共查询到20条相似文献,搜索用时 890 毫秒
1.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(45):14245-14248
The generation of iron(V) nitride complexes, which are targets of biomimetic chemistry, is reported. Temperature‐dependent ion spectroscopy shows that this reaction is governed by the spin‐state population of their iron(III) azide precursors and can be tuned by temperature. The complex [(MePy2TACN)Fe(N3)]2+ (MePy2TACN=N ‐methyl‐N ,N ‐bis(2‐picolyl)‐1,4,7‐triazacyclononane) exists as a mixture of sextet and doublet spin states at 300 K, whereas only the doublet state is populated at 3 K. Photofragmentation of the sextet state complex leads to the reduction of the iron center. The doublet state complex photodissociates to the desired iron(V) nitride complex. To generalize these findings, we show results for complexes with cyclam‐based ligands. 相似文献
2.
Zhigang Xue Seok Kyun Noh Won Seok Lyoo 《Journal of polymer science. Part A, Polymer chemistry》2008,46(9):2922-2935
2‐[(Diphenylphosphino)methyl]pyridine (DPPMP) was successfully used as a bidentate ligand in the iron‐mediated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) with various initiators and solvents. The effect of the catalytic system on ATRP was studied systematically. Most of the polymerizations with DPPMP ligand were well controlled with a linear increase in the number‐average molecular weights (Mn) versus conversion and relatively low molecular weight distributions (Mw/Mn = 1.10–1.3) being observed throughout the reactions, and the measured molecular weights matched the predicted values. Initially added iron(III) bromide improved the controllability of the polymerization reactions in terms of molecular weight control. The ratio of ligand to metal influenced the controllability of ATRP system, and the optimum ratio was found to be 2:1. It was shown that ATRP of MMA with FeX2/DPPMP catalytic system (X = Cl, Br) initiated by 2‐bromopropionitrile (BPN) was controlled more effectively in toluene than in polar solvents. The rate of polymerization increased with increasing the polymerization temperature and the apparent activation energy was calculated to be 56.7 KJ mol?1. In addition, reverse ATRP of MMA was able to be successfully carried out using AIBN in toluene at 80 °C. Polymerization of styrene (St) was found to be controlled well by using the PEBr/FeBr2/DPPMP system in DMF at 110 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2922–2935, 2008 相似文献
3.
Dan He Zhigang Xue Mohd Yusuf Khan Seok Kyun Noh Won Seok Lyoo 《Journal of polymer science. Part A, Polymer chemistry》2010,48(1):144-151
Styrene polymerization via generation of activators by monomer addition (GAMA) for atom transfer radical polymerization (ATRP) has been examined extensively with bulk FeX3 and FeX2 at 110 °C in conjunction with various phosphorus‐bearing ligands. It was found that GAMA possesses advantages over normal ATRP. Most importantly, narrower polydispersity index (PDI) values were observed from the styrene polymerizations with Fe(III) over those with Fe(II). Every instance of 2‐(diphenylphosphino)‐N,N′‐dimethyl‐[1,1′‐biphenyl]‐2‐amine and 2‐(diphenylphosphino) pyridine with the Fe(III) system were controlled excellently without addition of any radical initiator or reducing agent additives. Initiator type was found to exert a significant factor to influence on the controllability of polymerization. The initiation of 1‐phenylethyl chloride and methyl‐2‐chloropropionate gave rise to formation of polymers with narrow PDI (1.05–1.20), whereas those from 1‐phenylethyl bromide increased to 1.35. The GAMA of bulk styrene exhibited the best performance in terms of both rate and controllability compared with toluene and anisole. Both formation of block copolymer from the macroinitiator and efficient perturbation of polymerization with 2,2,6,6‐tetramethylpiperidine 1‐oxyl provided firm evidence to support the living and radical characteristics for the GAMA of styrene. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 144–151, 2010 相似文献
4.
