Phosphine (oxide)‐(thio) phenolate palladium complexes: Synthesis,characterization and (co)polymerization of norbornene

A series of palladium complexes ( 2a–2g ) ( 2a : [6‐^tBu‐2‐PPh₂‐C₆H₃O]PdMe(Py); 2b : [6‐C₆F₅–2‐PPh₂‐C₆H₃O]PdMe(Py); 2c : [6‐^tBu‐2‐PPh^tBu‐C₆H₃O]PdMe(Py); 2d : [2‐PPh^tBu‐C₆H₄O] PdMe(Py); 2e : [6‐SiMe₃–2‐PPh₂‐C₆H₃O]PdMe(Py); 2f : [2‐^tBu‐6‐(Ph₂P=O)‐C₆H₃O]PdMe(Py); 2g : [6‐SiMe₃–2‐(Ph₂P=O)‐C₆H₃S]PdMe(Py)) bearing phosphine (oxide)‐(thio) phenolate ligand have been efficiently synthesized and characterized. The solid‐state structures of complexes 2d , 2f and 2g have been further confirmed by single‐crystal X‐ray diffraction, which revealed a square‐planar geometry of palladium center. In the presence of B(C₆F₅)₃, these complexes can be used as catalysts to polymerize norbornene (NB) with relatively high yields, producing vinyl‐addition polymers. Interestingly, 2a /B(C₆F₅)₃ system catalyzed the polymerization of NB in living polymerization manner at high temperature (polydispersity index 1.07, M_n up to 1.5 × 10⁴). The co‐polymerization of NB and polar monomers was also studied using catalysts 2a and 2f . All the obtained co‐polymers could dissolve in common solvent.     

Stoichiometric and Catalytic Aryl−Cl Activation and Borylation using NHC-stabilized Nickel(0) Complexes

NHC-nickel (NHC=N-heterocyclic carbene) complexes are efficient catalysts for the C−Cl bond borylation of aryl chlorides using NaOAc as a base and B₂pin₂ (pin=pinacolato) as the boron source. The catalysts [Ni₂(ICy)₄(μ-(η²:η²)-COD)] ( 1 , ICy=1,3-dicyclohexylimidazolin-2-ylidene; COD=1,5-cyclooctadiene), [Ni(ICy)₂(η²-C₂H₄)] ( 2 ), and [Ni(ICy)₂(η²-COE)] ( 3 , COE=cyclooctene) compare well with other nickel catalysts reported previously for aryl-chloride borylation with the advantage that no further ligands had to be added to the reaction. Borylation also proceeded with B₂neop₂ (neop=neopentylglycolato) as the boron source. Stoichiometric oxidative addition of different aryl chlorides to complex 1 was highly selective affording trans-[Ni(ICy)₂(Cl)(Ar)] (Ar=4-(F₃C)C₆H₄, 11 ; 4-(MeO)C₆H₄, 12 ; C₆H₅, 13 ; 3,5-F₂C₆H₃, 14 ).     

Amidrazones. VII. Formation of s-triazines by thermolysis of N1-benzyl-substituted amidrazone ylides

The preparation of ylides of the general structure is described. Thermolysis of 14a (R = CH₃, R' = H, Ar = C₆H₅) gave dimethylamine and 2,4-dimethyl-6-phenyl-s-triazine. Thermolysis of ylides 14b (R = C₆H₅; R' = CH₃, Ar = C₆H₅) and 14c (R = C₆H₅, R' = CH₃, Ar = p-tolyl) gave dimethylamine, ArCH = NCH₃ and 1-methyl-2-Ar-4,6-diphenyl-1,2-dihydro-s-triazines ( 19a,b ). Triazines 19a and 19b were also prepared by condensation of N-methylbenzamidine with benzaldehyde and p-tolualdehyde, respectively. Thermolysis of 14d (R = C₆H₅, R¹ = CH₂C₆H₅,Ar = C₆H₅) gave 1-benzyl-2,4,6-triphenyl-1,2-dihydro-s-triazine ( 19c ) and N-benzylidenebenzylamine. Mechanistic aspects of these reactions are discussed.     

