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1.
《Angewandte Chemie (International ed. in English)》2017,56(10):2720-2724
N‐Heterocyclic carbene based pincer ligands bearing a central silyl donor, [CSiC]−, have been envisioned as a class of strongly σ‐donating ligands that can be used for synthesizing electron‐rich transition‐metal complexes for the activation of inert bonds. However, this type of pincer ligand and complexes thereof have remained elusive owing to their challenging synthesis. We herein describe the first synthesis of a CSiC pincer ligand scaffold through the coupling of a silyl–NHC chelate with a benzyl–NHC chelate induced by one‐electron oxidation in the coordination sphere of a cobalt complex. The monoanionic CSiC ligand stabilizes the CoI dinitrogen complex [(CSiC)Co(N2)] with an unusual coordination geometry and enables the challenging oxidative addition of E−H bonds (E=C, N, O) to CoI to form CoIII complexes. The structure and reactivity of the cobalt(I) complex are ascribed to the unique electronic properties of the CSiC pincer ligand, which provides a strong trans effect and pronounced σ‐donation. 相似文献
2.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(10):2764-2768
N‐Heterocyclic carbene based pincer ligands bearing a central silyl donor, [CSiC]−, have been envisioned as a class of strongly σ‐donating ligands that can be used for synthesizing electron‐rich transition‐metal complexes for the activation of inert bonds. However, this type of pincer ligand and complexes thereof have remained elusive owing to their challenging synthesis. We herein describe the first synthesis of a CSiC pincer ligand scaffold through the coupling of a silyl–NHC chelate with a benzyl–NHC chelate induced by one‐electron oxidation in the coordination sphere of a cobalt complex. The monoanionic CSiC ligand stabilizes the CoI dinitrogen complex [(CSiC)Co(N2)] with an unusual coordination geometry and enables the challenging oxidative addition of E−H bonds (E=C, N, O) to CoI to form CoIII complexes. The structure and reactivity of the cobalt(I) complex are ascribed to the unique electronic properties of the CSiC pincer ligand, which provides a strong trans effect and pronounced σ‐donation. 相似文献
3.
Taichi Abe Kazuteru Shinozaki Noriaki Ikeda Takayoshi Suzuki 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):m456-m458
In the title compound, [Pt(C18H15N2)Cl], the PtII centre adopts a distorted square‐planar coordination geometry due to the pincer‐type monoanionic N–C–N tridentate ligand. The planar complexes stack viaπ–π interactions to form two‐dimensional accumulated sheets. This packing pattern is in contrast to that in related pincer‐type N–C–N complexes, which exhibit a one‐dimensional columnar stacking. 相似文献
4.
Four NHC [CNN] pincer nickel (II) complexes, [iPrCNN (CH2)4‐Ni‐Br] ( 5a ), [nBuCNN (CH2)4‐Ni‐Br] ( 5b ), [iPrCNN (Me)2‐Ni‐Br] ( 6a ) and [nBuCNN (Me)2‐Ni‐Br] ( 6b ), bearing unsymmetrical [C (carbene)N (amino)N (amine)] ligands were synthesized by the reactions of [CNN] pincer ligand precursors 4 with Ni (DME)Cl2 in the presence of Et3N. Complexes 5a and 5b are new and were completely characterized. The transfer hydrogenation of ketones catalyzed by the four pincer nickel complexes were explored. Complexes 5a and 6a have better catalytic activity than 5b and 6b . With a combination of NaOtBu/iPrOH/80 °C and 2% catalyst loading of 5a , 77–98% yields of aromatic alcohols could be obtained. 相似文献
5.