Huiqi Zhang Ulrich S. Schubert 《Journal of polymer science. Part A, Polymer chemistry》2004,42(19):4882-4894
The controlled atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) catalyzed by iron halide/N‐(n‐hexyl)‐2‐pyridylmethanimine (NHPMI) is described. The ethyl 2‐bromoisobutyrate (EBIB)‐initiated ATRP with [MMA]0/[EBIB]0/[iron halide]0/[NHPMI]0 = 150/1/1/2 was better controlled in 2‐butanone than in p‐xylene at 90 °C. Initially added iron(III) halide improved the controllability of the reactions in terms of molecular weight control. The p‐toluenesulfonyl chloride (TsC1)‐initiated ATRP were uncontrolled with [MMA]0/[TsC1]0/[iron halide]0/[NHPMI]0 = 150/1/1/2 in 2‐butanone at 90 °C. In contrast to the EBIB‐initiated system, the initially added iron(III) halide greatly decreased the controllability of the TsC1‐initiated ATRP. The ration of iron halide to NHPMI significantly influenced the controllability of both EBIB and TsC1‐initiated ATRP systems. The ATRP with [MMA]0/[initiator]0/[iron halide]0/[NHPMI]0 = 150/1//1/2 provided polymers with PDIs ≥ 1.57, whereas those with [iron halide]0/[NHPMI]0 = 1 resulted in polymers with PDIs as low as 1.35. Moreover, polymers with PDIs of approximately 1.25 were obtained after their precipitation from acidified methanol. The high functionality of the halide end group in the obtained polymer was confirmed by both 1H NMR and a chain‐extenstion reaction. Cyclic voltammetry was utilized to explain the differing catalytic behaviors of the in situ‐formed complexes by iron halide and NHPMI with different molar ratios. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4882–4894, 2004 相似文献
5.
High‐Spin Iron(I) and Iron(0) Dinitrogen Complexes Supported by N‐Heterocyclic Carbene Ligands 下载免费PDF全文
Dr. Zhenwu Ouyang Jun Cheng Dr. Lingling Li Xiaoli Bao Prof. Dr. Liang Deng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14162-14165
The use of 1,3‐dicyclohexylimidazol‐2‐ylidene (ICy) as ligand has enabled the preparation of the high‐spin tetrahedral iron(I)‐ and iron(0)–N2 complexes, namely [(ICy)3Fe(N2)][BPh4] ( 1 ) and [(ICy)3Fe(N2)] ( 2 ), the electronic structures of which have been established by various spectroscopic characterization and DFT calculations. The frequency of the N–N stretching resonance of the iron(0)–N2 complex is the lowest among the reported terminal N2 complexes of iron, signifying the beneficial roles of strongly σ‐donating ligands in combination with the high‐spin low‐valent iron center in promoting N2‐activation. The iron(0)–N2 complex can convert reversibly to the low‐spin iron(II)‐N2 hydride complex [(ICy)2(ICy′)Fe(N2)(H)] ( 4 ). 相似文献
6.
Summary: A highly active and versatile CuBr2/N,N,N′,N′‐tetra[(2‐pyridal)methyl]ethylenediamine (CuBr2/TPEN)‐tertiary amine catalyst system has been developed for atom transfer radical polymerization via activator‐generated‐by‐electron‐transfer (AGET ATRP). The catalyst mediates good control of the AGET ATRPs of methyl acrylate, methyl methacrylate, and styrene at 1 mol‐% catalyst relative to initiator. A mechanism study shows that tertiary amines such as triethylamine reduces the CuBr2/TPEN complex to CuBr/TPEN.
7.
U. Tunca T. Erdogan G. Hizal 《Journal of polymer science. Part A, Polymer chemistry》2002,40(12):2025-2032
An asymmetric difunctional initiator 2‐phenyl‐2‐[(2,2,6,6 tetramethylpiperidino)oxy] ethyl 2‐bromo propanoate ( 1 ) was used for the synthesis of ABC‐type methyl methacrylate (MMA)‐tert‐butylacrylate (tBA)‐styrene (St) triblock copolymers via a combination of atom transfer radical polymerization (ATRP) and stable free‐radical polymerization (SFRP). The ATRP‐ATRP‐SFRP or SFRP‐ATRP‐ATRP route led to ABC‐type triblock copolymers with controlled molecular weight and moderate polydispersity (Mw/Mn < 1.35). The block copolymers were characterized by gel permeation chromatography and 1H NMR. The retaining chain‐end functionality and the applying halide exchange afforded high blocking efficiency as well as maintained control over entire routes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2025–2032, 2002 相似文献
8.
