(Arylimido)vanadium(V)–Alkylidene Complexes Containing Fluorinated Aryloxo and Alkoxo Ligands for Fast Living Ring-Opening Metathesis Polymerization (ROMP) and Highly <i>Cis</i>-Specific ROMP

(Arylimido)­vanadium­(V)–alkylidene complexes, V­(CHSiMe₃)­(<i>N</i>-2,6-X₂C₆H₃)­(OC₆F₅)­(PMe₃)₂ [X = Me (<b>2</b>), Cl (<b>4</b>)], exhibited remarkable catalytic activities for ring-opening metathesis polymerization (ROMP) of norbornene, and the ROMP by <b>2</b> proceeded in a living manner, affording ultrahigh molecular weight polymers. <i>Cis</i>-specific ROMP was achieved with the alkoxo analogues, V­(CHSiMe₃)­(<i>N</i>-2,6-X₂C₆H₃)­[OC­(CH₃)­(CF₃)₂]-(PMe₃)₂ [X = Me (<b>5</b>), Cl (<b>6</b>)]. Both the activity and the selectivity increased upon addition of PMe₃, even at 50 °C

Catalytic One-Pot Synthesis of End-Functionalized Poly(9,9′-di‑<i>n</i>‑octylfluorenevinylene)s by Acyclic Diene Metathesis (ADMET) Polymerization Using Ruthenium–Carbene Catalysts

Synthesis of end-functionalized poly­(9,9′-di-<i>n</i>-octyl­fluorene­vinylene)­s (EF-PFVs) has been achieved by (i) catalytic olefin metathesis of vinyl groups (chain ends) in once prepared PFVs by acyclic diene metathesis (ADMET) polymerization with 1,2-disubstituted (bifunctional) olefins (DOs) or (ii) one-pot synthesis by combined ADMET polymerization (of 2,7-divinyl-9,9-di-<i>n</i>-octhyl­fluorene, DVF) with end-functionalization/chain transfer using DOs in the presence of ruthenium catalyst, RuCl₂(PCy₃)­(IMesH₂)­(CHPh) [<b>Ru</b>(<b>1</b>), Cy = cyclohexyl, IMesH₂ = 1,3-bis­(2,4,6-trimethyl­phenyl)­imidazolin-2-ylidene]. Efficient one-pot synthesis of a series of high molecular weight EF-PFVs has been achieved when DOs were added after a certain period of the ADMET polymerization

(Arylimido)Vanadium(V)-Alkylidenes Containing Chlorinated Phenoxy Ligands: Thermally Robust, Highly Active Catalyst in Ring-Opening Metathesis Polymerization of Cyclic Olefins

A series of (imido)­vanadium­(V)-alkylidene complexes containing pentachlorophenoxy ligand of type, V­(CHSiMe₃)­(N-2,6-R₂C₆H₃)­(OC₆Cl₅)­(PMe₃)₂ [R = H, Cl, F, CH₃], have been prepared, and the structure of V­(CHSiMe₃)­(N-2,6-Me₂C₆H₃)­(OC₆Cl₅)­(PMe₃)₂ was determined by X-ray crystallographic analysis. Ring-opening metathesis polymerization (ROMP) of cyclic olefins such as norbornene (NBE), cyclopentene (CPE), cycloheptene (CHPE), and <i>cis</i>-cyclooctene (COE) using these alkylidene catalysts have been explored, and V­(CHSiMe₃)­(<i>N</i>-2,6-Cl₂C₆H₃)­(OC₆Cl₅)­(PMe₃)₂ showed higher activities in the ROMP of CPE, CHPE, and COE than those of the reported V­(CHSiMe₃)­(N-2,6-Cl₂C₆H₃)­(OC₆F₅)­(PMe₃)₂. The activity in the ROMP of COE increased at high temperature until 120 °C, and the ROMPs of CHPE and COE proceeded without chain-transfer or termination (nor catalyst decomposition); the (quasi) living nature thus maintained even at 80 °C. The activities in the ROMPs of CHPE and COE (at 25 °C) increased upon addition of 1.0 equiv of B­(C₆F₅)₃, whereas the activity in the ROMP of NBE became negligible upon the addition. The order in the activity in the ROMP of cyclic olefins displayed as COE ≪ CHPE < CPE ≪ NBE, which is different from not only that in the ring strain energy but also that reported in the ROMPs using ruthenium–carbene catalysts

