NONBRIDGED HALF-TITANOCENES CONTAINING ANIONIC ANCILLARY DONOR LIGANDS:PROMISING NEW CATALYSTS FOR PRECISE SYNTHESIS OF CYCLIC OLEFIN COPOLYMERS(COCs)

Precise,efficient copolymerizations of ethylene with cyclic olefins[norbornene(NBE),cyclopentene(CPE)]using nonbridged half-titanocenes of type,Cp TiCl_2(L)(Cp =cyclopentadienyl group,L=aryloxo,ketimide)-MAO catalyst systems have been summarized.CpTiCl_2(N=C Bu_2)exhibited both remarkable catalytic activity and efficient NBE incorporation for ethylene/NBE copolymerization:the NBE incorporation by Cp TiCl_2(X)(X=N=C Bu_2,O-2,6- Pr_2C_6H_3; Cp =Cp,C_5Me_5,indenyl)was related to the calculated coordination ene...

ADMET Polymerization: Greener Method for Synthesis of End-Functionalized Poly(Arylene Vinylene)s

Recent results for synthesis of conjugated polymers, poly(arylene vinylene)s exemplified as poly(fluorene vinylene)s and poly(phenylene vinylene)s, by acyclic diene metathesis (ADMET) polymerization have been introduced. The methods using molybdenum and ruthenium catalysts afforded defect-free, high molecular weight polymers with all trans olefinic double bonds, and significant reduction of by-products (halogen, sulfur etc.) in addition of decrease of structurally defects have been attained. The methods also demonstrated precise synthesis of end-functionalized polymers that showed unique optical properties combined with the end groups. Catalytic one-pot syntheses of end-functionalized poly(9,9-dialkylfluorene-2,7-vinylene)s have been attained by both ruthenium (by chain-transfer) and molybdenum catalysts and the method should provide more green route for synthesis of conjugated materials with better device performance.

A Greener Approach for Synthesis of Functionalized Polyolefins by Introducing Reactive Functionality into Ethylene Copolymers

Recent successful examples for synthesis of new polyolefins containing (polar) functionalities by adopting the approaches by controlled incorporation of reactive functionalities (and the subsequent introduction of polar functionalities under mild conditions) by coordination polymerization in the presence of transition metal complex catalysts have been described. Related methods (such as direct copolymerization of olefin with polar monomer using living radical or coordination insertion methods) have also been demonstrated for comparison. Our recent efforts for precise synthesis of polyolefins containing polar functionalities by efficient incorporation of reactive functionality by copolymerization of ethylene with nonconjugateddiene (1,7-octadiene, vinylcyclohexene etc.) or divinyl-biphenyl using nonbridged half-titanocene [ex. Cp’TiCl2(O-2,6-iPr2C6H3), Cp’ = C5Me5, tBuC5H4 etc.] catalysts have been introduced.

(Arylimido)vanadium(V)-Alkylidene Complexes as Catalysts for Ring-opening Metathesis Polymerization(ROMP) of Cyclic Olefins: Ligand Design for Exhibiting the High Activity

(Imido)vanadium(V)-alkylidene complexes of type V(CHSiMe3)(NR)(OR?)(PMe3)2 [R = Ad, C6H5, 2,6-Me2C6H3, 2,6-Cl2C6H3;R?= 2,6-Me2C6H3, 2,6-i Pr2C6H3, 2,6-F2C6H3, C6F5, C6Cl5] exhibited from moderate to remarkable catalytic activities for ringopening metathesis polymerization(ROMP) of norbornene(NBE). The catalytic activities were affected by the ligand substituents, and V(CHSiMe3)(N-2,6-Cl2C6H3)(OC6X5)(PMe3)2(X = F, Cl) demonstrated the exceptionally high catalytic activities for ROMP of NBE.The complexes polymerized cycloheptene(CHPE) and cis-cyclooctene(COE), and ROMP of COE by the OC6 Cl5 analogue proceeded in a living manner even at 80℃, and the activity increased with increasing the temperature up to 120 ℃. Highly active catalysts for ROMP of cyclic olefins(NBE, cyclopentene, and CHPE) can be generated in situ by premixing isolated V(CHSiMe3)(NC6F5)(O-2,6-iPr2C6H3)(PMe3)2 with 1.0 equiv. of C6F5OH or C6Cl5OH via immediate phenoxy exchange;the activity was affected by the kind of phenol added [TOF in the ROMPs of NBE: 4.62 × 10^4 min^–1(upon addition of C6F5OH) versus 37.3 min^–1(none)].