Dr. Robert Langer Dr. Mark A. Iron Dr. Leonid Konstantinovski Dr. Yael Diskin‐Posner Dr. Gregory Leitus Yehoshoa Ben‐David Prof. Dr. David Milstein 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(23):7196-7209
The new, structurally characterized hydrido carbonyl tetrahydridoborate iron pincer complex [(iPr‐PNP)Fe(H)(CO)(η1‐BH4)] ( 1 ) catalyzes the base‐free hydrogenation of ketones to their corresponding alcohols employing only 4.1 atm hydrogen pressure. Turnover numbers up to 1980 at complete conversion of ketone were reached with this system. Treatment of 1 with aniline (as a BH3 scavenger) resulted in a mixture of trans‐[(iPr‐PNP)Fe(H)2(CO)] ( 4 a ) and cis‐[(iPr‐PNP)Fe(H)2(CO)] ( 4 b ). The dihydrido complexes 4 a and 4 b do not react with acetophenone or benzaldehyde, indicating that these complexes are not intermediates in the catalytic reduction of ketones. NMR studies indicate that the tetrahydridoborate ligand in 1 dissociates prior to ketone reduction. DFT calculations show that the mechanism of the iron‐catalyzed hydrogenation of ketones involves alcohol‐assisted aromatization of the dearomatized complex [(iPr‐PNP*)Fe(H)(CO)] ( 7 ) to initially give the Fe0 complex [(iPr‐PNP)Fe(CO)] ( 21 ) and subsequently [(iPr‐PNP)Fe(CO)(EtOH)] ( 38 ). Concerted coordination of acetophenone and dual hydrogen‐atom transfer from the PNP arm and the coordinated ethanol to, respectively, the carbonyl carbon and oxygen atoms, leads to the dearomatized complex [(iPr‐PNP*)Fe(CO)(EtO)(MeCH(OH)Ph)] ( 32 ). The catalyst is regenerated by release of 1‐phenylethanol, followed by dihydrogen coordination and proton transfer to the coordinated ethoxide ligand. 相似文献
9.
A new copper catalyst containing chlorine and a photo‐labile diethylthiocarbamoylthiyl group was successfully employed in the reverse ATRP of methyl methacrylate (MMA). The polymeric chains were end‐capped with S2CNEt2, due to pseudo‐halogen atom‐transfer reaction between active and dormant species. Photopolymerization of this PMMA in the presence of fresh MMA and styrene monomers at ambient temperature yielded chain‐extended PMMA and MMA/styrene block copolymers, respectively.
10.
Dan He Seok Kyun Noh Won Seok Lyoo 《Journal of polymer science. Part A, Polymer chemistry》2011,49(21):4594-4602
Past research has examined the atom transfer radical polymerization (ATRP) with high oxidation state metal complexes and without the need for any additives such as reducing agent or free radical initiator. To extend this research, half‐metallocene ruthenium(III) (Ru(III)) catalysts were used for the polymerization of methyl methacrylate (MMA) for the first time. These catalysts were generated in situ simply by mixing phosphorus‐containing ligand and pentamethylcyclopentadienyl (Cp*) Ru(III) polymer ((Cp*RuCl2)n). The complexes in their higher oxidation state such as Cp*RuCl2(PPh3) were air‐stable, highly active, and removable catalysts for the ATRPs of MMA with both precision control of molecular weight and narrow polydispersity index. The addition of ppm amount of metal catalyst contributed to the formation of very well‐defined homopolymers and copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
11.
Mohd Yusuf Khan Xiangxiong Chen Seung Woo Lee Seok Kyun Noh 《Macromolecular rapid communications》2013,34(15):1225-1230
Atom transfer radical polymerization (ATRP) catalyzed by high oxidation state metal salts of FeX3 is developed for the first time in the absence of both external initiator and reducing agent. Methyl methacrylate (MMA) and styrene are polymerized successfully using FeX3/Phosphorous ligands with well‐controlled molecular weight distributions (=1.5). The molecular weight of the polymers increases with monomer consumption with the progress of time and the polymerization behaviors show a decent ATRP trend. Activators and initiators are suggested to generate in situ by the addition reaction of MMA and one equivalent of FeX3. The PMMA synthesized from without‐initiator system is characterized by 1H, 13C and DEPT (distortionless enhancement by polarization transfer nuclear magnetic resonance) nuclear magnetic resonance spectroscopy. Chain extension and copolymerization experiments prove the livingness of the obtained polymer.
