Anionic polymerization of α-methylene-N-methylpyrrolidone ( MMP ) was carried out in THF at −78∼0 °C with diphenylmethylpotassium (Ph2CHK) and with diphenylmethyllithium (Ph2CHLi) in the presence of Lewis acidic diethylzinc (Et2Zn). Poly( MMP )s possessing predicted molecular weights based on the molar ratios between monomer and initiators and narrow molecular weight distributions (Mw/Mn < 1.1) were obtained in quantitative yields. It was demonstrated that the propagating chain end of poly( MMP ) was stable at −30 °C to form the polymers with well-defined chain structures. From the polymerizations at the various temperatures ranging from −50 to −30 °C, the apparent rate constant and the activation energy of the polymerization were estimated as follows: ln k = −6.93 × 103/T + 25.7 and 57 ± 5 kJ mol−1, respectively. 相似文献
Anionic polymerization of N-methacryloyl-2-methylaziridine ( 1 ) proceeded with 1,1-diphenyl-3-methylpentyllithium (DMPLi) in the presence of LiCl or Et2Zn to give the polymers possessing predicted molecular weights and narrow molecular weight distributions (Mw/Mn < 1.1) at −78 ∼ −40 °C in THF. In each polymerization initiated with DMPLi/LiCl at the various temperatures ranging from −40 to −60 °C, the linear relationship between polymerization time and conversion of monomer was obtained from the GLC analysis. The rate constant and the activation energy of the anionic polymerization for 1 were determined as follows: ln k = −5.85 × 103/T + 23.3 L mol−1 s−1 and 49 ± 4 kJ mol−1, respectively. Poly( 1 ) showed the glass transition temperature at 98 °C, and gave the insoluble product at higher temperature around 150 °C through the thermal cross-linking of highly strained N-acyl-aziridine moiety. 相似文献
Summary: A variety of branched polyethylenes, spanning from semicrystalline LLDPE to completely amorphous, rubbery PE, was obtained from ethylene by homogeneous tandem catalysis using combinations of CoCl2(N) ( 1 ) (N = [1‐(6‐benzo[b]thiophen‐2‐yl‐pyridin‐2‐yl)‐ethylidlene)‐(2,6‐diisopropyl‐phenyl)‐amine) and [(η5‐C5Me4)SiMe2(tBuN)]TiCl2 ( 2 ) in the presence of MAO at 30 °C. The productivity reached a maximum of 4 570 kg PE (mol Ti · h)−1 at χCo = 0.50, yielding a rubbery material with d25 = 0.868 g · cm−3 and Tg = −55 °C.
Conversion of ethylene into branched polyethylene using CoII iminopyridyl complex CoCl2(N) ( 1 ) and TiCl2[(η5‐C5Me4)SiMe2(tBuN)] ( 2 ). 相似文献
Nd4N2Se3 and Tb4N2Se3: Two non‐isotypical Lanthanide(III) Nitride Selenides The non‐isotypical nitride selenides M4N2Se3 of neodymium (Nd4N2Se3) and terbium (Tb4N2Se3) are formed by the reaction of the respective rare‐earth metal with sodium azide (NaN3), selenium and the corresponding rare‐earth tribromide (MBr3) at 900 °C in evacuated silica ampoules after seven days. Each of them crystallizes monoclinically in the space group C2/c with Z = 4 for Nd4N2Se3 (a = 1300.47(4), b = 1009.90(3), c = 643.33(2) pm, β = 90.039(2)°) and in the space group C2/m with Z = 2 for Tb4N2Se3 (a = 1333.56(5), b = 394.30(2), c = 1034.37(4) pm, β = 130.377(2)°), respectively. The crystal structures differ fundamentally in the linkage of the structure dominating N3‐ centred (M3+)4 tetrahedra. In Nd4N2Se3, the [NNd4] units are edge‐linked to bitetrahedra which are cross‐connected to [N(Nd1)(Nd2)]3+ layers via their remaining four corners, whereas the [NTb4] tetrahedra in Tb4N2Se3 share cis‐oriented edges to form strands [N(Tb1)(Tb2)]3+. Both structures contain two crystallographically different M3+ cations, that show coordination numbers of six and seven (Nd4N2Se3) or twice six (Tb4N2Se3), respectively, relative to the anions (N3‐ und Se2‐). Each of the two independent kinds of Se2‐ anions provide the three‐dimensional linkage as well as the charge balance. The particular axial ratio a/c and the monoclinic reflex angle offer two choices for fixing the unit cell of Tb4N2Se3. 相似文献