Ruthenium(II) Complexes Containing Lutidine‐Derived Pincer CNC Ligands: Synthesis,Structure, and Catalytic Hydrogenation of CN bonds
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Dr. Martín Hernández‐Juárez Dr. Joaquín López‐Serrano Dr. Patricia Lara Judith P. Morales‐Cerón Dr. Mónica Vaquero Dr. Eleuterio Álvarez Prof. Verónica Salazar Dr. Andrés Suárez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7540-7555
A series of Ru complexes containing lutidine‐derived pincer CNC ligands have been prepared by transmetalation with the corresponding silver‐carbene derivatives. Characterization of these derivatives shows both mer and fac coordination of the CNC ligands depending on the wingtips of the N‐heterocyclic carbene fragments. In the presence of tBuOK, the Ru‐CNC complexes are active in the hydrogenation of a series of imines. In addition, these complexes catalyze the reversible hydrogenation of phenantridine. Detailed NMR spectroscopic studies have shown the capability of the CNC ligand to be deprotonated and get involved in ligand‐assisted activation of dihydrogen. More interestingly, upon deprotonation, the Ru‐CNC complex 5 e (BF4) is able to add aldimines to the metal–ligand framework to yield an amido complex. Finally, investigation of the mechanism of the hydrogenation of imines has been carried out by means of DFT calculations. The calculated mechanism involves outer‐sphere stepwise hydrogen transfer to the C?N bond assisted either by the pincer ligand or a second coordinated H2 molecule. 相似文献
6.
Marco A. García-Eleno Magdalena Quezada-Miriel Reyna Reyes-Martínez Simn Hernndez-Ortega David Morales-Morales 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(5):393-397
Pincer complexes can act as catalysts in organic transformations and have potential applications in materials, medicine and biology. They exhibit robust structures and high thermal stability attributed to the tridentate coordination of the pincer ligands and the strong σ metal–carbon bond. Nickel derivatives of these ligands have shown high catalytic activities in cross‐coupling reactions and other industrially relevant transformations. This work reports the crystal structures of two polymorphs of the title NiII POCOP pincer complex, [Ni(C29H41N2O8P2)Cl] or [NiCl{C6H2‐4‐[OCOC6H4‐3,5‐(NO2)2]‐2,6‐(OPtBu2)2}]. Both pincer structures exhibit the NiII atom in a distorted square‐planar coordination geometry with the POCOP pincer ligand coordinated in a typical tridentate manner via the two P atoms and one arene C atom via a C—Ni σ bond, giving rise to two five‐membered chelate rings. The coordination sphere of the NiII centre is completed by a chloride ligand. The asymmetric units of both polymorphs consist of one molecule of the pincer complex. In the first polymorph, the arene rings are nearly coplanar, with a dihedral angle between the mean planes of 27.9 (1)°, while in the second polymorph, this angle is 82.64 (1)°, which shows that the arene rings are almost perpendicular to one another. The supramolecular structure is directed by the presence of weak C—H…O=X (X = C or N) interactions, forming two‐ and three‐dimensional chain arrangements. 相似文献
7.
Square‐Planar Ruthenium(II) Complexes: Control of Spin State by Pincer Ligand Functionalization
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Dr. Bjorn Askevold Dr. Marat M. Khusniyarov Dr. Wolfgang Kroener Dr. Klaus Gieb Prof. Paul Müller Dr. Eberhardt Herdtweck Dr. Frank W. Heinemann Dr. Martin Diefenbach Prof. Max C. Holthausen Veacheslav Vieru Prof. Liviu F. Chibotaru Prof. Sven Schneider 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):579-589
Functionalization of the PNP pincer ligand backbone allows for a comparison of the dialkyl amido, vinyl alkyl amido, and divinyl amido ruthenium(II) pincer complex series [RuCl{N(CH2CH2PtBu2)2}], [RuCl{N(CHCHPtBu2)(CH2CH2PtBu2)}], and [RuCl{N(CHCHPtBu2)2}], in which the ruthenium(II) ions are in the extremely rare square‐planar coordination geometry. Whereas the dialkylamido complex adopts an electronic singlet (S=0) ground state and energetically low‐lying triplet (S=1) state, the vinyl alkyl amido and the divinyl amido complexes exhibit unusual triplet (S=1) ground states as confirmed by experimental and computational examination. However, essentially non‐magnetic ground states arise for the two intermediate‐spin complexes owing to unusually large zero‐field splitting (D>+200 cm?1). The change in ground state electronic configuration is attributed to tailored pincer ligand‐to‐metal π‐donation within the PNP ligand series. 相似文献
8.