Synthesis and characterization of aluminum(III) and tin(II) complexes supported by diiminophosphinate ligands and their application in ring‐opening polymerization catalysis of ε‐caprolactone

A series of Al(III) and Sn(II) diiminophosphinate complexes have been synthesized. Reaction of Ph(ArCH₂)P(?NBu^t)NHBu^t (Ar = Ph, 3 ; Ar = 8‐quinolyl, 4 ) with AlR₃ (R = Me, Et) gave aluminum complexes [R₂Al{(NBu^t)₂P(Ph)(CH₂Ar)}] (R = Me, Ar = Ph, 5 ; R = Me, Ar = 8‐quinolyl, 6 ; R = Et, Ar = Ph, 7 ; R = Et, Ar = quinolyl, 8 ). Lithiated 3 and 4 were treated with SnCl₂ to afford tin(II) complexes [ClSn{(NBu^t)₂P(Ph)(CH₂Ar)}] (Ar = Ph, 9 ; Ar = 8‐quinolyl, 10 ). Complex 9 was converted to [(Me₃Si)₂NSn{(NBu^t)₂P(Ph)(CH₂Ph)}] ( 11 ) by treatment with LiN(SiMe₃)₂. Complex 11 was also obtained by reaction of 3 with [Sn{N(SiMe₃)₂}₂]. Complex 9 reacted with [LiOC₆H₄Bu^t‐4] to yield [4‐Bu^tC₆H₄OSn{(NBu^t)₂P(Ph)(CH₂Ph)}] ( 12 ). Compounds 3–12 were characterized by NMR spectroscopy and elemental analysis. The structures of complexes 6 , 10 , and 11 were further characterized by single crystal X‐ray diffraction techniques. The catalytic activity of complexes 5–8 , 11 , and 12 toward the ring‐opening polymerization of ε‐caprolactone (CL) was studied. In the presence of BzOH, the complexes catalyzed the ring‐opening polymerization of ε‐CL in the activity order of 5 > 7 ≈ 8 > 6 ? 11 > 12 , giving polymers with narrow molecular weight distributions. The kinetic studies showed a first‐order dependency on the monomer concentration in each case. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4621–4631, 2006     

Organoaluminum Compounds as Catalysts for Monohydroboration of Carbodiimides

The effective catalytic activity of organoaluminum compounds for the monohydroboration of carbodiimides has been demonstrated. Two aluminum complexes, 2 and 3 , were synthesized and characterized. The efficient catalytic performances of four aluminum hydride complexes L¹AlH₂ (L¹=HC(CMeNAr)₂, Ar=2,6-Et₂C₆H₃; 1 ), L²AlH₂(NMe₃) (L²=o-C₆H₄F(CH=N-Ar), Ar=2,6-Et₂C₆H₃; 2 ), L³AlH (L³=2,6-bis(1-methylethyl)-N-(2-pyridinylmethylene)phenylamine; 3 ), and L⁴AlH(NMe₃) (L⁴=o-C₆H₄(N-Dipp)(CH=N-Dipp), Dipp=2,6-iPr₂C₆H₃; 4 ), and an aluminum alkyl complex L¹AlMe₂ ( 5 ) were used for the monohydroboration of carbodiimides investigated under solvent-free and mild conditions. Compounds 1 – 3 and 5 can produce monohydroborated N-borylformamidine, whereas 4 can afford the C-borylformamidine product. A suggested mechanism of this reaction was explored, and the aluminum formamidinate compound 6 was characterized by single-crystal X-ray, also a stoichiometric reaction was investigated.     

Synthesis of β-Ketoiminato Copper(II) Complexes and Their Use in Copper Deposition

