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Xie J Huang JS Zhu N Zhou ZY Che CM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(8):2405-2416
[Ru(II)(por)(PH(n)Ph(3-n))2], [Os(II)(por)(CO)(PH(n)Ph(3-n))] (n=1, 2), and [Os(II)(F20-tpp){P(OH)Ph2}(PHPh2)] (F20-tpp=5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato dianion) were prepared from the reaction of [M(II)(por)(CO)] (M=Ru, Os) or [Os(VI)(por)O2] with the respective primary/secondary phosphane and characterized by 1H NMR, 31P NMR, UV/Vis, and IR spectroscopy, mass spectrometry, and elemental analysis. The reaction of [Os(VI)(por)O2] with PHPh2 also gave minor amounts of [Os(II)(por){P(OH)Ph2}2]. [Ru(II)(F20-tpp)(PH2Ph)2] exhibits a remarkable stability toward air and shows a reversible metal-centered oxidation couple at E(1/2)=0.39 V versus [Cp2Fe](+/0) in the cyclic voltammogram. The structures of [Ru(II)(F20-tpp)(PH2Ph)2] x 2CH2Cl2, [Ru(II)(4-Cl-tpp)(PHPh2)2] x 2CH2Cl2 (4-Cl-tpp=5,10,15,20-tetrakis(p-chlorophenyl)porphyrinato dianion), [Ru(II)(F20-tpp)(PHPh2)2], and [Os(II)(F20-tpp){P(OH)Ph2}2] were determined by X-ray crystallography and feature Ru-P distances of 2.3397(11)-2.3609(9) A and an Os-P distance of 2.369(2) A. 相似文献
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Barbaro P Di Vaira M Peruzzini M Seniori Costantini S Stoppioni P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(23):6682-6690
The reaction of [CpRu(PPh(3))(2)Cl] (1) with half an equivalent of P(4) or P(4)S(3) in the presence of AgCF(3)SO(3) as chloride scavenger affords the stable dimetal complexes [{CpRu(PPh(3))(2)}(2)(micro,eta(1:1)-P(4))][CF(3)SO(3)](2).3 CH(2)Cl(2) (2) and [{CpRu(PPh(3))(2)}(2)(micro,eta(1:1)-P(apical)-P(basal)-P(4)S(3))][CF(3)SO(3)](2).0.5 C(7)H(8) (3), in which the tetrahedral P(4) and mixed-cage P(4)S(3) molecules are respectively bound to two CpRu(PPh(3))(2) fragments through two phosphorus atoms. The coordinated cage molecules, at variance with the free ligands, readily react with an excess of water in THF under mild conditions. Among the hydrolysis products, the new, remarkably stable complexes [{CpRu(PPh(3))(2)}(2)(micro,eta(1:1)-P(2)H(4))][CF(3)SO(3)](2) (4) and [CpRu(PPh(3))(2)(eta(1)-PH(2)SH)]CF(3)SO(3) (8) were isolated. In the former, diphosphane, P(2)H(4), is coordinated to two CpRu(PPh(3))(2) fragments, and in the latter thiophosphinous acid, H(2)PSH, is coordinated to the metal centre through the phosphorus atom. All compounds were characterised by elemental analyses and IR and NMR spectroscopy. The crystal structures of 2, 3, 4 and 8 were determined by X-ray diffraction. 相似文献
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Mas-Ballesté R Aullón G Champkin PA Clegg W Mégret C González-Duarte P Lledós A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(20):5023-5035
Given the nucleophilicity of the [Pt(2)S(2)] ring, the evolution of [Pt(2)(mu-S)(2)(P intersection P)(2)] (P intersection P=1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp)) metalloligands in the presence of the simplest electrophilic species, the proton, has been studied. Combined use of experimental and theoretical data has allowed the whole set of reactions ensuing the protonation of the [Pt(2)S(2)] core to be established. The titration of [Pt(2)(mu-S)(2)(P intersection P)(2)] with HCl or HClO(4) was monitored mainly by (31)P[(1)H] NMR and mass techniques. Characterization of all the species involved was completed with the determination of the crystal structure of [Pt(SH)(2)(P intersection P)], for dppe