Copolymerizations of Norbornene and Tetracyclododecene with α‑Olefins by Half-Titanocene Catalysts: Efficient Synthesis of Highly Transparent, Thermal Resistance Polymers

Highly efficient synthesis of cyclic olefin (CO) copolymers with high glass transition temperatures (<i>T</i>_g) as well as high catalytic activity have been attained not only by copolymerization of norbornene (NBE) with α-olefins (1-hexene, 1-octene, 1-dodecene), but also by copolymerization of tetracyclododecene (TCD) with α-olefins using half-titanocene catalysts, Cp′TiCl₂(NC^<i>t</i>Bu₂) [Cp′ = ^<i>t</i>BuC₅H₄ (<b>1</b>), Cp (<b>2</b>)] in the presence of MAO. Linear relationships between the <i>T</i>_g values and the NBE or TCD contents were observed in all cases; <i>T</i>_g values in poly­(TCD-<i>co</i>-α-olefin)­s were higher than those in poly­(NBE-<i>co</i>-α-olefin)­s with the same CO contents. NBE and TCD incorporations in these copolymerization under high NBE or TCD feed conditions (especially by <b>2</b>) were not affected by α-olefin (number of methylene units in the side chain) employed. An introduction of terminal olefinic double bond into the polymer side chain could be attained, if the copolymerization of NBE with 1-octene by <b>1</b> was conducted in the presence of 1,7-octadiene

Synthesis of (Adamantylmido)vanadium(V)-Alkyl, Alkylidene Complex Trapped with PMe₃: Reactions of the Alkylidene Complexes with Phenols

V­(CHSiMe₃)­(NAd)­(CH₂SiMe₃)­(PMe₃)₂ (<b>1</b>, Ad = 1-adamantyl) has been isolated from V­(NAd)­(CH₂SiMe₃)₃ in the presence of PMe₃ (excess, 12 equiv) upon heating, and the reaction of <b>1</b> with 2,6-Me₂C₆H₃OH in <i>n</i>-hexane afforded V­(CHSiMe₃)­(NAd)­(O-2,6-Me₂C₆H₃)­(PMe₃)₂ (<b>2a</b>); structures of <b>1</b> and <b>2a</b> have been determined by X-ray crystallography. Reaction of <b>1</b> with C₆F₅OH in C₆D₆ afforded a mixture of V­(CHSiMe₃)­(NAd)­(OC₆F₅)­(PMe₃)₂ (<b>2b</b>) and V­(NAd)­(CH₂SiMe₃)₂­(OC₆F₅) (<b>3b</b>) and the PMe₃ adduct (<b>3b</b>-<b>PMe</b>_<b>3</b>), and the consumption rate of <b>1</b> decreased upon addition of PMe₃ or use of C₆F₅OD in place of C₆F₅OH, clearly suggesting that the reaction proceeds via coordination of C₆F₅OH and subsequent reaction with the alkylidene or the alkyl moiety. The catalytic activity in the ring-opening metathesis polymerization (ROMP) of norbornene by <b>1</b> increased upon addition of phenol; <b>1</b>-C₆F₅OH catalyst showed a remarkable activity (TOF 20 000 h^–1), affording high molecular weight polymer with a unimodal molecular weight distribution. Reactions with <b>2a</b>,<b>b</b> with phenol afforded the bis­(phenoxy) complexes, and it has been suggested that these reactions proceed via coordination of phenol and subsequent reaction with the alkylidene accompanying phenoxy exchange on the vanadium

Synthesis of Oligo(thiophene)-Coated Star-Shaped ROMP Polymers: Unique Emission Properties by the Precise Integration of Functionality

A facile synthesis of oligo­(thiophene)-modified (coated) “soluble” star (ball)-shaped polymers has been achieved via sequential living ring-opening metathesis polymerization (ROMP) of norbornene and a cross-linking reagent using Mo­(CHCMe₂Ph)­(N-2,6-^<i>i</i>Pr₂C₆H₃)­(O^<i>t</i>Bu)₂ as the initiator and oligo­(thiophene) carboxaldehydes for termination. The resultant star-shaped ROMP polymers containing ter- and tetrathiophene moieties exhibit unique emission properties due to an integration of the ROMP polymers (arranged functionalities): the blue emission was tuned to the white emission upon addition of 2-[2-[(<i>E</i>)-4-(dimethylamino)­styryl]-6-methyl-4<i>H</i>-pyran-4-ylidene]­malononitrile