The template synthesis of ethylenediamine ( 1 ) with 2-acetylcyclopentanone ( 2 ) and [Cu(OAc)₂ · H₂O] ( 5 ) produced [Cu(1-(2-cC₅H₆(O))C(Me)NCH₂)₂)] ( 6 ) in 82 % yield. Reaction of 5 with bis(benzoylacetone)diethylenetriamine ( 7 , = L H)^[1] gave [Cu(μ-OAc)( L )(H₂O)]₂ ( 8 ). The solid-state structures of 6 and 8 were determined confirming that 8 possesses intra- and intermolecular hydrogen bonds resulting in a dimer formation. The thermal behavior of 6 – 8 was studied by TG and TG-MS. Under oxygen CuO was formed, whereas under Ar Cu/Cu₂O ( 6 ) or Cu ( 8 ) was obtained. Complex 6 was used as CVD precursor for Cu and Cu-oxide deposition (substrate temp., 400–500 °C, N₂, 60 mL · min^–1; O₂, 60 mL · min^–1; pressure, 0.87–1.5 mbar). The as-obtained deposits show separated particles of different appearance at the substrate surface as evidenced by SEM. Non-volatile 8 was applied as spin-coating precursor for Cu and CuO formation [conc. 0.25 mol · L^–1; volume 0.2 mL; 3000 rpm; depos. time 2 min; heating rate 50 K · min^–1; holding time 60 min (Ar), 120 min (air) at 800 °C]. The samples on silicon consist of granulated particles (Ar) or are non-dense with a grainy topography (air). EDX and XPS measurements confirmed the formation of Cu (Ar) or CuO (O₂) with up to 13 mol-% C impurity.     

Syntheses,crystal structures,and electrochemistry of novel Fe2SN and FeSN carbonyl complexes with pendant bases

Reactions of Fe₂(CO)₉ with thioacylhydrazones ArCH=NNHCSPh in THF afford Fe₂(CO)₆(μ-κ²S:κ²N-PhC(S)=NNCHArCHArN(CHAr)N=CSPh) (1, Ar?=?C₆H₅; 3, Ar?=?4-CH₃C₆H₄) and Fe(CO)₃(κ²S:N-PhC(=S)NHNCHArCHArN(CHAr)N=CSPh) (2, Ar?=?C₆H₅; 4, Ar?=?4-CH₃C₆H₄). They have been characterized by elemental analyses, IR, ¹H NMR, and ¹³C NMR and structurally determined by X-ray crystallography. Electrochemical studies reveal that when using HOAc as a proton source, they exhibit high catalytic H₂-production.     

Efficient introduction of aromatic vinyl group by incorporation of divinylbiphenyl,p‐divinylbenzene in syndiospecific styrene polymerization using aryloxo‐modified half‐titanocene catalysts

An efficient introduction of aromatic vinyl group into syndiotactic polystyrene has been achieved by incorporation of 3,3′‐divinylbiphenyl, p‐divinylbenzene (DVB) in syndiospecific styrene polymerization using aryloxo‐modified half‐titanocenes, Cp′TiCl₂(O‐2,6‐ⁱPr₂C₆H₃) (Cp′ = ^tBuC₅H₄, 1,2,4‐Me₃C₅H₂), in the presence of MAO. The resultant polymers possessed high molecular weights with uniform molecular weight distributions, and the DVB contents could be varied by the initial feed molar ratios (6–23 mol %) without decrease in the M_n values. The syndiotactic stereo‐regularity and presence of the vinyl groups were confirmed by NMR spectra. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1902–1907     

Phosphine-Stabilized Pnictinidenes

The reaction of the intramolecular germylene-phosphine Lewis pair (o-PPh₂)C₆H₄GeAr* ( 1 ) with Group 15 element trichlorides ECl₃ (E=P, As, Sb) was investigated. After oxidative addition, the resulting compounds (o-PPh₂)C₆H₄(Ar*)Ge(Cl)ECl₂ ( 2 : E=P, 3 : E=As, 4 : E=Sb) were reduced by using sodium metal or LiHBEt₃. The molecular structures of the phosphine-stabilized phosphinidene (o-PPh₂)C₆H₄(Ar*)Ge(Cl)P ( 5 ), arsinidene (o-PPh₂)C₆H₄(Ar*)Ge(Cl)As ( 6 ) and stibinidene (o-PPh₂)C₆H₄(Ar*)Ge(Cl)Sb ( 7 ) are presented; they feature a two-coordinate low-valent Group 15 element. After chloride abstraction, a cyclic germaphosphene [(o-PPh₂)C₆H₄(Ar*)GeP] [B(C₆H₃(CF₃)₂)₄] ( 8 ) was isolated. The ³¹P NMR data of the germaphosphene were compared with literature examples and analyzed by quantum chemical calculations. The phosphinidene was treated with [iBu₂AlH]₂, and the product of an Al−H addition to the low-valent phosphorus atom (o-PPh₂)C₆H₄(Ar*)Ge(H)P(H)Al(C₄H₉)₂ ( 9 ) was characterized.     

