Competition between C-C and C-H insertion in prototype transition metal-hydrocarbon reactions.
نویسندگان
چکیده
The competition between C-C and C-H insertion in model transition-metal reactions with cyclopropane and propene (C3H6) was studied as a function of total energy. Insertion of neutral transition metal atoms M (= Y, Zr, Nb, and Mo*) into the C-C bonds of cyclopropane led to formation of MCH2 + C2H4, whereas C-H insertion produced MC3H4 + H2. The measured product branching ratios verify the relative potential energy barrier heights for C-C and C-H insertion predicted by ab initio calculations.
منابع مشابه
Ab initio Study of Simple Mg-Ene Reactions of Propenyl Magnesium Halides and Ethylene (Type-I Intermolecular Reaction)
The insertion of an olefinic C=C bond into a metal-carbon bond is of potential interest as a preparativeroute to new products and as results of C-C coupling reactions to organic compounds. The allyl compoundsof Mg, react with an olefin by inversion of the allyl group via a six center transition state. These precyclicreactions may be one of the most important classes of organic reactions. The re...
متن کاملSelected applications to organic synthesis of intramolecular C-H activation reactions by transition metals
Cyclometallated compounds obtained via the well-known intramolecular C-H activation by transition metals of Nor Scontaining ligands may lead to organic heterocycles through reaction with alkynes. The mechanistic implications of the formation of both C-C and C-Y bonds are discussed. A reaction pathway involving insertion of the alkyne into the metalcarbon bond of the starting material followed b...
متن کاملPotentiometric Study of Complex Formation Between Some Transition Metal Ions and 2 - Aminopyridine. Part 1. A Model for Therapeutic Agent for Wilson’s Disease
The complexation reactions of some transition metal ions and 2-aminopyridine (2-ampy) were studied potentiometrically in aqueous solution at µ=0.1 M and 25 °C. The overall stability constants log β’s of all species are obtained by computer refinement of pH-volume data with using the BEST computer program. Several models were tested and the best one accepted according to the least sum of squ...
متن کاملAdvances in the development of catalytic tethering directing groups for C-H functionalization reactions.
Transition metal-catalyzed C-H bond insertion is one of the most straightforward strategies to introduce functionalities within a hydrocarbon microenvironment. For the past two decades, selective activation and functionalization of certain inert C-H bonds have been made possible with the help of directing groups (DGs). Despite the enormous advances in the field, an overwhelming majority of syst...
متن کاملEffect of Additives on Mn/SiO2 Based Catalysts on Oxidative Coupling of Methane
The Oxidative Coupling of Methane (OCM) over M-Na-Mn/SiO2 catalysts (M=W, Cr, Nb and V) was investigated using a continuous-flow quartz reactor at 775°C, 1 atm and 100 cm3min-1 gas flow rates, and correlated with the observed structure and redox properties.The interaction effects of the metal-metal and metal-support on the...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of the American Chemical Society
دوره 125 4 شماره
صفحات -
تاریخ انتشار 2003