and dppp, and [Pt(3)(mu(3)-S)(2)(dppp)(3)](PF(6))(2). The first protonation step of the [Pt(2)S(2)] core leads to the stable [Pt(2)(mu-S)(mu-SH)(P intersection P)(2)](+) complex, but the second step implies disintegration of the ring, thus giving rise to various mononuclear species. The subsequent evolution of some of these species allows regeneration of [Pt(2)(mu-S)(mu-SH)(P intersection P)(2)](+), evidencing the cyclic nature of this process. Whereas the reaction pathway is essentially common for both phosphine ligands, dppe and dppp, the different coordinating ability of Cl(-) or ClO(4) (-) determines the nature of the final products, [PtCl(2)(P intersection P)], [Pt(3)(mu(3)-S)(2)(P intersection P)(3)]Cl(2) or [Pt(3)(mu(3)-S)(2)(P intersection P)(3)](ClO(4))(2). DFT calculations have corroborated the thermodynamic feasibility of the reactions proposed on the basis of experimental data. 相似文献
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The Challenge of Linear (E)‐Enones in the Rh‐Catalyzed,Asymmetric 1,4‐Addition Reaction of Phenylboronic Acid: A DFT Computational Analysis
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Prof. Hua‐Li Qin Xiao‐Qing Chen Zhen‐Peng Shang Prof. Eric Assen B. Kantchev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):3079-3086
Why are linear (E)‐enones such challenging substrates in the Rh‐catalyzed asymmetric arylation with boronic acids, which is one of the most important asymmetric catalysis methods? DFT computations show that these substrates adopt a specific conformation in which the largest substituent is antiperiplanar to RhI π‐complexed with the C?C bond within the enantioselectivity‐determining carborhodation transition state. Additionally, for such structures, there is a strong, but not exclusive, preference for s‐cis enone conformation. This folding minimizes steric interactions between the substrate and the ligand, and hence reduces the enantioselectivity. This idea is further confirmed by investigating three computation‐only substrate “probes”, one of which is capable of double asymmetric induction, and a recent computationally designed 1,5‐diene ligand. On average, excellent agreement between predicted and experimental enantioselectivity was attained by a three‐pronged approach: 1) thorough conformational search within ligand and substrate subunits to locate the most preferred carborhodation transition state; 2) including dispersion interaction and long‐range corrections by SMD/ωB97xD/DGDZVP level of theory; and 3) full substrate and ligand modeling. Based on the results, a theory‐enhanced enantioselectivity model that is applicable to both chiral diene and diphosphane ligands is proposed. 相似文献
7.
Schenk WA Beucke T Burzlaff N Klüglein M Stemmler M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(18):4821-4834
Ruthenium hydrogensulfido complexes [CpRu(P-P)(SH)] ((P-P)=Ph(2)PCH(2)PPh(2) (dppm), Ph(2)PC(2)H(4)PPh(2) (dppe)) were obtained from the corresponding chloro complexes by Cl/SH exchange. Condensation with a range of cinnamaldehydes gave thiocinnamaldehyde complexes [CpRu(P-P)(S=CH-CR(2)=CHR(1))]PF(6) (R(1)=C(6)H(4)X, R(2)=H, Me, X=H, OMe, NMe(2), Cl, NO(2)) as highly-colored crystalline compounds. The thiocinnamaldehyde complexes undergo [4+2]-cycloaddition reactions with vinyl ethers CH(2)=CHOR(3) (R(3)=Et, Bu) and styrenes H(2)C=CHC(6)H(4)Y (Y=H, Me, OMe, Cl, Br, NO(2)) to give complexes of 2,4,5-trisubstituted 3,4-dihydro-2H-thiopyrans as mixtures of two diastereoisomers. The rate of addition of