Single-site catalysis by bimetallic zinc calixarene inclusion complexes.

نویسندگان

  • Ella Bukhaltsev
  • Limor Frish
  • Yoram Cohen
  • Arkadi Vigalok
چکیده

[reaction: see text] Bimetallic alkylzinc calixarene inclusion complexes were prepared and used in the ring-opening polymerization of L-lactide. Polymers with high molecular weight and a low degree of polydispersity were obtained. 1H NMR and diffusion NMR experiments suggest that a single-site mechanism is operative.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Grafted metallocalixarenes as single-site surface organometallic catalysts.

Metallocalixarenes were grafted onto silica using a surface organometallic approach and shown to be active and selective catalysts for epoxidation of alkenes using organic hydroperoxides. Calixarene-Ti(IV) precursors were anchored at surface densities from 0.1 to near-monolayer coverages (0.025-0.25 calixarene nm(-2)). Several spectroscopic methods independently detected calixarene-Ti(IV) conne...

متن کامل

Bimetallic redox synergy in oxidative palladium catalysis.

Polynuclear transition metal complexes, which are embedded in the active sites of many metalloenzymes, are responsible for effecting a diverse array of oxidation reactions in nature. The range of chemical transformations remains unparalleled in the laboratory. With few noteworthy exceptions, chemists have primarily focused on mononuclear transition metal complexes in developing homogeneous cata...

متن کامل

Bimetallic palladium catalysis: direct observation of Pd(III)-Pd(III) intermediates.

PhI(OAc)(2) is a common oxidant for Pd-catalyzed C-H bond functionalizations. Mechanistic hypotheses since the 1960s have suggested a Pd(II)/Pd(IV) mechanism. Here we present evidence for the relevance of bimetallic Pd(III) complexes to catalysis. A bimetallic Pd(III) acetate was isolated and can afford product by bimetallic reductive elimination.

متن کامل

The role of outer-sphere surface acidity in alkene epoxidation catalyzed by calixarene-Ti(IV) complexes.

Cooperativity between Brønsted acidic defect sites on oxide surfaces and Lewis acid catalyst sites consisting of grafted calixarene-Ti(IV) complexes is investigated for controlling epoxidation catalysis. Materials are synthesized that, regardless of the surface or calixarene substituent, demonstrate nearly identical UV-visible ligand-to-metal charge-transfer bands and Ti K-edge X-ray absorption...

متن کامل

Bimetallic Effect of Single Nanocatalysts Visualized by Super-Resolution Catalysis Imaging

Compared with their monometallic counterparts, bimetallic nanoparticles often show enhanced catalytic activity associated with the bimetallic interface. Direct quantitation of catalytic activity at the bimetallic interface is important for understanding the enhancement mechanism, but challenging experimentally. Here using single-molecule super-resolution catalysis imaging in correlation with el...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:
  • Organic letters

دوره 7 23  شماره 

صفحات  -

تاریخ انتشار 2005