A series of cationic and neutral RuII complexes of the general formula [Ru(L)(X) (tBuCN)4]+X? and [Ru(L)(X)2(tBuCN)3)], that is, [Ru(CF3SO3){NCC(CH3)3}4(IMesH2)]+[CF3SO3]? ( 1 ), [Ru(CF3SO3){NCC(CH3)3}4(IMes)]+[CF3SO3]? ( 2 ), [RuCl{NCC(CH3)3}4(IMes)]+Cl? ( 3 ), [RuCl{NCC(CH3)3}4(IMesH2)+Cl?]/[RuCl2{NCC(CH3)3}3(IMesH2)] ( 4 ), and [Ru(NCO)2{NCC(CH3)3}3(IMesH2)] ( 5 ) (IMes=1,3‐dimesitylimidazol‐2‐ylidene, IMesH2=1,3‐dimesityl‐imidazolin‐2‐ylidene) have been synthesized and used as UV‐triggered precatalysts for the ring‐opening metathesis polymerization (ROMP) of different norborn‐2‐ene‐ and cis‐cyclooctene‐based monomers. The absorption maxima of complexes 1 – 5 were in the range of 245–255 nm and thus perfectly fit the emission band of the 254 nm UV source that was used for activation. Only the cationic RuII‐complexes based on ligands capable of forming μ2‐complexes such as 1 and 2 were found to be truly photolatent in ROMP. In contrast, complexes 3 – 5 could be activated by UV light; however, they also showed a low but significant ROMP activity in the absence of UV light. As evidenced by 1H and 13C NMR spectroscopy, the structure of the polymers obtained with either 1 or 2 are similar to those found in the corresponding polymers prepared by the action of [Ru(CF3SO3)2(IMesH2)(CH‐2‐(2‐PrO)‐C6H4)], which strongly suggest the formation of Ru‐based Grubbs‐type initiators in the course of the UV‐based activation process. Precatalysts that have the IMesH2 ligand showed significantly enhanced reactivity as compared with those based on the IMes ligand, which is in accordance with reports on the superior reactivity of IMesH2‐based Grubbs‐type catalysts compared with IMes‐based systems. 相似文献
A ring‐opening metathesis polymerization‐ (ROMP‐) based monolith was synthesized using a Grubbs' first generation catalyst. The living termini were used for surface grafting of norborn‐5‐ene‐2‐ylmethyl hexafluoroglutarate. The free carboxylic acid groups of the graft polymer were converted into the corresponding silver salt and reacted with the Grubbs–Hoveyda catalyst [RuCl2(CH (2‐iPrO )C6H4)(IMesH2)] (IMesH2 = 1,3‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene) to yield a stable heterogeneous version of this catalyst for use in ring‐closing metathesis (RCM) under continuous flow conditions.