para-substituted styrenes H(2)C=CHC(6)H(4)Y to [CpRu(dppm)(S=CH-CH=CHPh)]PF(6) increases in the series Y=NO(2), Br, Cl, H, Me, OMe, indicating that the cycloaddition is dominated by the HOMO(dienophile)-LUMO(diene) interaction. The strained dienophiles norbornadiene and norbornene also add, giving ruthenium complexes of 3-thia-tricyclo[6.2.1.0(2,7)]undeca-4,9-dienes and 3-thia-tricyclo[6.2.1.0(2,7)]undec-4-enes, respectively. Addition reactions with acrolein, methacrolein, methyl vinyl ketone, acrylic ester, or ethyl propiolate finally yielded ruthenium complexes of 3,4-disubstituted 3,4-dihydro-2H-thiopyrans and 4H-thiopyrans, respectively. 相似文献
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Trifonov AA Borovkov IA Fedorova EA Fukin GK Larionova J Druzhkov NO Cherkasov VK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(17):4981-4987
Ytterbocene [Yb(C(5)MeH(4))(2)(thf)(2)] reacts with diazabutadiene 2,6-iPr(2)C(6)H(3)-N=CH-CH=N-C(6)H(3)iPr(2)-2,6 (DAD) as a one-electron reductant to afford a bis(cyclopentadienyl) Yb(III) derivative containing a DAD radical anion [Yb(C(5)MeH(4))(2)(dad(-.))]. However, ytterbocenes [YbCp*(2)(thf)(2)] (Cp*=C(5)Me(5), C(5)Me(4)H) coordinated by sterically demanding cyclopentadienyl ligands act as two-electron reductants in their reactions with DAD. These reactions occur by abstraction of one Cp* ring and result in the formation of novel Yb(III) mixed-ligand bent-sandwich complexes, [YbCp*(dad)(thf)], in which the dianion of DAD has an uncommon terminal eta(4)-coordination to the ytterbium atom. The variable-temperature magnetic measurements of complex [Yb(C(5)Me(5))(dad)(thf)] suggest the existence of redox tautomerism for this compound. 相似文献
9.
Owen GR Stahl J Hampel F Gladysz JA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(1):73-87
Sequential reactions of trans-(C6F5)(p-tol3P)2Pt(C[triple chemical bond]C)3SiEt3 (PtC6SiEt3) with nBu4N+ F(-) (THF/methanol), PtCl, KPF6/tBuOK, and CuCl give trans,trans-[(C6F5){(p-tol3P)2}Pt(C[triple chemical bond]C)3Pt{(Pp-tol3)2}(C6F5)] (PtC6Pt) in 95 % yield on multigram scales. Reactions of PtC6Pt and Ar2P(CH2)mPAr2 afford substitution products trans,trans-[(C6F5){(Ar2P(CH2)mPAr2)}Pt(C[triple chemical bond]C)3Pt{(Ar2P(CH2)mPAr2)}(C6F5)] (PtC6Pt-m/Ar; m/Ar=8/p-tol, 78 %; 10/Ph, 82 %; 11/Ph, 69 %; 12/Ph, 57 %; 14/p-tol, 57 %; 14/p-C6H4-tBu, 71 %), in which the diphosphines span the square planar platinum endgroups. An analogous reaction with PEt3 gives a tetrakis PEt3 complex Pt'C6Pt' (72 %). The crystal structures of PtC6Pt, Pt'C6Pt', PtC6Pt-10/Ph, PtC6Pt-11/Ph, and PtC6Pt-14/p-tol or solvates thereof are compared. In PtC6Pt, the endgroups can avoid van der Waals contact, and define angles of 0 degrees . In PtC6Pt-14/p-tol, the sp3 chains twist around the sp chain in a chiral double-helical motif, with an endgroup/endgroup angle of 189 degrees . The sp3 chains are too short to adopt analogous conformations in the other complexes, but laterally shield the sp chain. NMR spectroscopy shows that the helical enantiomers of PtC6Pt-14/p-tol rapidly interconvert in solution at low temperature. A crystal structure of PtC4Pt shows endgroups that are in van der Waals contact and define an angle of 41 degrees . Reactions with Ar2P(CH2)8PAr2 give PtC4Pt-8/Ar (Ar=Ph, 53 %; p-tol, 87 %). Low-temperature NMR spectroscopy establish non-helical chiral conformations. Electrochemical oxidations of the diplatinum complexes are analyzed, the reversibilities of which decrease with increasing sp chain length. 相似文献
10.