12.
David Fournier Sagrario Pascual Vronique Montembault Laurent Fontaine 《Journal of polymer science. Part A, Polymer chemistry》2006,44(18):5316-5328
New supported catalytic systems based on the immobilization of a ligand onto supported (co)polymers were prepared, allowing copper immobilization onto a solid support during the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). These supported catalysts were elaborated by the ATRP of 2‐vinyl‐4,4‐dimethyl‐5‐oxazolone and/or styrene onto a Wang resin initiator. Two different approaches were used, involving well‐defined architectures synthesized by ATRP. First, a supported electrophilic homopolymer [Wang‐g‐poly(2‐vinyl‐4,4‐dimethyl‐5‐oxazolone)] was synthesized to obtain an azlactone ring at each repetitive unit, and a supported statistical copolymer [Wang‐g‐poly(2‐vinyl‐4,4‐dimethyl‐5‐oxazolone‐stat‐styrene)] was synthesized to introduce a distance between the azlactone rings. The azlactone‐based (co)polymers were then modified by a reaction with N,N,N′,N′‐tetraethyldiethylenetriamine (TEDETA) to create supported complexing sites for copper bromide. The ATRP of MMA was studied with these supported ligands, and a first‐order kinetic plot was obtained, but high polydispersity indices of the obtained poly(methyl methacrylate) were observed (polydispersity index > 2). On the other hand, the supported ATRP of styrene was performed, followed by the nucleophilic substitution of bromine by TEDETA (Wang‐g‐polystyrene–N,N,N′,N′‐tetraethyldiethylenetriamine) at the chain end of the grafted polystyrene chains. This strategy led the ligand away from the core bead, depending on the length of the polystyrene block (number‐average molecular weight determined by size exclusion chromatography = 1100–2250 g/mol). These supported complexes mediated a controlled polymerization of MMA, yielding polymers with controlled molar masses and low polydispersity indices. Moreover, after the polymerization, 96% of the initial copper was kept in the beads. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5316–5328, 2006 相似文献
13.
Using the ligands N‐methylimidazole ( MeIm ), N‐ethylimidazole ( EtIm ), N‐propylimidazole ( PrIm ), and 1‐methyl‐1H‐1, 2, 4‐triazole ( MeTz ) three series with a total of 13 iron(II) complexes were isolated. The series comprise of the following complexes: (a) [Fe( MeIm )6](ClO4)2 ( 1 ), [Fe( EtIm )6](ClO4)2 ( 2 ), [Fe( PrIm )6](ClO4)2( 3 ), [Fe( MeTz )6](ClO4)2 ( 4 ), [Fe( MeIm )6](MeSO3)2 ( 5 ), [Fe( EtIm )6](MeSO3)2 ( 6 ), and [Fe( MeTz )6](BF4)2 ( 10 ); (b) [Fe( MeIm )4(MeSO3)2]( 7 ), [Fe( EtIm )4(MeSO3)2] ( 8 ), and [Fe( PrIm )4(MeSO3)2] ( 9 ); (c) [Fe( MeIm )4(NCS)2] ( 15 ), [Fe( EtIm )4(NCS)2] ( 16 ), and [Fe( MeTz )4(NCS)2] ( 17 ). Single crystal X‐ray diffraction studies were performed on 7 – 10 and 15 – 17 . Temperature dependent magnetic susceptibility measurements were performed on selective examples of all series, and confirmed them to be in the HS state over the range 6–300 K. DFT calculations were performed at BP86/def‐SV(P) and TPSSh/def2‐TZVPP level on all [Fe L 6]2+ complex cations and the neutral complexes 7 – 9 and 15 – 17 . Additionally the four homoleptic nickel(II) complexes [Ni L 6](ClO4)2 ( 11 : L = MeIm ; 12 : L = EtIm ; 13 : L = PrIm ; 14 : L = MeTz ) were synthesized and compounds 11 – 13 structurally characterized. UV/Vis/NIR spectroscopic measurements were carried out on all homoleptic iron(II) and nickel(II) complexes. The 10Dq values were determined to be in the range of 11547–11574 and 10471–10834 cm–1 for the iron(II) and nickel(II) complexes, respectively. 相似文献
14.