Pincer‐Type Platinum(II) Complexes Containing N‐Heterocyclic Carbene (NHC) Ligand: Structures,Photophysical and Anion‐Binding Properties,and Anticancer Activities
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Dr. Kai Li Dr. Taotao Zou Prof. Dr. Yong Chen Dr. Xiangguo Guan Prof. Dr. Chi‐Ming Che 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7441-7453
Two classes of pincer‐type PtII complexes containing tridentate N‐donor ligands ( 1 – 8 ) or C‐deprotonated N^C^N ligands derived from 1,3‐di(2‐pyridyl)benzene ( 10 – 13 ) and auxiliary N‐heterocyclic carbene (NHC) ligand were synthesized. [Pt(trpy)(NHC)]2+ complexes 1 – 5 display green phosphorescence in CH2Cl2 (Φ: 1.1–5.3 %; τ: 0.3–1.0 μs) at room temperature. Moderate‐to‐intense emissions are observed for 1 – 7 in glassy solutions at 77 K and for 1 – 6 in the solid state. The [Pt(N^C^N)(NHC)]+ complexes 10 – 13 display strong green phosphorescence with quantum yields up to 65 % in CHCl3. The reactions of 1 with a wide variety of anions were examined in various solvents. The tridentate N‐donor ligand of 1 undergoes displacement reaction with CN? in protic solvents. Similar displacement of the N^C^N ligand by CN? has been observed for 10 , leading to a luminescence “switch‐off” response. The water‐soluble 7 containing anthracenyl‐functionalized NHC ligand acts as a light “switch‐on” sensor for the detection of CN? ion with high selectivity. The in vitro cytotoxicity of the PtII complexes towards HeLa cells has been evaluated. Complex 12 showed high cytotoxicity with IC50 value of 0.46 μM , whereas 1 – 4 and 6 – 8 are less cytotoxic. The cellular localization of the strongly luminescent complex 12 traced by using emission microscopy revealed that it mainly localizes in the cytoplasmic structures rather than in the nucleus. This complex can induce mitochondria dysfunction and subsequent cell death. 相似文献
9.
Douglas R. Hartline Dr. Matthias Zeller Prof. Christopher Uyeda 《Angewandte Chemie (International ed. in English)》2016,55(20):6084-6087
The mechanism of the Pauson–Khand reaction has attracted significant interest due to the unusual dinuclear nature of the Co2(CO)x active site. Experimental and computational data have indicated that the intermediates following the initial Co2(CO)6(alkyne) complex are thermodynamically unstable and do not build up in appreciable concentrations during the course of the reaction. As a consequence, the key steps that control the scope of viable substrates and various aspects of selectivity have remained largely uncharacterized. Herein, a direct experimental investigation of the dinuclear metallacycle‐forming step of the Pauson–Khand reaction is reported. These studies capitalize on well‐defined d9–d9 dinickel complexes supported by a naphthyridine–diimine (NDI) pincer ligand as functional surrogates of Co2(CO)8. 相似文献
10.