The monolith‐supported Grubbs–Hoveyda catalyst. 相似文献
A dicationic ruthenium–alkylidene complex [Ru(dmf)3(IMesH2)(?CH‐2‐(2‐PrO)‐C6H4)][(BF4)2] ( 1 ; IMesH2=1,3‐dimesitylimidazolin‐2‐ylidene) has been prepared and used in continuous metathesis reactions by exploiting supported ionic‐liquid phase (SILP) technology. For these purposes, ring‐opening metathesis polymerization (ROMP)‐derived monoliths were prepared from norborn‐2‐ene, tris(norborn‐5‐ene‐2‐ylmethyloxy)methylsilane, and [RuCl2(PCy3)2(CHPh)] (Cy=cyclohexyl) in the presence of 2‐propanol and toluene and surface grafted with norborn‐5‐en‐2‐ylmethyl‐N,N,N‐trimethylammonium tetrafluoroborate ([NBE‐CH2‐NMe3][BF4]). Subsequent immobilization of the ionic liquid (IL), 1‐butyl‐2,3‐dimethylimidazolium tetrafluoroborate ([BDMIM][BF4]), containing ionic catalyst 1 created the SILP catalyst. The use of a second liquid transport phase, which contained the substrate and was immiscible with the IL, allowed continuous metathesis reactions to be realized. High turnover numbers (TONs) of up to 3700 obtained in organic solvents for the ring‐closing metathesis (RCM) of, for example, N,N‐diallyltrifluoroacetamide, diethyl diallylmalonate, diethyl di(methallyl)malonate, tert‐butyl‐N,N‐diallylcarbamate, N,N‐diallylacetamide, diphenyldiallylsilane, and 1,7‐octadiene, as well as in the self‐metathesis of methyl oleate, could be further increased by using biphasic conditions with [BDMIM][BF4]/heptane. Under continuous SILP conditions, TONs up to 900 were observed. Due to the ionic character of the initiator, catalyst leaching into the transport phase was very low (<0.1 %). Finally, the IL can, together with decomposed catalyst, be removed from the monolithic support by flushing with methanol. Upon reloading with [BDMIM][BF4]/ 1 , the recycled support material again qualified for utilization in continuous metathesis reactions. 相似文献
The new N‐heterocyclic carbene (NHC) precursors 4, ‐dicyano‐1, ‐dimesityl‐ ( 9 ) and 4, 5‐dicyano‐1, 3‐dineopentyl‐2‐(pentafluorophenyl)imidazoline ( 14 ) were synthesized. The structure of 9 could be determined by X‐ray crystallography. With the 2‐pentafluorophenyl‐substituted imidazolines 9 and 14 , the [AgCl(NHC)], [RhCl(COD)(NHC)], and [RhCl(CO)2(NHC)] complexes [NHC = 4, 5‐dicyano‐1, 3‐dimesitylimidazol‐2‐ylidene ( 3 ) and 4, 5‐dicyano‐1, 3‐dineopentylimidazol‐2‐ylidene ( 4 )] were obtained. Crystal structures of [AgCl( 3 )] ( 15 ), [RhCl(COD)( 3 )] ( 17 ), [RhCl(COD)( 4 )] ( 18 ), and [RhCl(CO)2( 3 )] ( 19 ) were solved and with the crystal data of 19 , the percent buried volume ( %Vbur) of 31.8(±0.1) % was determined for NHC 3 . Infrared spectra of the imidazolines 9 and 14 and of the complexes 15 – 20 were recorded and the CO stretching frequencies of complexes 19 and 20 were used to determine the Tolman electronic parameters of the newly obtained NHCs 3 (TEP: 2060 cm–1) and 4 (TEP: 2061 cm–1), thus proving that 1, 3‐substitution of maleonitrile‐NHCs does not have a significant effect for the high π‐acceptor strength of these carbenes. 相似文献