Acyl- and Alkylidenephosphanes. XXXV. Bis[ N -(trimethylsilyl)iminobenzoyl]phosphanides of Lithium and Zinc – Syntheses as well as NMR Spectroscopic, Structural, and Quantumchemical Studies From the reaction of bis(tetrahydrofuran)lithium bis(trimethylsilyl)phosphanide with two equivalents of benzonitrile in 1,2-dimethoxyethane, the yellow dme complex ( 2 a ) of lithium bis[N-(trimethylsilyl)iminobenzoyl]phosphanide ( 2 ) was obtained in 69% yield. However, the intermediate {1-[N-lithium-N-(trimethylsilyl)amido]benzylidene}trimethylsilylphosphane ( 1 ), formed by an analogous 1 : 1 addition in diethyl ether, turned out to be unstable and as a consequence could be characterized by nmr spectroscopic methods only; attempts to isolate the compound failed, but small amounts of the neutral complex 2 b , with the ligands benzonitrile and tetrahydrofuran coordinated to lithium, precipitated. The reaction of compound 2 with zinc(II) chloride in diethyl ether gives the orange-red spiro-complex zinc bis{bis[N-(trimethylsilyl)iminobenzoyl]phosphanide} ( 3 ); this complex is also formed from bis[N-(trimethylsilyl)iminobenzoyl]phosphane ( 4 ), easily amenable by a lithium hydrogen exchange of 2 a with trifluoroacetic acid [18], and zinc bis[bis(trimethylsilyl)amide]. As derived from nmr spectroscopic studies and x-ray structure determinations, compounds 2 a {δ31P +63.3 ppm; P21/n; Z = 4; R1 = 0.067}, 2 b {δ31P +63.3 ppm; P21/c; Z = 4; R1 = 0.063}, 3 {δ31P +58.2 ppm; C2/c; Z = 4; R1 = 0.037} and 4 {δ31P +58.1 ppm [18]} exist as cyclic 3-imino-2λ3σ2-phosphapropenylamides and -propenylamine, respectively, in solution as well as in the solid state. Unlike hydrogen derivative 4 the bis[N-(trimethylsilyl)iminobenzoyl]phosphanide fragments N,N′-coordinating either a lithium or a zinc cation are characterized by almost completely equalized bond lengths; typical mean distances and angles are: PC 180.3 and 178.7; CN 130.5 and 131.8; N–Si 175.3 and 179.3; N–Li 202.3; N–Zn 203.5 pm; CPC 108.8° and 110.5°; PCN 130.9° and 132.9°; CN–Li 113.0°, CN–Zn 117.4°; N–Li–N 104.6°; N–Zn–N 108.8°. Alterations in the shape of the six membered chelate rings, caused by an exchange of the 3-imino-2λ3σ2-phosphapropenylamide or related 2λ3σ2-phospha-1,3-dionate units for the corresponding phosphorus free ligands, are discussed in detail. The results of quantumchemical DFT-B3LYP calculations coincide very well with the experimentally obtained findings. 相似文献
The Schiff base‐containing pendant monoaza crown ether HL1, HL2, HL3 and HL4 have been synthesized by condensation of salicylaldehyde with N‐(4‐aminoaryl) monoaza crown ethers, which were prepared conveniently from 4‐nitro‐N, N‐di(hydroxyethyl) aniline or 4‐nitrobenzyl chloride via cyclization or condensation and reduction. The structures of HL1—HL4 were verified by 1H NMR, IR spectra, MS and elemental analysis. Moreover, the oxygenation constants (KO2) and thermodynamic parameters (δH0 and δS0) of their cobalt(II) complexes were determined in the range of ?5 °C to 25 °C, and the effect of crown ring bonded to a Schiff base on the dioxygen affinities of cobalt(II) complexes was also observed as compared to the uncrowned analogue (CoL). 相似文献
(C2H10N2)[BPO4F2] — Strukturbeziehungen zwischen [BPO4F2]2— und [Si2O6]4— Colourless crystals of (C2H10N2)[BPO4F2] were prepared from mixture of ethylendiamine, H3BO3, BF3 · C2H5NH2, H3PO4 and HCl under mild hydrothermal conditions (220 °C). The crystal structure was determined by single crystal methods (triclinic, P1¯ (no. 2), a = 451.85(5) pm, b = 710.20(8) pm, c = 1210.2(2) pm, α = 86.08(1)°, β = 88.52(2)°, γ = 71.74(1)°, Z = 2) and contains infinite tetrahedral zweier‐single‐chains {[BPO4F2]2—} which are isoelectronic (48e—) with the polyanions {[Si2O6]4—} of the pyroxene family. 相似文献