Zheng Q Bohling JC Peters TB Frisch AC Hampel F Gladysz JA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(25):6486-6505
The reaction of trans-[PtCl(p-tol){P(p-tol)3}2] (PtCl) and H(C[triple chemical bond]C)2H (cat. CuI, HNEt2) gives PtC4H (82 %), which can be cross-coupled with excess HC[triple chemical bond]CSiEt3 (acetone, O2, CuCl/TMEDA; Hay conditions) to yield PtC6Si (77 %). The addition of nBu4N+F- in wet acetone gives PtC6H (84 %), and further addition of ClSiMe3 (F- scavenger) and excess HC[triple chemical bond]CSiEt3 (Hay conditions) yields PtC(8)Si (23 %). Similar cross-coupling reactions of PtCxH (generated in situ for x>6) and excess H(C[triple chemical bond]C)2SiEt3 give a) x=4, PtC8Si (29 %), PtC12Si (30 %), and PtC16Si (1 %); b) x=6, PtC10Si (59 %) and PtC14Si (7 %); c) x=8, PtC12Si (42 %); and d) x=10, PtC14Si (20 %). Hay homocoupling reactions of PtC4H, PtC6H, PtC8H, and PtC10H give PtC8Pt, PtC12Pt, PtC16Pt, and PtC20Pt (88-70 %), but PtC12H decomposes too rapidly. However, when PtC12Si and PtC14Si are subjected to Hay conditions, protodesilylation occurs in the presence of the oxidizing agent and PtC24Pt (36 %) and PtC28Pt (51 %) are isolated. Reactions of PtC6H and PtC10H with PtCl (CuI, HNEt2) give PtC6Pt (56 %) and PtC10Pt (84 %). The effect of the chain lengths in PtCxPt upon thermal stabilities (>200 degrees C for x< or =20), IR nu(C[triple chemical bond]C) patterns (progressively more bands), colors (yellow to orange to deep red), UV/Vis spectra (progressively red-shifted and more intense bands with epsilon>400,000 M(-1) cm(-1)), redox properties (progressively more difficult oxidations), and NMR spectra (many monotonic trends) are analyzed, including implications for the sp carbon allotrope carbyne. Whereas all other dodecaynes and tetradecaynes rapidly decompose at room temperature, PtC24Pt and PtC28Pt remain stable at >140 degrees C. Crystal structures of PtCxSi (x=6, 8, 10) and PtCxPt (x=6, 8, 10, 12) have been determined. 相似文献
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Roesky PW Gamer MT Marinos N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(14):3537-3542
Treatment of the recently reported potassium salt [K(thf)(n)][N(PPh(2))(2)] (n=1.25, 1.5) with anhydrous yttrium or lanthanide trichlorides in THF leads after crystallization from THF/n-pentane (1:2) to the monosubstituted diphosphanylamide complexes [LnCl(2)[(Ph(2)P)(2)N](thf)(3)] (Ln=Y, Sm, Er, Yb). The single-crystal X-ray structures of these complexes show that the metal atoms are surrounded by seven ligands in a distorted pentagonal bipyramidal arrangement, in which the chlorine atoms are located in the apical positions. The diphosphanylamide ligand is always eta(2)-coordinated through the nitrogen atom and one phosphorus atom. Further reaction of [SmCl(2)[(Ph(2)P)(2)N](thf)(3)] with K(2)C(8)H(8) or reaction of [LnI(eta(8)-C(8)H(8))(thf)(3)] with [K(thf)(n)][N(PPh(2))(2)] in THF gives the corresponding cyclooctatetraene complexes [Ln[(Ph(2)P)(2)N](eta(8)-C(8)H(8))(thf)(2)] (Ln=La, Sm). The single crystals of these compounds contain enantiomerically pure complexes. Both compounds adopt a four-legged piano-stool conformation in the solid state. The structures of the A and the C enantiomers were established by single-crystal X-ray diffraction. The more soluble bistrimethylsilyl cyclooctatetraene complex [Y[(Ph(2)P)(2)N](eta(8)-1,4-(Me(3)Si)(2)C(8)H(6))(thf)(2)] was obtained by transmetallation of Li(2)[1,4-(Me(3)Si)(2)C(8)H(6)] with anhydrous yttrium trichloride in THF followed by the addition of one equivalent of [K(thf)(n)][N(PPh(2))(2)]. The (89)Y NMR signal of the complex is split up into a triplet, supporting other observations that the phosphorus atoms are chemically equivalent in solution and, thus, dynamic behavior of the ligand in solution can be anticipated. 相似文献
12.