Synthesis and characterization of novel neutral nickel complexes bearing fluorinated salicylaldiminato ligands and their catalytic behavior for vinylic polymerization of norbornene

A series of salicylaldimine‐based neutral Ni(II) complexes (3a–j) [ArN = CH(C₆H₄O)]Ni(PPh₃)Ph [3a, Ar = C₆H₅; 3b, Ar = C₆H₄F(o); 3c, Ar = C₆H₄F(m); 3d, Ar = C₆H₄F(p); 3e, Ar = C₆H₃F₂(2,4); 3f, Ar = C₆H₃F₂(2,5); 3g, Ar = C₆H₃F₂(2,6); 3h, Ar = C₆H₃F₂(3,5); 3i, Ar = C₆H₂F₃(3,4,5); 3j, Ar = C₆F₅] have been synthesized in good yield, and the structures of complexes 3a and 3i have been confirmed by X‐ray crystallographic analysis. Using modified methylaluminoxane as a cocatalyst, these neutral Ni(II) complexes exhibited high catalytic activities for the vinylic polymerization of norbornene. It was observed that the strong electron‐withdrawing effect of the fluorinated salicylaldiminato ligand was able to significantly increase the catalyst activity for vinylic polymerization of norbornenes. In addition, catalyst activity, polymer yield and polymer molecular weight can also be controlled over a wide range by the variation of reaction parameters such as Al:Ni ratio, norbornene:catalyst ratio, monomer concentration, polymerization temperature and time. Copyright © 2008 John Wiley & Sons, Ltd.     

Latent cationic palladium(II) phosphine carboxylate complexes for norbornene polymerization

The catalytic efficacy of trans‐[(R₃P)₂Pd(O₂CR′)(LB)][B(C₆F₅)₄] ( 1 ) (LB = Lewis base) and [(R₃P)₂Pd(κ²‐O,O‐O₂CR′)][B(C₆F₅)₄] ( 2 ) for mass polymerization of 5‐n‐butyl‐2‐norbornene (Butyl‐NB) was investigated. The nature of PR₃ and LB in 1 and 2 are the most critical components influencing catalytic activity/latency for the mass polymerization of Butyl‐NB. Further, it was shown that 1 is in general more latent than 2 in mass polymerization of Butyl‐NB. 5‐n‐Decyl‐2‐norbornene (Decyl‐NB) was subjected to solution polymerization in toluene at 63(±3) °C in the presence of several of the aforementioned palladium complexes as catalysts and the polymers obtained were characterized by gel permeation chromatography. Cationic trans‐[(R₃P)₂PdMe(MeCN)][B(C₆F₅)₄] [R = Cy ( 3a ), and ⁱPr ( 3b )] and trans‐[(R₃P)₂PdH (MeCN)][B(C₆F₅)₄] [R = Cy ( 4a ), and ⁱPr ( 4b )], possible products from thermolysis of trans‐[(R₃P)₂Pd(O₂CMe)(MeCN)][B(C₆F₅)₄] [R = Cy ( 1a ) and ⁱPr ( 1g )], as well as trans‐[(R₃P)₂Pd(η³‐C₃H₅)][B(C₆F₅)₄] [R = Cy ( 5a ), and ⁱPr ( 5b )], were also examined as catalysts for solution polymerization of Decyl‐NB. A maximum activity of 5360 kg/(molPd h) of 2a was achieved at a Decyl‐NB/Pd: 26,700 ratio which is slightly better than that achieved with 5a [activity: 5030 kg/(molPd h)] but far less compared with 4a [activity: 6110 kg/(molPd h)]. Polydispersity values indicate a single highly homogeneous character of the active catalyst species. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 103–110, 2009     

