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1.
Synthesis and Characterization of a Family of POCOP Pincer Complexes with Nickel: Reactivity Towards CO2 and Phenylacetylene
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Klara J. Jonasson Dr. Ola F. Wendt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11894-11902
A cyclohexyl‐based POCOP pincer ligand (POCOP=cis‐1,3‐bis(di‐tert‐butylphosphinito)cyclohexyl) cyclometalates with nickel to generate a series of new POCOP‐supported NiII complexes, including the halide, hydride, methyl, and phenyl species. trans‐[NiCl{cis‐1,3‐bis(di‐tert‐butylphosphinito)cyclohexane}], [(POCOP)NiCl] ( 1 a ) and the analogous bromide complex ( 1 b ) were synthesized and fully characterized by NMR spectroscopy and X‐ray crystallography. Cyclic voltammetry measurements of 1 a and 1 b alongside their bis(phosphine) analogues [(PCP)NiCl] ( 2 a ) and [(PCP)NiCl] ( 2 a ) (PCP=cis‐1,3‐bis(di‐tert‐butylphosphino)cyclohexyl) indicate a reduced electron density at the metal center upon introducing electron‐withdrawing oxygen atoms in the pincer arms. The methyl [(POCOP)NiMe] ( 3 ) and phenyl [(POCOP)NiPh] ( 4 ) complexes were formed from 1 a by reaction with the corresponding organolithium reagents. 1 a also reacts with LiAlH4 to give the hydride complex [(POCOP)NiH] ( 5 ). The methyl complex 3 reacts with phenyl acetylene to give the acetylide complex [(POCOP)NiCCPh] ( 6 ). The reactivity of compounds 3 – 5 towards CO2 was studied. The hydride complex 5 and the methyl complex 3 both underwent CO2 insertion to form the formate species [(POCOP)NiOCOH] ( 7 ) and acetate species [(POCOP)NiOCOCH3] ( 8 ), respectively, although with a higher barrier of insertion in the latter case. Compound 4 was unreactive towards CO2 even at elevated temperatures. Complexes 3 – 8 were all characterized by NMR spectroscopy and X‐ray crystallography. 相似文献
2.
Wolfram Feuerstein Dr. Christof Holzer Xin Gui Dr. Lilly Neumeier Prof. Dr. Wim Klopper Prof. Dr. Frank Breher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(71):17156-17164
We herein report on new synthetic strategies for the preparation of pyridine and imidazole substituted 2,2’-dihalo biphenyls. These structures are pre-ligands suitable for the preparation of respective stannoles. The latter can successfully be transmetalated to K[AuCl4] forming non-palindromic [(C^C^D)AuIII] pincer complexes featuring a lateral pyridine (D=N) or N-heterocyclic carbene (NHC, D=C’) donor. The latter is the first report on a pincer complex with two formally anionic sp2 and one carbenic carbon donor. The [(C^C^D)AuIII] complexes show intense phosphorescence in solution at room temperature. We discuss the developed multistep strategy and touch upon synthetic challenges. The prepared complexes have been fully characterized including X-ray diffraction analysis. The gold(III) complexes’ photophysical properties have been investigated by absorption and emission spectroscopy as well as quantum chemical calculations on the quasi-relativistic two-component TD-DFT and GW/Bethe–Salpeter level including spin–orbit coupling. Thus, we shed light on the electronic influence of the non-palindromic pincer ligand and reveal non-radiative relaxation pathways of the different ligands employed. 相似文献
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Dr. Jingjun Hao Berline Mougang‐Soumé Boris Vabre Prof. Dr. Davit Zargarian 《Angewandte Chemie (International ed. in English)》2014,53(12):3218-3222
We describe the results of a study on the stabilities of pincer‐type nickel complexes relevant to catalytic hydroalkoxylation and hydroamination of olefins, C? C and C? X couplings, and fluorination of alkyl halides. Complexes [(POCsp3OP)NiX] are stable for X=OSiMe3, OMes (Mes=1,3,5‐Me3C6H2), NPh2, and CC? H, whereas the O(tBu) and N(SiMe3)2 derivatives decompose readily. The phenylacetylide derivative transforms gradually into the zero‐valent species cis‐[{κP,κC,κC′‐(iPr2POCH2CHCH2)}Ni{η2,κC,κC′‐(iPr2P(O)CCPh)}]. Likewise, attempts to prepare [(POCsp3OP)NiF] gave instead the zwitterionic trinuclear species [{(η3‐allyl)Ni}2‐{μ,κP,κO‐(iPr2PO)4Ni}]. Characterization of these two complexes provides concrete examples of decomposition processes that can dismantle POCsp3OP‐type pincer ligands by facile C? O bond rupture. These results serve as a cautionary tale for the inherent structural fragility of pincer systems bearing phosphinite donor moieties, and provide guidelines on how to design more robust analogues. 相似文献
4.