Complexes [{Ru(CO)Cl(PiPr3)2}2(μ‐2,5‐(CH?CH)2‐cC4H2E] (E=NR; R=C6H4‐4‐NMe2 ( 10 a ), C6H4‐4‐OMe ( 10 b ), C6H4‐4‐Me ( 10 c ), C6H5 ( 10 d ), C6H4‐4‐CO2Et ( 10 e ), C6H4‐4‐NO2 ( 10 f ), C6H3‐3,5‐(CF3)2 ( 10 g ), CH3 ( 11 ); E=O ( 12 ), S ( 13 )) are discussed. The solid state structures of four alkynes and two complexes are reported. (Spectro)electrochemical studies show a moderate influence of the nature of the heteroatom and the electron‐donating or ‐withdrawing substituents R in 10 a – g on the electrochemical and spectroscopic properties. The CVs display two consecutive one‐electron redox events with ΔE°′=350–495 mV. A linear relationship between ΔE°′ and the σp Hammett constant for 10 a–f was found. IR, UV/Vis/NIR and EPR studies for 10 +– 13 + confirm full charge delocalization over the {Ru}CH?CH‐heterocycle‐CH?CH{Ru} backbone, classifying them as Class III systems according to the Robin and Day classification. DFT‐optimized structures of the neutral complexes agree well with the experimental ones and provide insight into the structural consequences of stepwise oxidations. 相似文献
We have synthesized cis and trans N‐heterocyclic carbene (NHC) platinum(II) complexes bearing σ‐alkynyl ancillary ligands, namely [Pt(dbim)2(C?CR)2] [DBIM=N,N′‐didodecylbenzimidazoline‐2‐ylidene; R=C6H4F ( 4 ), C6H5 ( 5 ), C6H2(OMe)3 ( 6 ), C4H3S ( 7 ), and C6H4C?CC6H5 ( 8 )] and [Pt(ibim)2(C?CC6H5)2] ( 9 ) (ibim=N,N′‐diisopropylbenzimidazoline‐2‐ylidene), starting from [Pt(cod)(C?CR)2] (COD=cyclooctadiene) and 2 equivalents of [dbimH]Br ([ibimH]Br for complexes 9 ) in the presence of tBuOK and THF. Mechanistic investigations aimed at uncovering the cis to trans isomerization reaction have been performed on the representative cis complex 5 a [Pt(dbim)2(C?CC6H5)2] and revealed the isomerization to progress smoothly in good yield when 5 a was treated with catalytic amounts of [Pt(cod)(C?CR)2] at 75 °C in THF or when 5 a was heated at 200 °C in the solid state under an inert atmosphere. Detailed examination of the reactions points to the possible involvement, in a catalytic fashion, of a solvent‐stabilized PtII dialkyne complex in the former case and a Pt0 NHC complex in the latter case, for the transformation of the cis isomer to the corresponding trans complex. Thermal stability and the isomerization process in the solid state have been further investigated on the basis of TGA and DSC measurements. X‐ray diffraction studies have been carried out to confirm the solid‐state structures of 4 b , 5 a , 5 b , and 9 b . All of the synthesized dialkyne complexes 4 – 9 exhibit phosphorescence in solution, in the solid state at room temperature (RT), and also in frozen solvent glasses at 77 K. The emission wavelengths and quantum yields have been found to be highly tunable as a function of the alkynyl ligand. In particular, the trans isomer of complex 9 in a spin‐coated film (10 wt % in poly(methyl methacrylate), PMMA) exhibits a high phosphorescence quantum yield of 80 %, which is the highest reported for PtII‐based deep‐blue emitters. Experimental observations and time‐dependent density functional theory (TD‐DFT) calculations are strongly indicative of the emission being mainly governed by metal‐perturbed interligand (3IL) charge transfer. 相似文献