Thermodynamic Enantioface-Binding Selectivities of Monosubstituted Alkenes to a Highly Discriminating Chiral Transition -Metal Lewis Acid; equilibration of diastereoisomeric (cyclopentadienyl)(alkene)(nitrosyl)(triphenylphosphine)rhenium complexes ([Re(η5–C5H5)(CH2 = CHR)(NO) (PPh3)]+BF)

Reactions of monosubstituted alkenes RCH = CH₂ and [Re(η⁵–C₅H₅)(CH₂Cl₂) (NO)(PPh₃)]⁺BF give complexes ([Re(η⁵–C₅H₅))(CH₂?CHR)(NO) (PPh₃)]⁺BF ( 1a–g ) in 63–99% yields as mixtures of (RS,SR)- and (RR,SS)-diastereoisomers ( 1a (R = Me), 66:34; 1b (R = Pr), 63:37; 1c (R = PhCH₂), 70:30; 1d (R = Ph), 75:25; 1e (R = i-Pr), 64:36; 1f (R = t-Bu), 84:16; 1g (R = Me₃Si), 69:31; Scheme 2). These differ in the C?C enantioface bound to the chiral Re fragment. In most cases, the analogous reactions of RCH?CH₂ and [Re(η⁵–C₅H₅) (C₆H₅Cl)(NO)(PPh₃)]⁺ BF give comparable results. When 1a – e , g are heated in PhCl at 95–100°, equilibration to 96:4, 97:3, 97:3, 90:10, > 99:< 1, and > 99:< 1 (RS,SR)/(RR,SS) mixtures occurs (79–99% recoveries; Tables 1 and 2). Thus, thermodynamic enantioface-binding selectivities are much higher than kinetic binding selectivities. This phenomenon is analyzed in detail. A crystal structure of (RS,SR)- 1e (monoclinic, P2₁/c, a = 10.256(1) Å. b = 17.191(1) Å, c = 16.191(1) Å, β = 101.04(1)°, Z = 4) shows that the Re–C(1)–C(2) plane (see Fig.2) is nearly coincident with the Re–P bond (angle 15°), and that the i-Pr group is ‘syn’ to the nitrosyl ligand.     

Aryl(pentafluorphenyl)iodoniumtetrafluoroborate: allgemeine Synthesemethode,typische Eigenschaften und strukturelle Gemeinsamkeiten

Pentafluorophenyliodine(III) Compounds. 4 [1] Aryl(pentafluorophenyl)iodoniumtetrafluoroborates: General Method of Synthesis, Typical Properties, and Structural Features Aryl(pentafluorophenyl)iodoniumtetrafluoroborates [Ar′Ar″I][BF₄] (Ar′ = C₆F₅, Ar″ = C₆H₅, o‐C₆H₄F, m‐C₆H₄F, p‐C₆H₄F, 2,6‐C₆H₃F₂, 3,5‐C₆H₃F₂, 2,4,6‐C₆H₂F₃, 3,4,5‐C₆H₂F₃, C₆F₅) are prepared in good yields and high purity by the reaction of C₆F₅IF₂ with Ar″BF₂ in CH₂Cl₂. This convenient method can be applied generally to many iodonium compounds. Thermal and spectroscopic properties (¹H, ¹³C, ¹⁹F NMR, IR, Raman) are reported and discussed. The solid state structures of six iodonium compounds show significant cation‐anion interactions which result in two different arrangements: a dimer with a 8‐membered ring or polymers with infinite zigzag chains. Ab initio calculations on prototypes of aryliodonium cations show relations between the kind of the aryl group (C₆H₅ vs. C₆F₅) and structural parameters as well as charges. By means of ¹⁹F NMR the σ_I‐ and σ_R‐constants of the [C₆F₅I]⁺‐substituent are determined.     

