ({Pt}=[Pt(C₆H₃{CH₂NMe₂}₂-2,6)]⁺) with [CuCl]_n yields {Pt}Cl and [Cu₂C₂]_n, while with [Cu(NCMe)₄][BF₄] a Cu(I) bridged complex was formed: [(η²-{Pt}CC{Pt})₂Cu][BF₄]. The results of cyclic voltammetry experiments reveal that both connection modes of the two platinum centres lead to electrochemically independent Pt–NCN units. The X-ray crystal structure analysis of the neutral, tail-to-tail bridging butadiyne bis-NCNH ligand [C₆H₃(CH₂NMe₂)-1,3-(CC)-5]₂ is reported.     

Preparation and structural characterization of [RuCl2(CO)2{Te(CH2SiMe3)2}2] and [RuCl2(CO){Te(CH2SiMe3)2}3]

The objective of the present work was to synthesize mononuclear ruthenium complex [RuCl₂(CO)₂{Te(CH₂SiMe₃)₂}₂] (1) by the reaction of Te(CH₂SiMe₃)₂ and [RuCl₂(CO)₃]₂. However, the stoichiometric reaction affords a mixture of 1 and [RuCl₂(CO){Te(CH₂SiMe₃)₂}₃] (2). The X-ray structures show the formation of the cis(Cl), cis(C), trans(Te) isomer of 1 and the cis(Cl), mer(Te) isomer of 2. The ¹²⁵Te NMR spectra of the complexes are reported. The complex distribution depends on the initial molar ratio of the reactants. With an excess of [RuCl₂(CO)₃]₂ only 1 is formed. In addition to the stoichiometric reaction, a mixture of 1 and 2 is observed even when using an excess of Te(CH₂SiMe₃)₂. Complex 1 is, however, always the main product. In these cases the ¹²⁵Te NMR spectra of the reaction solution also indicates the presence of unreacted ligand.     

The designed synthesis and characterization of two novel heterometallic trinuclear incomplete cubane-like clusters [(CH3CH2)4N]{(M2CuS4)}(S2C2H4)2(PPh3) (M = Mo, W)

Two novel heterometallic trinuclear incomplete cubane-like clusters [(CH₃CH₂)₄N][{M₂CuS₄}(edt)₂(PPh₃)] (M = Mo, W) have been synthesized by reaction of [(CH₃CH₂)₄N]₂[M₂S₄(edt)₂] (M = Mo, W) with Cu(PPh₃)₂(dtp) [where edt is 1,2-ethane-dithiolato ligand, dtp is S₂P(OCH₂CH₃)₂⁻]. The two crystals are isomorphous in space group P1 (No. 1). The unit cell contains two independent molecules, but the two discrete anions have the same orientation for the PPh₃ ligands along one axis so the space group is undoubtedly non-centrosymmetric. The discrete anion contains two edt ligands and one PPh₃ ligand attached to one incomplete cubane-like cluster core {M₂CuS₄}³⁺ (M = Mo, W). The bond lengths of Mo---Mo[W---W] and the two Mo---Cu[W-Cu] are 2.852(2)[2.844(1)], 2.802(2)[2.765(3)], 2.760(2)[2.762(3)] Å, respectively. The M ₂S₄(edt)₂ (M = Mo, W) moiety remains almost unchanged, except that for the compound 1 the Mo=S double bond length elongates from av. 2.10 to av. 2.165 Å. The title clusters provide a new type of unsymmetric μ₂-bridging sulphido ligand. The incomplete cubane-like cluster core {Mo₂CuS₄}³⁺ of compound 1 is distorted because the two Cu---μ₂---S bond lengths are significantly different (2.313 Å and 2.409 Å), but the core {W₂CuS₄}³⁺ of compound 2 has approximately C_s symmetry. The IR spectra of the two title clusters and two starting materials are assigned.     