Hydrogen Release from Dialkylamine–Boranes Promoted by Mg and Ca Complexes: A DFT Analysis of the Reaction Mechanism
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Dr. Valeria Butera Prof. Nino Russo Prof. Dr. Emilia Sicilia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(20):5967-5976
Mg and Ca β‐diketiminato silylamides [HC{(Me)CN(2,6‐iPr2C6H3)}2M(THF)n{N(SiMe3)2}] (M=Mg, n=0; M=Ca, n=1) were studied as precatalysts for the dehydrogenation/dehydrocoupling of secondary amine–boranes R2HNBH3. By reaction with equimolar quantities of amine–boranes, the corresponding amidoborane derivatives are formed, which further react to yield dehydrogenation products such as the cyclic dimer [BH2?NMe2]2. DFT was used here to explore the mechanistic alternatives proposed on the basis of the experimental findings for both Mg and Ca amidoboranes. The influence of the steric demand of amine–boranes on the course of the reaction was examined by performing calculations on the dehydrogenation of dimethylamine–borane (DMAB), pyrrolidine–borane (PB), and diisopropylamine–borane. In spite of the analogies in the catalytic activity of Mg‐ and Ca‐based complexes in the dehydrocoupling of amine–boranes, our theoretical analysis confirmed the experimentally observed lower reactivity of Ca complexes. Differences in catalytic activity of Mg‐ and Ca‐based complexes were examined and rationalized. As a consequence of the increase in ionic radius on going from Mg2+ to Ca2+, the dehydrogenation mechanism changes and formation of a key metal hydride intermediate becomes inaccessible. Dimerization is likely to occur off‐metal in solution for DMAB and PB, whereas steric hindrance of iPr2NHBH3 hampers formation of the cyclic dimer. The reported results are of particular interest because, although amine–borane dehydrogenation is now well established, mechanistic insight is still lacking for many systems. 相似文献
11.
Totally sixteen new titanium and zirconium non-Cp complexes supported by Schiff-base, or thiophene diamide ligands have been synthesized. The complexes are obtained by the reaction of M(OPr-i)4(M=Ti,Zr) with the corresponding Schiff-base ligand in 1:1 molar ratio in good yield. The thiophene diamide titanium complex has been prepared from trimethylsilyl amine [N,S,N] ligand and TiCl4 in toluene at 120℃. All complexes are well charac-terized by ^1H NMR, IR, MS and elemental analysis. When activated by excess methylaluminoxane (MAO), complexes show moderate catalytic activity for ethylene polymerization, and complex If (R^1=CH3,R^2=Br) exhibits the highest activity for ethylene and styrene polymerization. When the complexes were preactivated by triethylaluminum (TEA), both polymerization activities and syndiotacticity of the polymers were greatly improved. 相似文献
12.
Rhodium PCcarbeneP complexes 1‐L {L=PPh3, PPh2(C6F5)} react with isothiocyanate, carbodiimide and disulphide to enable C?S, C?N and S?S bond cleavage. The cleaved molecules are sequestered by the metal center and the pincer alkylidene linkage, forming η2‐coordinated sulfide or imide centered pincer complexes. When a C?S or S?S bond is cleaved, the resulting complexes can bridge two rhodium centers through sulphur forming dimeric complexes and eliminating a monodentate phosphine ligand. 相似文献
13.
Paul V. Bernhardt 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):744-746
The title pendent‐arm macrocyclic hexaamine ligand binds stereospecifically in a hexadentate manner, and we report here its isomorphous NiII and ZnII complexes (both as perchlorate salts), namely (cis‐6,13‐dimethyl‐1,4,8,11‐tetraazacyclotetradecane‐6,13‐diamine‐κ6N)nickel(II) diperchlorate, [Ni(C12H30N6)](ClO4)2, and (cis‐6,13‐dimethyl‐1,4,8,11‐tetraaza‐cyclotetradecane‐6,13‐diamine‐κ6N)zinc(II) diperchlorate, [Zn(C12H30N6)](ClO4)2. Distortion of the N—M—N valence angles from their ideal octahedral values becomes more pronounced with increasing metal‐ion size and the present results are compared with other structures of this ligand. 相似文献
14.