Nickel(II) tellurolates: preparative,spectral and electrochemical studies

Summary Complexes of the type [NiCl(TeAr)(DPPE)] (1) and [Ni-(TeAr)₂(DPPE)] (2) [Ar = Ph, C₆H₄Me-4, C₆H₄OMe-4 or C₆H₄OEt-4; DPPE = 1, 2-bis(diphenylphosphino)-ethane] were prepared from [NiCl₂(DPPE)] and NaTeAr (generated in situ) in EtOH-C₆H₆. Their structures were established by elemental analysis, conductance and molecular weight measurements and i.r., electronic, ¹H and ³¹ Pn.m.r. spectra. The analytical and spectroscopic data are consistent with a square planar geometry around nickel in (1) and (2). Metathetical reactions between (1) (Ar = C₆H₄OMe-4) and NaX (X = I or Br) in MeOH give [NiX(TeAr)(DPPE)] (3). Electrochemical studies of (1) and (2) using c.v. indicate an irreversible cathodic peak (ca. –0.76 to 0.86 V) corresponding to reduction of nickel(II) to nickel(0) and an irreversible anodic peak (ca. –0.04 to 0.37 V) for oxidation of the tellurolate ligand.     

Synthesis of poly(1‐chloro‐2‐arylacetylene)s with high cis‐content and examination of their absorption/emission properties

A series of 1‐chloro‐2‐arylacetylenes [Cl‐C?C‐Ar, Ar = C₆H₅ ( 1 ), C₆H₄‐p‐i Pr ( 2 ), C₆H₄‐p‐Oi Pr ( 3 ), C₆H₄‐p‐NHC(O)Ot Bu ( 4 ), and C₆H₄‐o‐i Pr ( 5 )] were polymerized using (tBu₃P)PdMeCl/silver trifluoromethanesulfonate (AgOTf) and MoCl₅/SnBu₄ catalysts. The corresponding polymers [poly( 1 )–poly( 5 )] with weight‐average molecular weights of 6,500–690,000 were obtained in 10–91% yields. THF‐insoluble parts, presumably high‐molecular weight polymers, were formed together with THF‐soluble polymers by the Pd‐catalyzed polymerization. The Pd catalyst polymerized nonpolar monomers 1 and 2 to give the polymers in yields lower than the Mo catalyst, while the Pd catalyst polymerized polar monomers 3 and 4 to give the corresponding polymers in higher yields. The ¹H NMR and UV–vis absorption spectra of the polymers indicated that the cis‐contents of the Pd‐based polymers were higher than those of the Mo‐based polymers, and the conjugation length of the Pd‐based polymers was shorter than that of the Mo‐based polymers. Pd‐based poly( 5 ) emitted fluorescence most strongly among poly( 1 )–poly( 5 ). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 382–388     

Ni(II) and Pd(II) complexes bearing novel bis(β‐ketoamino) ligand and their catalytic activity toward copolymerization of norbornene and 5‐norbornene‐2‐yl acetate combined with B(C6F5)3

Two complexes Mt{C₁₀H₈(O)C[N(C₆H₅)]CH₃}₂ [Mt = Ni(II); Mt = Pd(II)] were synthesized, and the solid‐state structures of the complexes have been determined by single‐crystal X‐ray diffractions. Homopolymerization of norbornene (NB) and copolymerization of NB and 5‐norbornene‐2‐yl acetate (NB‐OCOCH₃) were carried out in toluene with both the two complexes mentioned above in combination with B(C₆F₅)₃. Both the catalytic systems exhibited high activity toward the homopolymerization of NB (as high as 2.7 × 10⁵ g_polymer/mol_Ni h, for Ni(II)/B(C₆F₅)₃ and 2.1 × 10⁵ g_polymer/mol_Pd h for Pd(II)/B(C₆F₅)₃, respectively.). Although the Pd(II)/B(C₆F₅)₃ shows very lower activity toward the copolymerization of NB with NB‐OCOCH₃, Ni(II)/B(C₆F₅)₃ shows a high activity and produces the addition‐type copolymer with relatively high molecular weights (MWs; 1.80–2.79 × 10⁵ g/mol) as well as narrow MW distribution (1.89–2.30). The NB‐OCOCH₃ content in the copolymers can be controlled up to 5.8–12.0% by varying the comonomer feed ratios from 10 to 50%. The copolymers exhibited high transparency, high glass transition temperature (T_g > 263.9 °C), better solubility, and mechanical properties compared with the homopolymer of NB. The reactivity ratios of the two monomers were determined to be r_NB‐OCOMe = 0.08, r_NB = 7.94 for Ni(II)/B(C₆F₅)₃ system, and r_NB‐OCOMe = 0.07, r_NB = 6.49, for Pd(II)/B(C₆F₅)₃ system by the Kelen‐Tüdõs method. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Pd(II) complexes bearing di‐ and monochelate fluorinated β‐ketonaphthyliminato ligand and their catalytic properties towards vinyl‐addition polymerization and copolymerization of norbornene and ester‐functionalized norbornene derivative