Dr. Jingshun Zhang Zhiqiang Hao Dr. Wei Gao Lan Xin Lei Zhang Prof. Ying Mu 《化学:亚洲杂志》2013,8(9):2079-2087
A series of NCO/NCS pincer precursors, 3‐(Ar2OCH2)‐2‐Br‐(Ar1N?CH)C6H3 ((Ar1NCOAr2)Br, 3a , 3b , 3c , 3d ) and 3‐(2,6‐Me2C6H3SCH2)‐2‐Br‐(Ar1N?CH)C6H3 ((Ar1NCSMe)Br, 4a and 4b ) were synthesized and characterized. The reactions of [Ar1NCOAr2]Br/ [Ar1NCSMe]Br with nBuLi and the subsequent addition of the rare‐earth‐metal chlorides afforded their corresponding rare‐earth‐metal–pincer complexes, that is, [(Ar1NCOAr2)YCl2(thf)2] ( 5a , 5b , 5c , 5d ), [(Ar1NCOAr2)LuCl2(thf)2] ( 6a , 6d ), [(Ar1NCOAr2)GdCl2(thf)2] ( 7 ), [{(Ar1NCSMe)Y(μ‐Cl)}2{(μ‐Cl)Li(thf)2(μ‐Cl)}2] ( 8 , 9 ), and [{(Ar1NCSMe)Gd(μ‐Cl)}2{(μ‐Cl)Li(thf)2(μ‐Cl)}2] ( 10 , 11 ). These diamagnetic complexes were characterized by 1H and 13C NMR spectroscopy and the molecular structures of compounds 5a , 6a , 7 , and 10 were well‐established by X‐ray diffraction analysis. In compounds 5a , 6a , and 7 , all of the metal centers adopted distorted pentagonal bipyramidal geometries with the NCO donors and two oxygen atoms from the coordinated THF molecules in equatorial positions and the two chlorine atoms in apical positions. Complex 10 is a dimer in which the two equal moieties are linked by two chlorine atoms and two Cl? Li? Cl bridges. In each part, the gadolinium atom adopts a distorted pentagonal bipyramidal geometry. Activated with alkylaluminum and borate, the gadolinium and yttrium complexes showed various activities towards the polymerization of isoprene, thereby affording highly cis‐1,4‐selective polyisoprene, whilst the NCO? lutetium complexes were inert under the same conditions. 相似文献
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The nature of halogen bonding in five complexes formed between the thiocyanate (NCS) radical and a BrCl molecule was analyzed by quantum theory of atoms in molecules (QTAIM) and electron‐localization function (ELF) in this paper. The calculated results show that the geometry of the halogen atom bonded at the N‐atom is stable than those bonded at S‐ or C‐atom. The molecular electrostatic potentials determine the geometries and stabilities of the complexes. The valence basin of the S‐ or N‐atom in the electron‐donating NCS radical is compressed and its population decreases during the process of formation of the halogen‐bonded complexes. 相似文献
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Dr. Klara J. Jonasson Dr. Alexey V. Polukeev Dr. Rocío Marcos Prof. Mårten S. G. Ahlquist Prof. Ola F. Wendt 《Angewandte Chemie (International ed. in English)》2015,54(32):9372-9375
Despite significant progress in recent years, the cleavage of unstrained C(sp3)? C(sp3) bonds remains challenging. A C? C coupling and cleavage reaction in a PC(sp3)P iridium pincer complex is mechanistically studied; the reaction proceeds via the formation of a carbene intermediate and can be described as a competition between α‐hydrogen and α‐alkyl elimination; the latter process was observed experimentally and is an unusual way of C(sp3)? C(sp3) bond scission, which has previously not been studied in detail. Mechanistic details that are based upon kinetic studies, activation parameters, and DFT calculations are also discussed. A full characterization of a C? C agostic intermediate is presented. 相似文献
9.