Kyung‐Sun Son Robert M. Waymouth 《Journal of polymer science. Part A, Polymer chemistry》2010,48(7):1579-1585
A series of monocyclopentadienyl titanium complexes containing a pendant amine donor on a Cp group ( A = CpTiCl3, B = CpNTiCl3, C = CpNTiCl2TEMPO, for Cp = C5H5, CpN = C5H4CH2CH2N(CH3)2, and TEMPO = 2,2,6,6‐tetramethylpiperidine‐N‐oxyl) are investigated for styrene homopolymerization and ethylene–styrene (ES) copolymerization. When activated by methylaluminoxane at 70 °C, complexes with the amine group ( B and C ) are active for styrene homopolymerization and afford syndiotactic polystyrene (sPS). The copolymerizations of ethylene and styrene with B and C yield high‐molecular weight ES copolymer, whereas complex A yields mixtures of sPS and polyethylene, revealing the critical role that the pendant amine has on the polymerization behavior of the complexes. Fractionation, NMR, and DSC analyses of the ES copolymers generated from B and C suggest that they contain sPS. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1579–1585, 2010 相似文献
15.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(7):569-574
The structure of a pincer ligand consists of a backbone and two `arms' which typically contain a P or N atom. They are tridentate ligands that coordinate to a metal center in a meridional configuration. A series of three iron complexes containing the pyrrole‐based PNP pincer ligand 2,5‐bis[(diisopropylphosphanyl)methyl]pyrrolide (PNpyrP) has been synthesized. These complexes are possible precursors to new iron catalysts. {2,5‐Bis[(diisopropylphosphanyl)methyl]pyrrolido‐κ3P ,N ,P ′}carbonylchlorido(trimethylphosphane‐κP )iron(II), [Fe(C18H34NP2)Cl(C3H9P)(CO)] or [Fe(PNpyrP)Cl(PMe3)(CO)], (I), has a slightly distorted octahedral geometry, with the Cl and CO ligands occupying the apical positions. {2,5‐Bis[(diisopropylphosphanyl)methyl]pyrrolido‐κ3P ,N ,P ′}chlorido(pyridine‐κN )iron(II), [Fe(C18H34NP2)Cl(C5H5N)] or [Fe(PNpyrP)Cl(py)] (py is pyridine), (II), is a five‐coordinate square‐pyramidal complex, with the pyridine ligand in the apical position. {2,5‐Bis[(diisopropylphosphanyl)methyl]pyrrolido‐κ3P ,N ,P ′}dicarbonylchloridoiron(II), [Fe(C18H34NP2)Cl(CO)2] or [Fe(PNpyrP)Cl(CO)2], (III), is structurally similar to (I), but with the PMe3 ligand replaced by a second carbonyl ligand from the reaction of (II) with CO. The two carbonyl ligands are in a cis configuration, and there is positional disorder of the chloride and trans carbonyl ligands. 相似文献
16.
Jayaraman Pitchaimani Nanjappan Gunasekaran Savarimuthu Philip Anthony Dohyun Moon Vedichi Madhu 《应用有机金属化学》2019,33(6)
A series of air‐stable, phosphine‐free arene ruthenium (II)–NNN pincer complexes (RuL, RuL1, RuL2 and RuL3) have been synthesized and characterized by spectroscopic and single‐crystal X‐ray analysis. Further, arene ruthenium (II)–NNN pincer complexes have been used as catalyst for hydrogenation of nitroaromatics into aniline in the presence of NaBH4 at room temperature. The catalytic process suggested highly chemo‐selective nitroreduction with wide functional group tolerance. 相似文献
17.
Design of pincer complexes based on (methylsulfanyl)acetic/propionic acid amides with ancillary S‐ and N‐donors as potential catalysts and cytotoxic agents
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Svetlana G. Churusova Diana V. Aleksanyan Andrei A. Vasil'ev Ekaterina Yu. Rybalkina Olga Yu. Susova Zinaida S. Klemenkova Rinat R. Aysin Yulia V. Nelyubina Vladimir A. Kozlov 《应用有机金属化学》2018,32(6)
Pincer complexes featuring readily tunable tridentate ligand frameworks comprise one of the most actively studied classes of organometallic and metal–organic compounds and find extensive use in catalysis, organic synthesis, materials science, and other fields of chemistry and allied disciplines. Currently growing attention is devoted to non‐classical ligand scaffolds, such as functionalized carboxamides, which offer multiple options for directed structural modifications. In this study, the reactions of (methylsulfanyl)acetyl and propanoyl chlorides with 2‐(aminomethyl)pyridine, 2‐(2‐aminoethyl)pyridine, 8‐aminoquinoline and 2‐(diphenylthiophosphoryl)aniline afford a series of new pincer‐type ligands based on functionalized carboxamides. The ligands obtained readily undergo direct cyclopalladation under the action of PdCl2(NCPh)2 in dichloromethane at room temperature, resulting in Pd(II) pincer complexes with N,N,S‐ and S,N,S‐donor sets. Importantly, some of the cyclopalladated derivatives can also be produced efficiently under solvent‐free conditions according to the approach recently developed by our group. The complexes obtained have been tested for cytotoxicity against several human cancer cell lines and catalytic activity in the model Suzuki reaction. The results have been compared to those for the related Pd(II) pincer complexes to define the main structure–activity relationships and to outline the most promising structures for further investigations. 相似文献
18.