Fluorinated β‐ketonaphthyliminate ligand CF₃C(O)CHC[HN(naphthyl)]CH₃ ( L1 ) and Pd(II) complexes with dichelate fluorinated β‐ketonaphthyliminato ligand, {CF₃C(O)CHC[N(naphthyl)]CH₃}₂Pd ( C1 ), as well as with monochelate fluorinated β‐ketonaphthyliminato ligand, {CF₃C(O)CHC[N(naphthyl)]CH₃}Pd(CH₃)(PPh₃) ( C2 ), were synthesized and their solid‐state structures were confirmed using X‐ray crystallographic analysis. The Pd(II) complexes were employed as precursors to catalyze norbornene (NB) homo‐ and copolymerization with ester‐functionalized NB derivative using B(C₆F₅)₃ as a co‐catalyst. High activity up to 2.3 × 10⁵ g_polymer mol_Pd^?1 h^?1 for the C1 /B(C₆F₅)₃ system and 3.4 × 10⁶ g_polymer mol_Pd^?1 h^?1 for the C2 /B(C₆F₅)₃ system was exhibited in NB homopolymerization. Moreover, the Pd(II) complexes exhibited a high level of tolerance towards the ester‐functionalized MB monomer. In comparison with the C1 /B(C₆F₅)₃ system, the C2 /B(C₆F₅)₃ system exhibited better catalytic property towards the copolymerization of NB with 5‐norbornene‐2‐carboxylic acid methyl ester (NB‐COOCH₃), and soluble vinyl‐addition‐type copolymers were obtained with relatively high molecular weights (3.6 × 10⁴–7.5 × 10⁴ g mol^?1) as well as narrow molecular weight distributions (1.49–2.15) depending on the variation of monomer feed ratios. The NB‐COOCH₃ insertion ratio in all copolymers could be controlled in the range 2.8–21.0 mol% by tuning a content of 10–50 mol% NB‐COOCH₃ in the monomer feed ratios. Copolymerization kinetics were expressed by the NB and NB‐COOCH₃ monomer reactivity ratios: r_NB‐COOCH3 = 0.18, r_NB = 1.28 were determined for the C1 /B(C₆F₅)₃ system and r_NB‐COOCH3 = 0.19, r_NB = 3.57 for the C2 /B(C₆F₅)₃ system using the Kelen–Tüdõs method. Copyright © 2014 John Wiley & Sons, Ltd.     

Rhodium‐ and ruthenium‐complex‐catalyzed condensation of ferrocene‐containing dithiols and diols with diarylsilanes to give silaferrocenophanes and ferrocene polymers

1,1′‐Ferrocenedithiol reacts with di(4‐methoxyphenyl)silane, diphenylsilane, and di(4‐fluorophenyl)silane in the presence of RhCl(PPh₃)₃ catalyst to give mixtures of 2,2‐diaryl‐1,3‐dithia‐2‐sila[3]ferrocenophanes (1a–3a) and ? (Fc? S? SiAr₂? S) _n? (Fc = 1,1′‐ferrocenylene; 1b: Ar = C₆H₄OMe‐4; 2b: Ar = Ph; 3b: Ar = C₆H₄F‐4). The products are isolated and characterized by NMR spectroscopy and elemental analyses. The polymers 1b–3b, obtained from a toluene‐soluble fraction of the products, show GPC elution patterns corresponding to M_n values of 2700–4600 (polystyrene standards). The UV–vis spectra of the ferrocenophanes and polymers exhibit a d–d transition peak at about 440 nm, while the polymers show a π–π* transition peak at 320–330 nm. The cyclic voltammograms of 3a (Ar = C₆H₄F ? 4) and 3b show a reversible redox of the iron center at 0.27 V and 0.35 V (Ag⁺/Ag) respectively. Reaction of 1,1′‐ferrocenedimethanol with diphenylsilane in the presence of RuCl₂(PPh₃)₃ catalyst results in selective formation of 3,3‐diphenyl‐2,4‐dioxa‐3‐sila[5]ferrocenophane ( 4 ), whose structure was determined by X‐ray crystallography. Copyright © 2001 John Wiley & Sons, Ltd.     