The C−F bond activation of pentafluoropyridine and 2,3,5,6-tetrafluoropyridine at [Ni(cod)2] (cod=1,5-cyclooctadiene) in the presence of the phosphine PPh2(Ind) (Ind=3-methyl-2-indolyl) led to the formation of the nickel(II) fluorido bis(phosphine) complexes trans-[Ni(F)(2-C5NF4){PPh2(Ind)}2] and trans-[Ni(F)(2-C5HNF3){PPh2(Ind)}2]. The complexes are characterized by the presence of intramolecular hydrogen bonds between the NH group of the phosphine ligands and the fluorido ligand. Stochiometric model reactions of nickel(II) fluorido complexes with PhB(OH)2 revealed that the former can be considered as intermediates in Suzuki–Miyaura cross coupling reactions. Catalytic experiments were attempted using 10 mol-% of trans-[Ni(F)(2-C5NF4){PPh2(Ind)}2] as catalyst and the activities of the PPh2(Ind) complex were compared to the ones of an analogous nickel(II) fluorido complex, bearing PPh3 instead of PPh2(Ind) as ligands. The latter exhibited a somewhat lower catalytic activity suggesting a slight influence of the H-bonds in the outer coordination sphere. 相似文献
10.
《Journal of Dispersion Science and Technology》2013,34(5):683-689
Abstract The effects of two metal complexes of 2,2′‐dipyridylamine (bpya) ligand, [(bpya)Cu]Cl2 and [(bpya)Zn]Cl2, in promoting the hydrolysis of bis(4‐nitrophenyl) phosphate (BNPP) have been kinetically investigated in Brij35 micellar solution and at 298 K, pH ranging from 6.41 to 8.6. In neutral micellar solution at 298 K, pH 7.02, the rate constants for the catalytic hydrolysis of BNPP by [(bpya)Cu]Cl2 and [(bpya)Zn]Cl2 are 1.2 × 106 times and 1.5 × 105 times higher than those for the spontaneous hydrolysis, respectively. Kinetic studies show that the active species in the catalytic hydrolysis of BNPP is the aquo‐hydroxy form, and the relative kinetic and thermodynamic parameters indicate that the mechanism of the reaction involves intramolecular nucleophilic attack on the metal center‐bound diester. 相似文献
11.
Kuheli Das Amitabha Datta Chittaranjan Sinha Jui-Hsien Huang Eugenio Garribba Ching-Sheng Hsiao Chin-Lin Hsu 《ChemistryOpen》2012,1(2):80-89
The reactions of the tridentate hydrazone ligand, N′-[1-(pyridin-2-yl)ethylidene]acetohydrazide (HL), obtained by condensation of 2-acetylpyridine with acetic hyadrazide, with copper nitrate trihydrate in the presence of thiocyanate, or with CuCl2 produce two distinct coordination compounds, namely a one-dimensional helical coordination chain of [CuL(NCS)]n (1) units, and a doubly chlorido-bridged dinuclear complex [Cu2L2Cl2] (2) (where L=CH3C(O)=N–N=CCH3C5H4N). Single-crystal X-ray structural determination studies reveal that in complex 1, a deprotonated hydrazone ligand L− coordinates a copper(II) ion that is bridged to two neighbouring metal centres by SCN− anions, generating a one-dimensional helical coordination chain. In complex 2, two symmetry-related, adjacent copper(II) coordination entities are doubly chlorido-bridged, producing a dicopper entity with a Cu⋅⋅⋅Cu distance of 3.402 (1) Å. The two coordination compounds have been fully characterised by elemental analysis, spectroscopic techniques including IR, UV–vis and electron paramagnetic resonance, and variable-temperature magnetic studies. The biological effects of 1 and 2 on the viability of human colorectal carcinoma cells (COLO-205 and HT-29) were evaluated using an MTT assay, and the results indicate that these complexes induce a decrease in cell-population growth of human colorectal carcinoma cells with apoptosis. 相似文献
12.