Organometallic Lewis Acids,Part LXI. Cationic Pentacarbonylrhenium Complexes [(OC)5Re‐L]+BF4– with Aromatic Amines (L) as Ligands
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Aromatic amines (aniline and derivatives) react with (OC)5ReFBF3 to give the cationic complexes [(OC)5Re‐L]+ as BF4– salts under mild conditions and in high yields. Dinuclear, dicationic complexes are formed with o‐ and p‐phenylenediamine. Substitution of tetrafluoroborate by the N‐donors is preferred before attack at a carbonyl ligand. 相似文献
19.
Tomoko Harada Satoko Wada Hidetaka Yuge Takeshi Ken Miyamoto 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):m37-m39
In the two ruthenium(II)–porphyrin–carbene complexes (dibenzoylcarbenyl‐κC)(pyridine‐κN)(5,10,15,20‐tetra‐p‐tolylporphyrinato‐κ4N)ruthenium(II), [Ru(C15H10O2)(C5H5N)(C48H36N4)], (I), and (pyridine‐κN)(5,10,15,20‐tetra‐p‐tolylporphyrinato‐κ4N)[bis(3‐trifluoromethylphenyl)carbenyl‐κC]ruthenium(II), [Ru(C15H8F6)(C5H5N)(C48H36N4)], (II), the pyridine ligand coordinates to the octahedral Ru atom trans with respect to the carbene ligand. The C(carbene)—Ru—N(pyridine) bonds in (I) coincide with a crystallographic twofold axis. The Ru—C bond lengths of 1.877 (8) and 1.868 (3) Å in (I) and (II), respectively, are slightly longer than those of other ruthenium(II)–porphyrin–carbene complexes, owing to the trans influence of the pyridine ligands. 相似文献
20.
Yuan Shi Takuya Suguri Chisato Dohi Hirotsuna Yamada Dr. Satoshi Kojima Prof. Dr. Yohsuke Yamamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(32):10672-10689
A series of Ir–PCP pincer precatalysts [(7–6–7‐RPCP)Ir(H)(Cl)] and [(7–6–7‐ArPCP)Ir(H)(Cl)(MeCN)] bearing a novel “7–6–7” fused‐ring skeleton have been synthesized based upon the postulate that the catalytic species would have durability due to their rather rigid structure and high activity owing to the low but sufficient flexibility of their backbones, which are not completely fixed. Treatment of these precatalysts with NaOtBu gave rise to the active 14 electron (14e) species [(7–6–7‐iPrPCP)Ir] and [(7–6–7‐PhPCP)Ir], which can trap hydrogen and were spectroscopically characterized as the tetrahydride complexes. Both [(7–6–7‐iPrPCP)Ir] and [(7–6–7‐PhPCP)Ir] were found to be highly effective in the transfer dehydrogenation of cyclooctane with tert‐butylethylene as the hydrogen acceptor, the initial reaction rate at high temperature (230 °C) being higher for [(7–6–7‐iPrPCP)Ir] than [(7–6–7‐PhPCP)Ir], and the turnover number (TON) of the overall hydrogen transfer being higher for the latter. Nonetheless, the estimated TONs were as high as 4600 and 4820 for the two complexes at this temperature, respectively, which are unprecedented absolute values. In terms of durability, the [(7–6–7‐PhPCP)Ir] complex is the catalyst of choice for this reaction. Structural analysis and computational studies support the importance of the low flexibility of the ligand core. 相似文献