3‐[(3‐Aminopropyl)amino]‐1‐oxo‐1H‐naphtho[2,1‐b]pyran‐2‐carbaldehyde ( 10 ) was synthesized by nucleophilic substitution reaction of 2‐(3‐dimethylamino)‐1‐oxo‐1H‐naphtho[2,1‐b]pyran‐2‐carbaldehyde ( 9 ) and the monoprotected propane‐1,3‐diamine. The reaction with the unprotected reagent led to the unexpected 1‐(2‐hydroxynaphthalen‐1‐yl)‐2‐(tetrahydropyrimidin‐2(1H)‐ylidene)ethanone ( 6 ). Extension of this reaction to chromone 16 gave 1‐(2‐hydroxy‐3‐isopropyl‐6‐methylphenyl)‐2‐(tetrahydropyrimidin‐2(1H)‐ylidene)ethanone ( 7 ). The X‐ray crystal structures of 6 and 7 were also determined. 相似文献
Treatment of the osmabenzene [Os{CHC(PPh3)CHC(PPh3)CH} Cl2(PPh3)2]Cl ( 1 ) with excess 8‐hydroxyquinoline produces monosubstituted osmabenzene [Os{CH C(PPh3) CHC(PPh3)CH}(C9H6NO)Cl(PPh3)]Cl ( 2 ) or disubstituted osmabenzene [Os{CHC(PPh3)CHC(PPh3)CH} (C9H6NO)2]Cl ( 3 ) under different reaction conditions. Osmabenzene 2 evolves into cyclic η2‐allene‐coordinated complex [Os{CH?C(PPh3)CH=(η2‐C?CH2)}(C9H6NO)(PPh3)2]Cl ( 4 ) in the presence of excess PPh3 and NaOH, presumably involving a P? C bond cleavage of the metallacycle. Reaction of 4 with excess 8‐hydroxyquinoline under air affords the SNAr product [(C9H6NO)Os{CHC(PPh3)CHCHC} (C9H6NO)(PPh3)]Cl ( 5 ). Complex 4 is fairly reactive to a nucleophile in the presence of acid, which could react with water to give carbonyl complex [Os{CH?C(PPh3)CH?CH2}(C9H6NO) (CO)(PPh3)2]Cl ( 6 ). Complex 4 also reacts with PPh3 in the presence of acid and results in a transformation to [Os {CHC(PPh3)CHCHC}(C9H6NO)Cl (PPh3)2]Cl ( 7 ) and [Os{CH?C(PPh3) CH=(η2‐C?CH(PPh3))}(C9H6NO) Cl(PPh3)]Cl ( 8 ). Further investigation shows that the ratio of 7 and 8 is highly dependent on the amount of the acid in the reaction. 相似文献
The synthesis of a novel series of the intermediates N2(N3)‐[1‐alkyl(aryl/heteroaryl)‐3‐oxo‐4,4,4‐trifluoroalk‐1‐en‐1‐yl]‐2‐aminopyridines [F3CC(O)CH?CR1(2? NH?C5H3N)] and 2,3‐diaminopyridines [F3CC(O)CH?CR1(2‐NH2‐3‐NH? C5H3N)], where R1 = H, Me, C6H5, 4‐FC6H4, 4‐CIC6H4, 4‐BrC6H4, 4‐CH3C6H4, 4‐OCH3C6H4, 4,4′‐biphenyl, 1‐naphthyl, 2‐thienyl, 2‐furyl, is reported. The corresponding series of 2‐aryl(heteroaryl)‐4‐trifluoromethyl‐3H‐pyrido[2,3‐b][1,4]diazepin‐4‐ols obtained from intramolecular cyclization reaction of the respective trifluoroacetyl enamines or from the direct cyclocondensation reaction of 4‐methoxy‐1,1,1‐trifluoroalk‐3‐en‐2‐ones with 2,3‐diaminopyridine, under mild conditions, is also reported. 相似文献
The five‐coordinate ruthenium N‐heterocyclic carbene (NHC) hydrido complexes [Ru(IiPr2Me2)4H][BArF4] ( 1 ; IiPr2Me2=1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene; ArF=3,5‐(CF3)2C6H3), [Ru(IEt2Me2)4H][BArF4] ( 2 ; IEt2Me2=1,3‐diethyl‐4,5‐dimethylimidazol‐2‐ylidene) and [Ru(IMe4)4H][BArF4] ( 3 ; IMe4=1,3,4,5‐tetramethylimidazol‐2‐ylidene) have been synthesised following reaction of [Ru(PPh3)3HCl] with 4–8 equivalents of the free carbenes at ambient temperature. Complexes 1 – 3 have been structurally characterised and show square pyramidal geometries with apical hydride ligands. In both dichloromethane or pyridine solution, 1 and 2 display very low frequency hydride signals at about δ ?41. The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct [Ru(IMe4)4(MeCN)H][BArF4], 4 . The reactivity of 1 – 3 towards H2 and N2 depends on the