Organosilicon backbone containing ligands 1,2-bis(dimethyl(2-pyridyl)silyl)ethane (L1) and 1,2-bis(dimethyl(3-quinolyl)silyl) ethane (L2) have been synthesized by treating 2-bromopyridine and 3-bromoquinoline with n-butyllithium and reacting the resulting lithiated products with 1,2-bis(chlorodimethylsilyl)ethane. The ligation of L1 and L2 with Pd(II), Ag(I) and Cu(II) has been investigated. The single crystal structures of L2, [Pd(L1)Cl2] (1), [Cu(L1)Br2] (3) and [PdCl2(L2)]2 (4) have been solved. All the three complexes are metallamacrocyclic in nature. The last one is 22-membered and the first example which has ligands containing organosilicon backbone. The geometry of Pd as well as Cu is very close to square planar. The Pd–N, Pd–Cl, Cu–N and Cu–Br bond distances (2.010(1)–2.027(3), 2.3063(10)–2.3114(4), 2.004(4)–2.018(5) and 2.4137(10)–2.4172(10) Å) are very close to sum of covalent radii, indicating strong ligation of L1 and L2 with the metal ions. 相似文献
13.
Snelders DJ van Koten G Klein Gebbink RJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(1):42-57
The effects of introducing ionic functionalities in phosphine ligands on the coordination chemistry of these ligands and the catalytic behavior of the corresponding metal complexes are reviewed. The steric and electronic consequences of such functionalizations are discussed. Apart from these steric and electronic effects, the presence of charged groups often leads to additional, supramolecular interactions that occur in the second coordination sphere of the metal complex, such as intramolecular, interligand hydrogen bonding and Coulombic repulsion. These interactions can significantly alter the behavior of the phosphine ligand in question. Such effects have been observed in phosphine-metal association/dissociation equilibria, ligand substitution reactions, and stereoisomerism in phosphine-metal complexes. By drawing general conclusions, this review offers an insight into the coordination and catalytic behavior of phosphine ligands containing ionic functionalities and their corresponding metal complexes. 相似文献
14.
To study the structures and reactivities of alkali metallated intermediates of calix[4]arenes, three compounds were isolated: [Li(4)(p-tert-butylcalix[4]arene-4H)(thf)(4)](2).6 THF (1), [Li(2)(p-tert-butylcalix[4]arene-2H)(H(2)O)(mu-H(2)O)(thf)].3 THF (2), and [K(4)(p-tert-butylcalix[4]arene-4H)(thf)(5)](2).THF (3). The structure of 1 is shown to be dependent on the coordinating solvent. Partial hydrolysis of 1 leads to the formation of 2. The potassium compound 3 features a different structure to that of 1, due to a higher coordination number as well as stronger cation-pi-bonding interactions. 相似文献
15.
The structure elucidation of a new zinc phosphate [Co(II)(en)(3)][Zn(4)(H(2)PO(4))(3)(HPO(4))(2)(PO(4))(2 H(2)O)(2)] (1) reveals that the racemic cobalt complex templates the zinc phosphate framework in such a way that the local C(2) point symmetry of the structural motif of the inorganic framework conforms with that of the cobalt complex pairing with it, in essence transferring its chirality to the inorganic host. An analysis of hydrogen bonding between the guest molecules and the inorganic host framework reveals that hydrogen bonding is responsible for the stereospecific structural arrangement. Upon examining previously reported chiral metal-complex-templated structures of metal phosphates, it is revealed that such hydrogen bonding is the common origin for inducing chirality transfer in metal-phosphate frameworks templated with chiral metal complexes. Crystal data of 1: orthorhombic, Pbcn (no. 60), a=10.4787(8) A, b=20.0091(14) A, c=14.9594(10) A, and Z=2. 相似文献
16.