On the basis of density functional theory (DFT), the iron–nitrosyl complex Fe[Me3TACN](NO)(N3)2 (S = 3/2) is studied via the B3LYP hybrid method. Its Raman vibrational frequencies, atomic net charges, and spin densities are analyzed. The related complexes Fe(NH3) (n = 1, 2, and 3) are employed as reference compounds to determine the characteristics of the central iron. Our results indicate that the S = 3/2 spin ground state of Fe[Me3TACN](NO)(N3)2 is best described by the presence of FeII (S = 2) anti‐ferromagnetically coupled to NO0 (S = 1/2) yielding FeII[Me3TACN](NO0)(N)2. This is clearly different from the previous FeIII‐NO? theoretical assignment. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
15.
Caglar Remzi Becer Richard Hoogenboom David Fournier Ulrich S. Schubert 《Macromolecular rapid communications》2007,28(10):1161-1166
A novel tetradentate amine ligand namely N,N,N′,N″,N‴;,N‴;‐hexaoligo(ethylene glycol) triethylenetetramine (HOEGTETA) was employed in the homogenous ATRP of MMA in anisole using CuBr and CuBr2 as the catalyst and ethyl 2‐bromoisobutyrate (EBiB) as an initiator. The effect of the polymerization temperature and the various ratios of Cu(I) to Cu(II) were investigated in detail. Moreover, we demonstrated the ATRP of MMA by using only Cu(II) in the absence of any free radical initiator, reducing agent, or air. The ATRP of MMA with the use of only Cu(II) and HOEGTETA or N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) resulted in well‐defined PMMA.
16.
Xiaohuan Zhang Zhong Shen Litao Li Sen Zhang Guolin Lu Xiaoyu Huang 《Journal of polymer science. Part A, Polymer chemistry》2007,45(23):5509-5517
A series of well‐defined graft copolymers with a polyallene‐based backbone and polystyrene side chains were synthesized by the combination of living coordination polymerization of 6‐methyl‐1,2‐heptadien‐4‐ol and atom transfer radical polymerization (ATRP) of styrene. Poly(alcohol) with polyallene repeating units were prepared via 6‐methyl‐1,2‐heptadien‐4‐ol by living coordination polymerization initiated by [(η3‐allyl)NiOCOCF3]2 firstly, followed by transforming the pendant hydroxyl groups into halogen‐containing ATRP initiation groups. Grafting‐from route was employed in the following step for the synthesis of the well‐defined graft copolymer: polystyrene was grafted to the backbone via ATRP of styrene. The cleaved polystyrene side chains show a narrow molecular weight distribution (Mw/Mn = 1.06). This kind of graft copolymer is the first example of graft copolymer via allene derivative and styrenic monomer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5509–5517, 2007 相似文献
17.
Li‐Ping Yang Xue‐Hui Dong Cai‐Yuan Pan 《Journal of polymer science. Part A, Polymer chemistry》2008,46(23):7757-7772
The inverse star block copolymer, (poly(ε‐caprolactone)‐b‐polystyrene)2‐core‐(poly(ε‐caprolactone)‐b‐polystyrene)2, [(PCL‐PS)2‐core‐(PCL‐PS)2] has been successfully prepared by combination of atom transfer radical polymerization (ATRP), ring opening polymerization (ROP), and “Click Chemistry.” The synthesis includes the following five steps: (1) synthesis of a heterofunctional initiator with two ATRP initiating groups and two hydroxyl groups; (2) formation of (Br‐PS)2‐core‐(OH)2 via ATRP of styrene; (3) preparation of the (PCL‐PS)2‐core‐(OH)2 through “click” reaction of the α‐propargyl, ω‐acetyl terminated PCL with (N3‐PS)2‐core‐(OH)2 which was prepared by transformation of the terminal bromine groups in (Br‐PS)2‐core‐(OH)2 into azide groups; (4) the ROP of CL using (PCL‐PS)2‐core‐(OH)2 as macroinitiator to form (PCL‐PS)2‐core‐(PCL‐OH)2; and (5) preparation of the (PCL‐PS)2‐core‐(PCL‐PS)2 through the ATRP of styrene using (PCL‐PS)2‐core‐(PCL‐Br)2 as macroinitiator which was prepared by reaction of the terminal hydroxyl groups at the end of the PCL chains with 2‐bromoisobutyryl bromide. The characterization data support structures of the inverse star block copolymer and the intermediates. The differential scanning calorimeter results and polarized optical microscope observation showed that the intricate structure of the inverse star block copolymer greatly restricted the movement of the PS segments and PCL segments, resulted in the increase of the glass transition temperature of PS segments and the decrease of crystallization ability of PCL segments. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7757–7772, 2008 相似文献
18.