Vinyl polymerization of norbornene by mono‐ and trinuclear nickel complexes with indanimine ligands

A series of new indanimine ligands [ArN?CC₂H₃(CH₃)C₆H₂(R)OH] (Ar = Ph, R = Me ( 1 ), R = H ( 2 ), and R = Cl ( 3 ); Ar = 2,6‐i‐Pr₂C₆H₃, R = Me ( 4 ), R = H ( 5 ), and R = Cl ( 6 )) were synthesized and characterized. Reaction of indanimines with Ni(OAc)₂·4H₂O results in the formation of the trinuclear hexa(indaniminato)tri (nickel(II)) complexes Ni₃[ArN = CC₂H₃(CH₃)C₆H₂(R)O]₆ (Ar = Ph, R = Me ( 7 ), R = H ( 8 ), and R = Cl ( 9 )) and the mononuclear bis(indaniminato)nickel (II) complexes Ni[ArN?CC₂H₃(CH₃)C₆H₂(R)O]₂ (Ar = 2,6‐i‐Pr₂C₆H₃, R = Me ( 10 ), R = H ( 11 ), and R = Cl ( 12 )). All nickel complexes were characterized by their IR, NMR spectra, and elemental analyses. In addition, X‐ray structure analyses were performed for complexes 7 , 10 , 11 , and 12 . After being activated with methylaluminoxane (MAO), these nickel(II) complexes can polymerize norbornene to produce addition‐type polynorbornene (PNB) with high molecular weight M_v (10⁶ g mol^?1), highly catalytic activities up to 2.18 × 10⁷ gPNB mol^?1 Ni h^?1. Catalytic activities and the molecular weight of PNB have been investigated for various reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 489–500, 2008     

Synthesis and structures of the 2-(dimethylsila)pyrimidine derivatives (Ar = Ph, C6H4Bu-4; X = H, SiMe3, Li(hmpa)2, K(thf)3; n = 1, 2)

Five crystalline 2-(dimethylsila)pyrimidine derivatives (Z) have been prepared in excellent 1–4 or satisfactory 5 yield and characterised. The source of each was ultimately Li[CH(SiMe₂R)(SiMe₂OMe)] [R = Me (B) or OMe (I)]. Compound 1 (Z with Ar = Ph, X = SiMe₃, n = 1) was obtained from Z [with Ar = Ph, X = Li(OEt₂), n = 4; previously isolated from B [P.B. Hitchcock, M.F. Lappert, X.-H. Wei, J. Organomet. Chem. 689 (2004) 1342]] and Me₃SiCl. The potassium salt 2 [Z with Ar = C₆H₄Bu^t-4; X = K(thf)₃, n = 2] was made from K[CH(SiMe₃)(SiMe₂OMe)] (C) (via B) and 4-Bu^tC₆H₄CN. Treatment of 2 with 1,2-dibromoethane afforded 3 (Z with Ar = 4-Bu^tC₆H₄; X = H, n = 1); which when reacted with successively n-butyllithium and Me₃SiCl produced 4 (Z with Ar = 4-Bu^tC₆H₄, X = SiMe₃, n = 1). Compound 5 [Z with Ar = 4-Bu^tC₆H₄, X = Li(hmpa)₂, n = 1] resulted from I with 4-Bu^tC₆H₄CN and then OP(NMe₂)₃ (≡ hmpa). Plausible reaction pathways from the appropriate alkali metal alkyl C or I to 2 or 5, respectively, are suggested; these involve regiospecific 1,3-migrations of SiMe₂OMe from C → N and electrocyclic loss of Me₃SiOMe or SiMe₂(OMe)₂, respectively. The X-ray structures of crystalline 1, 2 and 5 are presented.