333334-62-6

Upstream product

• 109-97-7 pyrrole 
• 1109-15-5 tris(pentafluorophenyl)borate 
• 7647-01-0 hydrogenchloride 
• 333334-61-5 [(C₄H₄N)B(C₆F₅)3]Li*(C₂H₅)2O 
• 20671-52-7 lithium pyrrolide 

Downstream Products

• 2138-72-9 N-[tris(pentafluorophenyl)borane]-pyridine 

Relevant academic research and scientific papers

Synthesis and reactivity of (C6F5)3B-N-heterocycle complexes. 1. Generation of highly acidic sp3 carbons in pyrroles and indoles

The reaction of pyrroles and indoles with B(C6F5)3 and BCl3 produces 1:1 B-N complexes containing highly acidic sp3 carbons, for example, N-[tris(pentafluorophenyl)borane]-5H-pyrrole (1) and N-[tris(pentafluorophenyl)borane]-3H-indole (2), that are formed by a new formal N-to-C hydrogen shift, the mechanism of which is discussed. With some derivatives, restricted rotation around the B-N bond and/or the B-C bonds was observed by NMR techniques, and some rotational barriers were calculated from experimental data. The acidity of the sp3 carbons in these complexes is shown by their ability to protonate NEt3, with formation of pyrrolyl- and indolyl-borate ammonium salts. The driving force for this reaction is given by the restoration of the aromaticity of the heterocycle.

Preparation of chelate bis(imine)nickel allyl systems by reaction of their corresponding butadiene complexes with electrophiles

The chelate 1,2-bis(imine)nickel(butadiene) complex 4a (chelate ligand derived from condensation of biacetyl with 2,6-diisopropylaniline) adds the strong Lewis acid B(C6F5)3 at the terminal carbon atom of the butadiene ligand to yield the dipolar substituted π-allyl-type betaine complex (lig)Ni[η 3-C3H4-CH2B(C6 F5)3] (Z-6a). At 90 °C the kinetically formed product equilibrated with its E-6a isomer. Similarly, 4a adds the boron Lewis acid (pyrrolyl)B(C6F5)2 to yield the corresponding neutral dipolar π-allyl betaine complex Z-7a, that slowly equilibrated with E-7a over several hours at ambient temperature. Protonation of the butadiene ligand of complex 4a was achieved by treatment with the neutral Br?nsted acid (2H-pyrrol) B(C6F5)3 to yield the [(lig)Ni (η3-crotyl)+][(pyrrolyl)B(C6 F5)3-] salt 9a (Z-/E-9a ratio=90:10 upon preparation). At 298 K this salt rearranged to a 5:95 mixture of Z-9a/E-9a with a Gibbs activation energy of Δ G ? (298 K)=22.3±0.2 kcal mol-1. Complex 4a added [Ph3C+] to the butadiene ligand to yield the salt [(lig)Ni(η3-C3H4-CH2 CPh3)+][B(C6F5)4 -] (Z-12a), that proved isomerically stable under the applied reaction conditions. Similar reactions were carried out starting from the acenaphthylene 1,2-dione derived chelate bis(imine)Ni(butadiene) complex 4b. The systems 6, 7, 9 and 12 were found to be active ethene polymerization catalysts in the presence of Al(i-Bu)3.

Protonation of the heterocyclic cp-anion equivalent [pyrrolyl-B(C6F5)3]Li - Formation of a useful neutral bronsted acid for the generation of homogeneous metallocene ziegler catalysts

N-pyrrolyllithium (1) adds to B(C6F5)3 to yield [(C4H4N)B(C6F5)3 ] Li (3). The corresponding monoetherate (3·OEt2) was characterized by X-ray diffraction and shows an η5 coordination of the pyrrolyl moiety to the lithium cation. Treatment of 3 with HC1 in ether leads to H+ addition at a pyrrolyl α-position to yield the neutral dipolar Bronsted acid system [(C4H5N)B(C6F5)3 ] (4). The reagent 4 can be used to protonate Cp2Zr(CH3)3 to yield [Cp2Zr(CH3)+(C4H4N)B- (C6F5)3-] (6) and methane. H+ transfer from 4 to (butadiene)-zirconocene results in the formation of the (π-allyl)metallocene salt [(C4H7)ZrCp2+(C4 H4 (C6F5)3-] (8). In analogous reactions, the neutral Bronsted acid was employed as a protonating activator component for the generation of homogeneous Ziegler catalysts derived from a variety of (butadiene)-or (dimethyl)ansa-metallocenes. The systems generated by treatment with 4 show comparable activities in ethene or propene polymerization reactions as conventionally generated Group 4 metallocene Ziegler catalysts.