Shijie Ding Youqing Shen Maciej Radosz 《Journal of polymer science. Part A, Polymer chemistry》2004,42(14):3553-3562
The properties of a ligand, including molecular structure and substituents, strongly affect the catalyst activity and control of the polymerization in atom transfer radical polymerization (ATRP). A new tetradentate ligand, N,N′‐bis(pyridin‐2‐ylmethyl‐3‐hexoxo‐3‐oxopropyl)ethane‐1,2‐diamine (BPED) was synthesized and examined as the ligand of copper halide for ATRP of styrene (St), methyl acrylate (MA), and methyl methacrylate (MMA), and compared with other analogous linear tetrdendate ligands. The BPED ligand was found to significantly promote the activation reaction: the CuBr/BPED complex reacted with the initiators so fast that a large amount of Cu(II)Br2/BPED was produced and thus the polymerizations were slow for all the monomers. The reaction of CuCl/BPED with the initiator was also fast, but by reducing the catalyst concentration or adding CuCl2, the activation reaction could be slowed to establish the equilibrium of ATRP for a well‐controlled living polymerization of MA. CuCl/BPED was found very active for the polymerization of MA. For example, 10 mol% of the catalyst relatively to the initiator was sufficient to mediate a living polymerization of MA. The CuCl/BPED, however, could not catalyze a living polymerization of MMA because the resulting CuCl2/BPED could not deactivate the growing radicals. The effects of the ligand structures on the catalysis of ATRP are also discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3553–3562, 2004 相似文献
19.
Lifen Zhang Jie Miao Zhenping Cheng Xiulin Zhu 《Macromolecular rapid communications》2010,31(3):275-280
Initiators for continuous activator regeneration in atom transfer radical polymerization (ICAR ATRP) is a new technique for conducting ATRP. ICAR ATRP has many strong advantages over normal ATRP, such as forming the reductive transition metal species in situ using oxidatively stable transition metal species and a lower amount of metal catalyst in comparison with the normal ATRP system. In this work, the iron‐mediated ICAR ATRP of styrene and methyl methacrylate are reported for the first time using oxidatively stable FeCl3 · 6H2O as the catalyst in the absence of any thermal radical initiator. The kinetics of the polymerizations and effect of different polymerization conditions are studied. It is found that the polymerization of styrene can be conducted well even if the amount of iron(III ) is as low as 50 ppm.
20.
Jonas F. Schlagintweit Carolin Hintermeier Markus R. Anneser Eva‐Maria H. J. Esslinger Stefan Haslinger Fritz E. Kühn 《化学:亚洲杂志》2020,15(12):1896-1902
The synthesis of trans axially substituted mono‐ ( 1 a ) and bis(tert‐butylisocyanide) ( 1 b ) derivatives of the highly active homogeneous bio‐inspired iron(II) olefin epoxidation (pre‐)catalyst 1 bearing an equatorial macrocyclic tetra N‐heterocyclic carbene and two trans axial labile acetonitrile ligands is reported. NMR spectroscopy and SC‐XRD indicate a considerable π‐backdonation from the iron(II) centres to the isocyanide ligand(s). The impact of isocyanide substitution on the electronic features of the complexes is studied by cyclic voltammetry revealing a significant increase in half‐cell potential assignable to the reversible Fe(II)/Fe(III) redox couple with an increasing number of isocyanides as a result of their π‐accepting properties: E1/2=0.15 V ( 1 ), E1/2=0.35 V ( 1 a ), E1/2=0.44 V ( 1 b ). 相似文献