size of the N‐substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts with both H2 and N2 only at low temperature and incompletely, while 3 affords [Ru(IMe4)4(η2‐H2)H][BArF4] ( 7 ) and [Ru(IMe4)4(N2)H][BArF4] ( 8 ) in quantitative yield at room temperature. CO shows no selectivity, reacting with 1 – 3 to give [Ru(NHC)4(CO)H][BArF4] ( 9 – 11 ). Addition of O2 to solutions of 2 and 3 leads to rapid oxidation, from which the RuIII species [Ru(NHC)4(OH)2][BArF4] and the RuIV oxo chlorido complex [Ru(IEt2Me2)4(O)Cl][BArF4] were isolated. DFT calculations reproduce the greater ability of 3 to bind small molecules and show relative binding strengths that follow the trend CO ? O2 > N2 > H2. 相似文献
Diffraction‐quality single crystals of two gold(I) complexes, namely bis(1,3‐dimesityl‐4,5‐naphthoquinoimidazol‐2‐ylidene)gold(I) chloride benzene monosolvate, [Au(C29H26N2O2)2]Cl·C6H6 or [(NQMes)2Au]Cl·C6H6, 2 , and bis(1,3‐dimesityl‐4,5‐naphthoquinoimidazol‐2‐ylidene)gold(I) dichloridoaurate(I) dichloromethane disolvate, [Au(C29H26N2O2)2][AuCl2]·2CH2Cl2 or [(NQMes)2Au][AuCl2]·2CH2Cl2, 4 , were isolated and studied with the aid of single‐crystal X‐ray diffraction analysis. Compound 2 crystallizes in a monoclinic space group C2/c with eight molecules in the unit cell, while compound 4 crystallizes in the triclinic space group P with two molecules in the unit cell. The crystal lattice of compound 2 reveals C—H…Cl? interactions that are present throughout the entire structure representing head‐to‐tail contacts between the aromatic (C—H) hydrogens of naphthoquinone and Cl? counter‐ions. Compound 4 stacks with the aid of short interactions between a naphthoquinone O atom of one molecule and the mesityl methyl group of another molecule along the a axis, leading to a one‐dimensional strand that is held together by strong π–η2 interactions between the imidazolium backbone and the [AuCl2]? counter‐ion. The bond angles defined by the AuI atom and two carbene C atoms [C(carbene)—Au—C(carbene)] in compounds 2 and 4 are nearly rectilinear, with an average value of ~174.1 [2]°. Though 2 and 4 share the same cation, they differ in their counter‐anion, which alters the crystal lattice of the two compounds. The knowledge gleaned from these studies is expected to be useful in understanding the molecular interactions of 2 and 4 under physiological conditions. 相似文献
Ru‐Catalyzed olefin cross‐metathesis (CM) has been successfully applied to the synthesis of several phytyl derivatives ( 2b, 2d – f, 3b ) with a trisubstituted C?C bond, as useful intermediates for an alternative route to α‐tocopheryl acetate (vitamin E acetate; 1b ) (Scheme 1). Using the second‐generation Grubbs catalyst RuCl2(C21H26N2)(CHPh)PCy3 (Cy = cyclohexyl; 4a ) and Hoveyda–Grubbs catalyst RuCl2(C21H26N2){CH‐C6H4(O‐iPr)‐2} ( 4b ), the reactions were performed with various C‐allyl ( 5a – f, 7a,b ) and O‐allyl ( 8a – d ) derivatives of trimethylhydroquinone‐1‐acetate as substrates. 2,6,10,14‐Tetramethylpentadec‐1‐ene ( 6a ) and derivatives 6c – e of phytol ( 6b ) as well as phytal ( 6f ) were employed as olefin partners for the CM reactions (Schemes 2 and 5). The vitamin E precursors could be prepared in up to 83% isolated yield as (E/Z)‐mixtures. 相似文献