P. Akilan 《Supramolecular chemistry》2013,25(7):495-504
A new series of macrobicyclic ditopic receptors is derived from the precursor compound 3,4:10,11-dibenzo-1,13[N,N′-bis{(3-formyl-2-hydroxy-5-methyl)benzyl}di-aza]-5,9-dioxocyclohexadecane. Using this precursor, mono- and binuclear nickel(II) complexes of type [NiL](ClO4) and [Ni2L](ClO4)2 have been synthesized to undertake electrochemical and catalytic studies on the basis of macrocyclic ring size. The receptor is a tricompartmental macrocycle consisting of ether oxygen, tertiary nitrogen and imine nitrogen atoms. The redox studies of these systems show that the nickel(II) complexes undergo quasi-reversible one-electron reduction and oxidation. All the nickel(II) complexes have square planar geometry and are EPR silent. Examination of the kinetics of the hydrolysis of 4-nitrophenyl phosphate shows that the catalytic activities of the complexes increase with the macrocyclic ring size of the complexes. As the macrocyclic ring size of the complexes increases, the spectral, electrochemical and catalytic studies of the complexes show considerable variation due to distortion in the geometry around the nickel(II) centre. 相似文献
13.
The incongruent solvation of M(I)4P6 species (M(I) = K, Rb, Cs) in liquid ammonia leads to a broad variety of polyphosphides such as P7(3-), P11(3-), and the putatively aromatic P4(2-) and P5(-), which we investigated by using NMR spectroscopy and single-crystal X-ray structure analysis. The structures of Cs2P4 x 2 NH3, (K@[18]crown-6)3K3(P7)2 x 10 NH3, Rb3P7 x 7 NH3, and (Rb@[18]crown-6)3P7 x 6 NH3 are discussed and compared. The electron localization function ELF is used in a comparison of the chemical bonding of various phosphorus species. The variances of the basin populations provide a well-established measure for electron delocalization and therefore aromaticity. While comparable variance is calculated for P4(2-) and P5(-) it is observed in the lone pairs rather than in the basin populations of the bonds as in the prototypical aromatic hydrocarbons such as benzene or the cyclopentadienide anion. For this behavior, the term "lone pair aromaticity" is proposed. 相似文献
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A series of substituted dienophiles 1—10 and three 1,2-diazadienes namely D-1, D-2, D-3 were chosen to understand the reactivity and selectivity of Diels-Alder cycloaddition. The global and local electrophilicity patterns have been evaluated on a series of cycloaddition reactions to assess the reaction pathways (NDAC/IEDDAC) using the absolute scale of electrophilicity proposed by Parr et al. Regional electrophilicity at the active sites of the reagents involved in Diels-Alder processes has been described on a quantitative basis using local or regional electrophilicity index i.e. Fukui function. Good qualitative/quantitative comparison was found between molecular energy gaps and global electronic parameters, which has been employed to assess the cycloaddition pathways successfully. 相似文献
16.
[Pb(HL)(phen)]n(1) and [Cd3L2(phen)]n(2), where phen = 1,10-phenanthroline and L = 4,4'-(2-carboxylatopropane-1,3-diyl)dibenzoate, were hydrothermally prepared and fully characterized by X-ray single-crystal diffraction, infrared spectroscopy and thermogravimetric analyses. The decomposition temperature of 1 and 2 was measured to be ca. 304 and 416 ℃, respectively. The charge transfer transition based absorption of 1 and 2 was also verified by the powder scattering spectra and theoretical analyses. 相似文献
17.
