2.2.1. Diaminoand Aminohydrazinocarbenes 3338 2.2.2. Aminothioand Aminooxycarbenes 3340 2.3. Phosphinoaryland Phosphinoalkylcarbenes 3341 2.4. Aminoaryland Aminoalkylcarbenes 3344 2.5. Aminophosphonio and Aminosilylcarbenes 3346 2.6. Aminophosphinocarbenes 3347 3. Reactivity 3348 3.1. Typical Carbene Behavior 3348 3.1.1. Coupling Reactions 3348 3.1.2. Cycloaddition Reactions 3352 3.1.3. Insertion Reactions 3355 3.1.4. Migration Reactions 3358 3.2. Basic/Nucleophilic Behavior 3359 3.2.1. Protonation of Carbenes 3359 3.2.2. Reactions with Group 14 Electrophiles 3360 3.2.3. Reactions with Group 13 Lewis Acids 3360 3.2.4. Reactions with Group 15 Electrophiles 3361 3.3. Electrophilic Behavior 3362 3.3.1. Reaction with 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN) 3362

Stable Noncyclic Singlet Carbenes

λ3-Phosphinocarbenes λ5-phosphaacetylenes

Carbenes and Carbenoids in Synthesis of Heterocycles

Publisher Summary Carbenes are electron-deficient, two-coordinate carbon compounds that have two nonbonding electrons at one carbon. This chapter reviews the theoretical aspect, synthesis, structural features, reactivity, and ligand properties of phosphinocarbenes. The (phosphino) (silyl)- and (phosphino) (phosphonio) carbenes are the only stable carbenes that feature a π-donor and a π-type-withdrawing substituent. They have a singlet ground state with a planar environment at phosphorus and a short phosphorus–carbon bond distance. However, because of the reluctance of phosphorus to keep this planar geometry, these “push-pull” carbenes behave in a manner very close to that of the most of the transient carbenes. Their lack of reactivity toward transition-metal centers is probably due to the excessive steric hindrance about the carbene center. They are excellent ligands for metal centers, and some of the complexes prepared show promising catalytic activity. Multinuclear nuclear magnetic resonance (NMR) spectroscopy is the most informative technique for analyzing the structure and bonding of phosphinocarbenes. The reactivity of phosphinocarbenes is strongly dependent on the nature of the other carbene substituent. A few complexes featuring a phosphinocarbene ligand in a number of different coordination modes (A, B, and C) are described.

The Chemistry of Phosphinocarbenes

Bis(diisopropylamino)(trimethylstannyl)phosphane (2) reacts with the (chloromethylene)diisopropylammonium salt 1 affording the C-phosphanyl-substituted iminium salt 3 (67 % yield), which features a short C–N (1.284 A) and a long P–C bond (1.850 A), a planar iminium nitrogen atom and a pyramidalized phosphorus atom. Deprotonation of 3 leads to the enamine 8 (92 % yield), while addition of sodium methoxide followed by thermolysis of the resulting hemiaminal 9 (90 % yield) gives rise to the azaphosphetane 10 (85 % yield), by intramolecular CH insertion of the transiently formed (amino)(phosphanyl)carbene 6.

The inferior p-donor ability of phosphanyl versus amino substituents : consequences on the stability and reactivity of phosphanyl- and aminocarbenes

Heating of bis[bis(diisopropylamino)phosphanyl]diazomethane 7. in refluxing benzene for 48 hours, quantitatively led to the corresponding 1.2λ3-azaphosphetane 9 as only one diastereoisomer. This result is explained in terms of carbene insertion into a methin-CH bond of an isopropyl substituent. The regiospecificity and the stereospecificity of the ring closure is discussed. Treatment of 9 with elemental sulfur afforded the corresponding 1.2.2λ3-azathiophosphetane 10 which has been characterized b X ray crystallo raphy: C25H56N4P2S2, space group P2(l)/n, a = 13.628 (3) A, 6 = 19.369 (5) A, c 112.485 (4) A, V = 3073 (3) A3.

STEREOSPECIFIC FORMATION OF A 1,2λ3 -AZAPHOSPETANE IN THE THERMOLYSIS OF BIS[BIS(DIISOPROPYLAMINO)PHOSPHANYL] DIAZOMETHANE

The invention relates to an anticorrosion treatment process in which applied to an oxidizable surface of a solid metal substrate is a liquid solution, referred to as treatment solution, comprising: at least one alkoxysilane, and at least one cerium (Ce) cation; in a liquid aqueous-alcoholic composition, said treatment solution being suitable for being able to form, at the surface of the solid metal substrate, a hybrid matrix by hydrolysis/condensation of each alkoxysilane(s) and of each cerium (Ce) cation; the treatment solution having a molar ratio (Si/Ce) of silicon element of the alkoxysilane(s) with respect to the cerium (Ce) cation(s) of between 50 and 500; characterized in that the cerium (Ce) cation(s) has(have) a concentration between 0.005 mol/L and 0.015 mol/L in the treatment solution.

Process for the anticorrosion treatment of a solid metal substrate and treated solid metal substrate capable of being obtained by such a process

T goal of this study is to develop an innovative coating in accordance with the environmental regulations REACH and RoHS. Innovation will consist in an original approach of the sol-gel process implementation. Compared to the current plating’s, environmental unfriendly processes due to hazardous chemicals to health and environment, this innovative liquid process is very interesting to work on many different substrates. The formulation is designed according to the required properties of the coating, throughout an appropriate surface structuration. The originality of the approach is to develop a formulation with an adequate choice of precursors and fillers which bring simultaneously anticorrosion and electrical conductivity. The literature provides many solgel formulations, and the most suitable for complex shape parts are composed of both organic and inorganic precursors. They are named organic inorganic hybrid (OIH) sol-gel coating-1. Coating flexibility and anticorrosion properties are some of the properties provided by an OIH coating. In our study, organic and inorganic precursors are selected towards anticorrosion properties. Inhibitor is also added to sol-gel matrix-2 to improve the corrosion resistance. Some works have been performed on the influence of different fillers on the electrical properties of the polymer matrix-3, but the innovative study here is to combine the anticorrosion and electrical properties in a coating prepared by sol-gel route. To bring electrical properties to sol-gel coating, different fillers are taking on and studied. Influence of fillers natures, form factors and quantities are evaluated to find an optimum composition. Electrical, viscosity and hydrophobic characterization are accomplished to file fillers in function of their behavior in the sol-gel matrix. Structural and microstructural characterizations are performed by 3D optical microscopy and scanning electron microscopy. The chemical interaction between the sol-gel coating and the substrate is also deeply characterized and specially the durability of materials under corrosive conditions by coupling salt spray test, electrochemical impedance spectroscopy, nano scratch and nano indentation.

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STEREOSPECIFIC FORMATION OF A 1,2λ3 -AZAPHOSPETANE IN THE THERMOLYSIS OF BIS[BIS(DIISOPROPYLAMINO)PHOSPHANYL] DIAZOMETHANE

Process for the anticorrosion treatment of a solid metal substrate and treated solid metal substrate capable of being obtained by such a process

Development of functionalized coating by sol-gel process on aluminium alloy

Composition de talc