The reactivities of two 20‐membered macrocyclic ligands, each containing two N‐heterocyclic carbene (NHC) and two amine groups, towards [IrCl(COD)]2 (COD is cycloocta‐1,5‐diene) were investigated. Macrocycles containing imidazolin‐2‐ylidene groups formed the monometallic complex [(1,2,5,6‐η)‐cycloocta‐1,5‐diene](5,16‐dibenzyl‐1,5,9,12,16,20‐hexaazatricyclo[18.2.1.19,12]tetracosa‐10,21‐dien‐21,22‐diylidene)iridium(I) bromide dichloromethane monosolvate, [Ir(C8H12)(C32H42N6)]Br·CH2Cl2, 2a . The structure of iridium complex 2a at 100 K has triclinic P symmetry. The ligand in 2a coordinates to the Ir center through the NHC moieties in a cis fashion. Additionally, the ligand adopts an umbrella‐like structure that appears to envelope the Ir center. The structure displays C—H…Br interactions. Macrocycles containing benzimidazolin‐2‐ylidene groups formed the bimetallic complex [μ‐5,20‐dibenzyl‐1,5,9,16,20,24‐hexaazapentacyclo[22.6.1.19,16.010,15.025,30]dotriaconta‐10(15),11,13,25(30),26,28‐hexaene‐31,32‐diylidene]bis{bromido[(1,2,5,6‐η)‐cycloocta‐1,5‐diene]iridium(I)}, [Ir2Br2(C8H12)2(C40H46N6)], 2b . The structure of complex 2b at 100 K has orthorhombic Pbca symmetry. Each NHC moiety in 2b coordinates in a monodentate fashion to an Ir(COD) fragment. The structure exhibits disorder of the main molecule. This disorder is found in the portion of the macrocycle containing an amine group. This structure also displays C—H…Br interactions. Finally, the structure of the hexafluorophosphate salt of the imidazolin‐2‐ylidene‐containing macrocycle, namely 5,16‐dibenzyl‐1λ5,5,9,12λ5,16,20‐hexaazatricyclo[18.2.1.19,12]tetracosa‐1(23),10,12(24),21‐tetraene‐1,12‐diium bis(hexafluorophosphate), C32H44N62+·2PF6?, 1c , was determined. The structure of macrocycle 1c at 100 K has triclinic P symmetry and was found to contain C—H…F interactions. 相似文献
The 1‐(2,3,4,5,1′,2′,3′,4′‐octamethylferrocen‐1‐yl)‐3‐(ruthenocenyl)allylium cation readily undergoes one‐electron oxidation to a dication in which an octamethylferrocenium moiety is bridged by a vinylene group to a [(η6‐fulvene)(η5‐cyclopentadienyl)ruthenium]+ moiety. In the title compound, 1‐(2,3,4,5,1′,2′,3′,4′‐octamethylferrocen‐1‐yl)‐3‐(ruthenocenylidene)prop‐1‐enium(2+) bis(tetrafluoroborate), [FeRu(C5H5)(C9H13)(C17H19)](BF4)2, the C—C bond lengths in the bridge (average for two independent molecules) are, starting from the ipso octamethylferrocenium carbon and ending at the exo carbon of the coordinated fulvene, 1.455 (6), 1.344 (3) and 1.449 (8) Å, indicating a localized electronic structure. 相似文献
The title compound, [(S)‐2‐(anilinomethyl)pyrrolidine‐N,N′]‐chloro(η6‐para‐cymene)ruthenium(II) chloride, [RuCl‐(C10H14)(C11H16N2)]Cl, has been synthesized by the reaction of [RuCl2(p‐cymene)]2 (p‐cymene is para‐isopropyltoluene) with (S)‐2‐(anilinomethyl)pyrrolidine in triethylamine/2‐propanol. The Ru atom is in a pseudo‐tetrahedral environment coordinated by a chloride ligand, the aromatic hydrocarbon is linked in a η6 manner and the amine is linked via its two N atoms. The chloride anion is involved in hydrogen bonding with the diamine moieties through N—H?Cl interactions, with N?Cl distances of 3.273 (4) and 3.352 (4) Å. 相似文献