Christina Dietz Jana Martincová Bernard Mahieu Roman Jambor Sonja Herres‐Pawlis Klaus Jurkschat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(21):6695-6708
The syntheses of the transition metal complexes cis‐[(4‐tBu‐2,6‐{P(O)(OiPr)2}2C6H2SnCl)2MX2] ( 1 , M=Pd, X=Cl; 2 , M=Pd, X=Br; 3 , M=Pd, X=I; 4 , M=Pt, X=Cl), cis‐[{2,6‐(Me2NCH2)2C6H3SnCl}2MX2] ( 5 , M=Pd, X=I; 6 , M=Pt, X=Cl), trans‐[{2,6‐(Me2NCH2)2C6H3SnI}2PtI2] ( 7 ) and trans‐[(4‐tBu‐2,6‐{P(O)(OiPr)2}2 C6H2SnCl)PdI2]2 ( 8 ) are reported. Also reported is the serendipitous formation of the unprecedented complexes trans‐[(4‐tBu‐2,6‐{P(O)(OiPr)2}2C6H2SnCl)2 Pt(SnCl3)2] ( 10 ) and [(4‐tBu‐2,6‐{P(O) (OiPr)2}2C6H2SnCl)3Pt(SnCl3)2] ( 11 ). The compounds were characterised by elemental analyses, 1H, 13C, 31P, 119Sn and 195Pt NMR spectroscopy, single‐crystal X‐ray diffraction analysis, UV/Vis spectroscopy and, in the cases of compounds 1 , 3 and 4 , also by Mössbauer spectroscopy. All the compounds show the tin atoms in a distorted trigonal‐bipyramidal environment. The Mössbauer spectra suggest the tin atoms to be present in the oxidation state III. The kinetic lability of the complexes was studied by redistribution reactions between compounds 1 and 3 as well as between 1 and cis‐[{2,6‐(Me2NCH2)2C6H3SnCl}2PdCl2]. DFT calculations provided insights into both the bonding situation of the compounds and the energy difference between the cis and trans isomers. The latter is influenced by the donor strength of the pincer‐type ligands. 相似文献
17.
Algarra AG Basallote MG Feliz M Fernández-Trujillo MJ Llusar R Safont VS 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(5):1413-1426
The reaction of the hydride cluster [W3S4H3(dmpe)3]+ (1, dmpe = 1,2-bis(dimethylphosphanyl)ethane) with acids (HCl, CF3COOH, HBF4) in CH2Cl2 solution under pseudo-first-order conditions of excess acid occurs with three kinetically distinguishable steps that can be interpreted as corresponding to successive formal substitution processes of the coordinated hydrides by the anion of the acid (HCl, CF3COOH) or the solvent (HBF4). Whereas the rate law for the third step changes with the nature of the acid, the first two kinetic steps always show a second-order dependence on acid concentration. In contrast, a single kinetic step with a first-order dependence with respect to the acid is observed when the experiments are carried out with a deficit of acid. The decrease in the T1 values for the hydride NMR signal of 1 in the presence of added HCl suggests the formation of an adduct with a W-H...H-Cl dihydrogen bond. Theoretical calculations for the reaction with HCl indicate that the kinetic results in CH2Cl2 solution can be interpreted on the basis of a mechanism with two competitive pathways. One of the pathways consists of direct proton transfer within the W-H...H-Cl adduct to form W-Cl and H2, whereas the other requires the presence of a second HCl molecule to form a W-H...H-Cl...H-Cl adduct that transforms into W-Cl, H2 and HCl in the rate-determining step. The activation barriers and the structures of the transition states for both pathways were also calculated, and the results indicate that both pathways can be competitive and that the transition states can be described in both cases as a dihydrogen complex hydrogen-bonded to Cl- or HCl2(-). 相似文献
18.
Aresta M Dibenedetto A Pápai I Schubert G Macchioni A Zuccaccia D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(15):3708-3716
The synthesis, characterization and properties of [PdH(dppe)(2)](+)CF(3)SO(3) (-).0.125 THF (1; dppe=1,2-bis(diphenylphosphanyl)ethane) and its SbF(6) (-) (1') and BF(4) (-) (1") analogues, the missing members of the [MH(dppe)(2)](+)X(-) (M=Ni, Pd, Pt) family, are described. The Pd hydrides are not stable in solution and can react as proton or hydride donors with formation of dihydrogen, [Pd(dppe)(2)](2+) and [Pd(dppe)(2)]. Complexes 1-1" react with carbocations and carbanions by transferring a hydride and a proton, respectively. Such H(-) or H(+) transfer occurs also towards unsaturated compounds, for example, hydrogenation of a C=C double bond. Accordingly, 1 can hydrogenate methyl acrylate to methyl propionate. Complex 1" is an effective (hourly turnover frequency=16) and very selective (100 %) catalyst for the hydrogenation of cyclohexen-2-one to cyclohexanone with dihydrogen under mild conditions. Density functional calculations coupled with a dielectric continuum model were carried out to compute the energetics of the hydride/proton transfer reactions, which were used to rationalize some of the experimental findings. Theory provides strong support for the thermodynamic and kinetic viability of a tetracoordinate Pd complex as an intermediate in the reactions. 相似文献
19.