1,2-Eliminations from (CH3)2NH+CH2CH3 and (CH3)2NH 2+ : Guided dissociations

1,2-Eliminations are a varied and extensive set of dissociations of ions in the gas phase. To understand better such dissociations, elimination of CH₂=CH₂ and CH₃CH₃ from (CH₃)₂NH⁺CH₂CH₃ (1) and of CH₄ from (CH₃)₂NH₂⁺ are characterized by quantum chemical calculations. Stretching of the CN bond to ethyl is followed by shift of an H from methyl to the bridging position in ethyl and then to N to reach (CH₃)₂NH₂⁺ + CH₂=CH₂ from 1. CH₃CH₃ elimination by H-transfer to C₂H₅⁺ to form CH₃NH⁺=CH₂ + CH₃CH₃ also takes place. (CH₃)₂NH₂⁺ eliminates methane by CN bond extension followed by β-H-transfer to give CH₂=NH⁺ + CH₄. Low-energy reactions resembling complex-mediated 1,2-eliminations occur and constitute a hitherto largely unrecognized type of reaction. As in many complex-mediated reactions, these reactions transfer H between incipient fragments. They are distinguished from complex-mediated processes by the fragments not being able to rotate freely relative to each other near the transition state for reaction, as they do in complexes. Most 1,2-eliminations are ion-neutral complex-mediated, occur by the just described lower energy reactions, have 1,1-like transition states, or utilize highly asynchronous 1,2 transition states. All of these avoid synchronized 1,2-transition states that would violate conservation of orbital symmetry.     

Crystal Structure of Ternary Molybdate Rb5FeHf(MoO4)6 — a New Phase in the Rb2MoO4-Fe2(MoO4)3-Hf(MoO4)2 System

Physicochemical analysis (XRPA, DTA) was used to study phase equilibria in a ternary salt system Rb₂MoO₄-Fe₂(MoO₄)₃-Hf(MoO₄)₂ in the subsolidus region. Ternary molybdates with compositions 5:1:3, 5:1:2, and 1:1:1 have been found and synthesized. Crystal and thermal characteristics have been determined. Single crystals of the ternary molybdate Rb₅FeHf(MoO₄)₆ with a composition of 5:1:2 were grown. The crystal structure of the compound was solved using X-ray diffractometry (CAD-4 automatic diffractometer, MoK _α radiation, 1766 F(hkl), R = 0.0298). Hexagonal crystals with unit cell dimensions: a = b = 10.124(1) Å, c =15.135(3) Å, V = 1343.4(4) ų, Z = 2, ρ_calc = 4.008 g/cm³, space group P6₃. The mixed three-dimensional framework of the structure is formed from two sorts of MoO₄ tetrahedra and Fe and Hf octahedra linked through their common O-vertices. Rubidium atoms of three varieties occupy the large voids of the framework.Original Russian Text Copyright © 2004 by B. G. Bazarov, R. F. Klevtsova, A. D. Tsyrendorzhieva, L. A. Glinaskaya, and Zh. G. Bazarova__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1038–1043, November–December, 2004.     

Synthesis and reaction chemistry of 4-nitrile-substituted NCN-pincer palladium(II) and platinum(II) complexes (NCN = [NC-4-C6H2(CH2NMe2)2-2,6])

Nitrile-functionalized NCN-pincer complexes of type [MBr(NC-4-C₆H₂(CH₂NMe₂)₂-2,6)] (6a, M = Pd; 6b, M = Pt) (NCN = [C₆H₂(CH₂NMe₂)₂-2,6]⁻) are accessible by the reaction of Br-1-NC-4-C₆H₂(CH₂NMe₂)₂-2,6 (2b) with [Pd₂(dba)₃ · CHCl₃] (5a) (dba = dibenzylidene acetone) and [Pt(tol-4)₂(SEt₂)]₂ (5b) (tol = tolyl), respectively. Complex 6b could successfully be converted to the linear coordination polymer {[Pt(NC-4-C₆H₂(CH₂NMe₂)₂-2,6)](ClO₄)}_n (8) upon its reaction with the organometallic heterobimetallic π-tweezer compound {[Ti](μ-σ,π-CCSiMe₃)₂}AgOClO₃ (7) ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti).The structures of 6a (M = Pd) and 6b (M = Pt) in the solid state are reported. In both complexes the d⁸-configurated transition metal ions palladium(II) and platinum(II) possess a somewhat distorted square-planar coordination sphere. Coordination number 4 at the group-10 metal atoms M is reached by the coordination of two ortho-substituents Me₂NCH₂, the NCN ipso-carbon atom and the bromide ligand. The NC group is para-positioned with respect to M.     