C. P. Bhasin J. P. Patel M. L. Desai 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2509-2524
Dialkyldithiophosphate derivatives of macrocyclic complexes of Pb(II), having N2S2 potential donors, of the general formula, [Pb(L)S2P(OR)2] (where L = macrocyclic ligands L1, L2, L3, L4 & L5 and R = CH3-, C3H7 n- & C3H7 i-) have been Synthesized from the reactions of [Pb(L)X2] (where X = Cl, NO3, or CH3COO) with sodium dialkyl dithiophosphates in 1:2 molar ratios in THF. Fifteen new derivatives have been synthesized by the combination of five macrocyclic complexes of 14–20 member rings with three different types of dialkyldithiophosphate. These compounds have been characterized by elemental analysis, molar conductance, molecular weight determination, IR, 1H NMR, 13C, and 31P NMR. Molecular weight determinations of these complexes indicate their monomeric nature. An octahedral structure is proposed. 相似文献
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Félix Zamora Víctor M. González José M. Pérez José R. Masaguer Carlos Alonso Carmen Navarro-Ranninger 《应用有机金属化学》1997,11(8):659-666
In this paper we describe the synthesis and chemical characterization of three new Pd(II)–imidazoline complexes: [PdCl2 (C6H5–CH2–C3H5N2)2] (2), [PdCl(SEt2) (C6H4-C3H5N2)] (5) and [Pd(C6H4-C3H5N2) (μ-Br)]2 (6). We have also analyzed the DNA modifications and in vitro antileukaemic activity of these compounds and of their previously reported analogs [Pd Cl2 (C6H5–C3H5N2)2] (1), [Pd (C6H4–C3H5N2) (μ-OAc)]2 (3), [Pd (C6H4–C3H5N2) (μ-Cl)]2 (4) and [Pt(C6H4–C3H5N2)(μ-Cl] (7). All these compounds modify the DNA secondary structure since they alter the melting temperature (Tm) of the DNA. Circular dichroism spectra indicated, moreover, that compounds 3, 5 and 6 induced higher modification on the double helix than compounds 1, 2 and 4. While compounds 1, 2 and 5 seem to induce slight changes in the electrophoretic mobility of the open and covalently closed circular forms of pUC8 DNA at high ri (input molar ratio of Pd or Pt to nucleotides), compounds 3, 6 and 7 do not modify at any ri the tertiary structure of the plasmid DNA. Antileukaemic tests suggest that compounds 1, 4 and 7 exhibit important cytotoxic activity since their IC50 values against HL-60 human leukaemic cells were below 10 μg ml−1. © 1997 John Wiley & Sons, Ltd. 相似文献
20.
《应用有机金属化学》2017,31(9)
Monomeric bis(isopropoxy) titanium complexes LTi(Oi Pr)2 (L = ─ OC6H2–4‐R1–6‐R2–2‐CH2N[(CH2)2N(R3)2]CH2–4‐R4–6‐R5‐C6H2O ─ , R1 = R2 = t Bu, R3 = Et, R4 = R5 = Cl, (L1)Ti(Oi Pr)2; R1 = R2 = Me, R3 = Et, R4 = R5 = Me, (L2)Ti(Oi Pr)2; R1 = R2 = t Bu, R3 = Et, R4 = OMe, R5 = t Bu, (L3)Ti(Oi Pr)2; R1 = R4 = OMe, R3 = Et, R2 = R5 = t Bu, (L4)Ti(Oi Pr)2; R1 = R2 = t Bu, R3 = Me, R4 = OMe, R5 = t Bu, (L5)Ti(Oi Pr)2) supported by amine bis(phenolate) ligands were synthesized and characterized using NMR spectroscopy and elemental analysis. The solid‐state structure of (L3)Ti(Oi Pr)2 was determined using single‐crystal X‐ray diffraction. (L1–5)Ti(Oi Pr)2 were all found to initiate the ring‐opening polymerization of l ‐lactide and rac ‐lactide in a controlled manner at 110–160°C. As shown by kinetic studies, (L1)Ti(Oi Pr)2 polymerized l ‐lactide faster than did (L2–5)Ti(Oi Pr)2. In addition, good number‐average molecular weight and narrow polydispersity index (1.00–1.71) of polymers were also obtained. The microstructure of the polymers and a possible mechanism of coordination–insertion of polymerization were evidenced by MALDI‐TOF and 1H NMR spectra of the polylactides. 相似文献