Petr Štěpni?ka Hana Sola?ová Ivana Císa?ová 《Journal of organometallic chemistry》2011,696(23):3727-3740
Two polar phosphinoferrocene ligands, 1′-(diphenylphosphino)ferrocene-1-carboxamide (1) and 1′-(diphenylphosphino)ferrocene-1-carbohydrazide (2), were synthesized in good yields from 1′-(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) via the reactive benzotriazole derivative, 1-[1′-(diphenylphosphino)ferrocene-1-carbonyl]-1H-1,2,3-benzotriazole (3). Alternatively, the hydrazide was prepared by the conventional reaction of methyl 1′-(diphenylphosphino)ferrocene-1-carboxylate with hydrazine hydrate, and was further converted via standard condensation reactions to three phosphinoferrocene heterocycles, viz 2-[1′-(diphenylphosphino)ferrocen-1-yl]-1,3,4-oxadiazole (4), 1-[1′-(diphenylphosphino)ferrocen-1-carbonyl]-3,5-dimethyl-1,2-pyrazole (5), and 1-[1′-(diphenylphosphino)ferrocene-1-carboxamido]-3,5-dimethylpyrrole (6). Compounds 1 and 2 react with [PdCl2(cod)] (cod = η2:η2-cycloocta-1,5-diene) to afford the respective bis-phosphine complexes trans-[PdCl2(L-κP)2] (7, L = 1; 8, L = 2). The dimeric precursor [(LNC)PdCl]2 (LNC = 2-[(dimethylamino-κN)methyl]phenyl-κC1) is cleaved with 1 to give the neutral phosphine complex [(LNC)PdCl(1-κP)] (9), which is readily transformed into a ionic bis-chelate complex [(LNC)PdCl(1-κ2O,P)][SbF6] (10) upon removal of the chloride ligand with Ag[SbF6]. Pyrazole 5 behaves similarly affording the related complexes [(LNC)PdCl(5-κP)] (12) and [(LNC)PdCl(5-κ2O,P)][SbF6] (13), in which the ferrocene ligand coordinates as a simple phosphine and an O,P-chelate respectively, while oxadiazole 4 affords the phosphine complex [(LNC)PdCl(4-κP)] (11) and a P,N-chelate [(LNC)PdCl(4-κ2N3,P)][SbF6] (14) under similar conditions. All compounds were characterized by elemental analysis and spectroscopic methods (multinuclear NMR, IR and MS). The solid-state structures of 1⋅½AcOEt, 2, 7⋅3CH3CN, 8⋅2CHCl3, 9⋅½CH2Cl2⋅0.375C6H14, 10, and 14 were determined by single-crystal X-ray crystallography. 相似文献
20.
Yang YL Lu CP Chen MY Chen KY Wu YC Wu SH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(24):6985-6991
Five new polyketides that contain tetramic acids, myceliothermophins A-E, were isolated from the thermophilic fungus Myceliophthora thermophila. Two sets of 5-alkyl-5-hydroxyl (or 5-methoxyl)-1H-pyrrol-2(5H)-one diastereomers, myceliothermophins A/B and C/D, were separated as pure compounds by using silica-gel column chromatography and recycling reverse-phase high-performance liquid chromatography (RP-HPLC). The relative configurations of the chiral centers in 5-alkyl-5-hydroxyl (or 5-methoxyl)-1H-pyrrol-2(5H)-one moieties were deduced from NOESY correlations. In the cytotoxic assay, the 5-(2-methylpropyldiene)-1H-pyrrol-2(5H)-one analogue (myceliothermophin E) exhibited inhibition against four cancer cell lines. In addition, the significant inhibitory effect of myceliothermophins A and C and the inactivity of myceliothermophins B and D revealed the importance of the relative configurations of 5-alkyl-5-hydroxyl (or 5-methoxyl)-1H-pyrrol-2(5H)-one moieties on their cytotoxicity potency against cancer cells. 相似文献