Syntheses and crystal structures of linear coordinated complexes of Ag with the ligands C(PPh3)2 and (HC{PPh3}2)

The cationic complexes [({Ph₃P}₂C)Ag(C{PPh₃}₂)]X (2⁺, X = Cl, BF₄) with a linear arrangement of the ligands were obtained from the reaction of C(PPh₃)₂ (1) with the appropriate AgX in THF. The ³¹P NMR spectrum of the cation 2⁺ exhibits a doublet with J(Ag,P) = 15.3 Hz. The cation was also formed when the adduct O₂C ← 1 was allowed to react with AgX in CH₂Cl₂ in the first step as shown by ³¹P NMR; however, deprotonation of the solvent finally produced the cation (HC{PPh₃}₂)⁺, (H1)⁺ quantitatively. In the absence of coordinating anions, the tricationic complex [({Ph₃P}₂CH)Ag(CH{PPh₃}₂)](BF₄)₃ (3), containing the cation (H1)⁺ as ligand, could be isolated by reacting AgBF₄ with the salt (H1)(BF₄). All compounds were characterized by IR and ³¹P NMR spectroscopy; the structures of the compounds [2]Cl·1.25THF, 3·5CH₂Cl₂, 3·4C₂H₄Cl₂, and (H1)(BF₄) could be established by X-ray analyses.     

Kinetics of the R + HBr RH + Br (CH3CHBr, CHBr2 or CDBr2) equilibrium. Thermochemistry of the CH3CHBr and CHBr2 radicals

The kinetics of the reaction of the CH₃CHBr, CHBr₂ or CDBr₂ radicals, R, with HBr have been investigated in a temperature-controlled tubular reactor coupled to a photoionization mass spectrometer. The CH₃CHBr (or CHBr₂ or CDBr₂) radical was produced homogeneously in the reactor by a pulsed 248 nm exciplex laser photolysis of CH₃CHBr₂ (or CHBr₃ or CDBr₃). The decay of R was monitored as a function of HBr concentration under pseudo-first-order conditions to determine the rate constants as a function of temperature. The reactions were studied separately from 253 to 344 K (CH₃CHBr + HBr) and from 288 to 477 K (CHBr₂ + HBr) and in these temperature ranges the rate constants determined were fitted to an Arrhenius expression (error limits stated are 1σ + Student’s t values, units in cm³ molecule⁻¹ s⁻¹, no error limits for the third reaction): k(CH₃CHBr + HBr) = (1.7 ± 1.2) × 10⁻¹³ exp[+ (5.1 ± 1.9) kJ mol⁻¹/RT], k(CHBr₂ + HBr) = (2.5 ± 1.2) × 10⁻¹³ exp[−(4.04 ± 1.14) kJ mol⁻¹/RT] and k(CDBr₂ + HBr) = 1.6 × 10⁻¹³ exp(−2.1 kJ mol⁻¹/RT). The energy barriers of the reverse reactions were taken from the literature. The enthalpy of formation values of the CH₃CHBr and CHBr₂ radicals and an experimental entropy value at 298 K for the CH₃CHBr radical were obtained using a second-law method. The result for the entropy value for the CH₃CHBr radical is 305 ± 9 J K⁻¹ mol⁻¹. The results for the enthalpy of formation values at 298 K are (in kJ mol⁻¹): 133.4 ± 3.4 (CH₃CHBr) and 199.1 ± 2.7 (CHBr₂), and for α-C–H bond dissociation energies of analogous compounds are (in kJ mol⁻¹): 415.0 ± 2.7 (CH₃CH₂Br) and 412.6 ± 2.7 (CH₂Br₂), respectively.