Precise Synthesis of End-Functionalized Oligo(2,5-dialkoxy-1,4-phenylene vinylene)s with Controlled Repeat Units via Combined Olefin Metathesis and Wittig-Type Coupling

The precise synthesis of chemically, analytically pure oligo(2,5-dialkoxy-1,4-phenylene vinylene)s [OPVs, alkoxy = O(CH₂)₂OSi^<i>i</i>Pr₃] with strictly controlled repeat units (up to 15 repeat units) and well-defined end groups has been achieved by a combined olefin metathesis reaction of 2,5-dialkoxy-1,4-divinylbenzene or their derivatives with a molybdenum–alkylidene complex and the subsequent Wittig-type cleavage with their dicarboxaldehyde analogues. The effects of the repeat units and the end functional groups toward their UV–vis and the fluorescence spectra have been clearly demonstrated

Synthesis and Structural Analysis of Palladium(II) Complexes Containing Neutral or Anionic <i>C</i>₂‑Symmetric Bis(oxazoline) Ligands: Effects of Substituents in the 5‑Position

A series of neutral and cationic palladium­(II) complexes containing <i>C</i>₂-symmetric bis­(oxazoline) (BOX) ligands, (BOX)­PdCl₂ (<b>2a</b>–<b>d</b>), (BOX)­Pd­(Me)Cl (<b>3a</b>–<b>d</b>), and [(BOX)­PdMe­(2,6-Me₂C₅H₃N)]⁺PF₆^– (<b>4a</b>–<b>d</b>) [BOX: 2,2′-(2-propylidene)­bis­{(4<i>R</i>)-4-phenyl-5,5-dimethyl-2-oxazoline}, 2,2′-methylenebis­{(4<i>R</i>)-4-phenyl-5,5-dimethyl-2-oxazoline}, 2,2′-methylenebis­{(4<i>R</i>)-4,5,5-triphenyl-2-oxazoline}, and 2,2′-methylenebis­{(4<i>R</i>,5<i>S</i>)-4,5-diphenyl-2-oxazoline}], were prepared, and their structures were determined by X-ray crystallography. It was found that substituents at the 5-position (Ph, Me) in addition to substituents on the bridgehead carbon directly affect the structure around palladium, especially the BOX bite angle and the dihedral angles between the phenyl rings at the 4-position and the N₂Pd plane. Treatment of the bridged methylene proton in the BOX ligand (<b>1b</b>–<b>d</b>) with KH afforded the anionic BOX ligand; also, the neutral Pd complexes, (BOX)­PdMe­(2,6-Me₂C₅H₃N) (<b>5b</b>–<b>d</b>), could thus be prepared by reaction with Pd­(Me)­Cl­(cod) (cod = 1,5-cyclooctadiene); <b>5b</b>–<b>d</b> showed strong coordination to Pd, as demonstrated by X-ray crystallographic analysis

Precise Synthesis of Amphiphilic Multiblock Copolymers by Combination of Acyclic Diene Metathesis (ADMET) Polymerization with Atom Transfer Radical Polymerization (ATRP) and Click Chemistry

Various block (graft) copolymers have been prepared by combination of acyclic diene metathesis (ADMET) polymerization of 9,9-dialkyl-2,7-divinyl-fluorene with Cu-catalyzed atom transfer radical polymerization (ATRP) of styrene using macroinitiators prepared by introduction of initiating functionalities into poly­(9,9-dialkylfluorene-2,7-vinylene)­s (PFVs) chain ends: a precise synthesis of the amphiphilic ABCBA-type block copolymers has also been attained by subsequent combination with click reaction after modification of the chain end with NaN₃

Precise Synthesis of Poly(fluorene vinylene)s Capped with Chromophores: Efficient Fluorescent Polymers Modified by Conjugation Length and End-Groups

Poly­(9,9-di-<i>n</i>-octylfluorene-2,7-vinylene)­s containing F-BODIPY [PFV-(F-BODIPY)₂] and Zn­(II)-porphyrin have been prepared by olefin metathesis of the vinyl group in the PFV chain ends followed by subsequent Wittig-type coupling. An introduction of tris­(2,5-dialkoxy-1,4-phenylene vinylene) into PFV-(F-BODIPY)₂ has also been achieved. The emission properties can be modified by the PFV chain length, chromophore, and the middle segment: PFV-(F-BODIPY)₂ exhibits white-light emission with high quantum efficiency