7342-47-4Relevant articles and documents
Kinetic studies of the oxidative addition and transmetallation steps involved in the cross-coupling of alkynyl stannanes with aryl iodides catalysed by η2-(dimethyl fumarate)(iminophosphane)palladium(0) complexes
Crociani, Bruno,Antonaroli, Simonetta,Canovese, Luciano,Uguagliati, Paolo,Visentin, Fabiano
, p. 732 - 742 (2007/10/03)
The complexes [Pd(η2-dmfu)(P-N)] {dmfu = dimethyl fumarate; P-N = 2-(PPh2)C6H4-1-CH=NR, R = C 6H4OMe-4 (1a), CHMe2 (2a), C6H 3Me2-2,6 (3a), C6H3(CHMe 2)2-2,6 (4a)} undergo dynamic processes in solution which consist of a P-N ligand site exchange through initial rupture of the Pd-N bond at lower energy and an olefin dissociation-association at higher energy. According to equilibrium constant values for olefin replacement, the complex [Pd(η2-fn)(P-N)] (fn = fumaronitrile, 1b) has a greater thermodynamic stability than its dmfu analogue 1a. The kinetics of the oxidative addition of ArI (Ar = C6H4CF3-4) to 1a and 2a lead to the products [PdI(Ar)(P-N)] (1c, 2c) and obey the rate law, k obs = k1A k2A[ArI]. The k1A step involves oxidative addition to a reactive species [Pd(solvent)(P-N)] formed from dmfu dissociation. The k2A step is better interpreted in terms of oxidative addition to a species [Pd(η2-dmfu)(solvent) (κ1-P-N)] formed in a pre-equilibrium step from Pd-N bond breaking. The complexes 1c and 2c react with PhC≡CSnBu3 in the presence of an activated olefin (ol = dmfu, fn) to yield the palladium(0) derivatives [Pd(η2-ol)(P-N)] along with ISnBu3 and PhC≡CAr. The kinetics of the transmetallation step, which is rate-determining for the overall reaction, obey the rate law: kobs = k2T[PhC≡CSnBu3]. The k2T values are markedly enhanced in more polar solvents such as CH3CN and DMF. The solvent effect and the activation parameters suggest an associative S E2 mechanism with substantial charge separation in the transition state. The kinetic data of the above reactions in various solvents indicate that, for the cross-coupling of PhC≡CSnBu3 with ArI catalysed by 1a or 2a, the rate-determining step is represented by the oxidative addition and that CH3CN is the solvent in which the highest rates are observed. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
Mechanistic study on the cross-coupling of alkynyl stannanes with aryl iodides catalyzed by η2-(dimethyl fumarate)palladium(0) complexes with iminophosphine ligands
Crociani, Bruno,Antonaroli, Simonetta,Beghetto, Valentina,Matteoli, Ugo,Scrivanti, Alberto
, p. 2194 - 2202 (2007/10/03)
The reactions of [Pd(η2-dmfu)(P-N)] [dmfu = dimethyl fumarate; P-N = 2-(PPh2)C6H4-1-CH=NR, R = C6H4OMe-4 (1a), CHMe2 (2a)] and [Pd(η2-dmfu)(P-N)2] with IC6H 4CF3-4, ISnBu3 and PhC≡SnBu3 have been studied under pseudo-first-order conditions. The oxidative addition of IC6H4CF3-4 yields [PdI(C6H 4CF3-4)(P-N)] (1b or 2b). No reaction takes place with PhC≡CSnBu3 and also with ISnBu3 in the presence of an excess of PhC≡CSnBu3. In the presence of fumaronitrile (fn), 1b and 2b undergo transmetalation by PhC≡CSnBu3 followed by fast reductive elimination to yield [Pd(η2-fn)(P-N)]. The same reaction sequence occurs for the system [PdI(C6H4CF 3-4)(P-N)]/P-N (1: 1 molar ratio) to give [Pd(η2-fn) (P-N)2]. The palladium(0) complexes are active catalysts in the cross-coupling of PhC≡CSnBu3 with aryl iodides ArI (Ar = C 6H4CF3-4, Ph). The catalytic efficiency depends on the complex: [Pd(η2-dmfu)(P-N)2] > [Pd(η2-dmfu)(P-N)], and on the substituent R: C6H 4OMe-4 > CHMe2. The reactivity and spectroscopic data suggest a catalytic cycle involving initial oxidative addition of ArI to a palladium(0) species, followed by transmetalation of the product and by fast reductive elimination to regenerate the starting palladium(0) compound. For [Pd(η2-dmfu)(P-N)] as catalyst, the oxidative addition is the rate-determining step, while for [Pd(η2-dmfu)(P-N)2] the oxidative addition and the transmetalation steps occur at comparable rate. The Royal Society of Chemistry 2003.
Improvement of the extended one-pot (EOP) procedure to form poly(aryleneethynylene)s and investigation of their electrical and optical properties
Pizzoferrato,Berliocchi,Di Carlo,Lugli,Venanzi,Micozzi,Ricci,Lo Sterzo
, p. 2215 - 2223 (2007/10/03)
A series of π-conjugated homopolymers of type poly(aryleneethynylene) (PAE), [-Ar-C≡C-]n, (Ar = 2,5-bis(butoxy)benzene (7a), 2,5-bis(octyloxy)benzene (7b), 2,5-bis(hexadecyloxy)benzene (7c), 3-butylthiophene (7d), and 3-hexadecylthiophene (7e)) have been prepared by further improvement of the palladium-catalyzed Extended One-Pot (EOP) synthetic protocol. With the use of dioxane as solvent and higher reaction temperature (110°C), much higher polymerization degree, improved catalytic efficiency, and increased material purity were obtained. Numerical simulations have been performed in a series of different conjugated polymers in order to evaluate the role of the connection between aromatic rings in the maintaining of an effective electronic conjugation through the polymer chain. Experimentally, the conjugation properties have been investigated by means of photophysical measurements in liquid solution and in solid-state films. The electric transport properties have been characterized in view of applications to electronic devices.