Mauro Fianchini

Eco-friendly synthesis of high-quality polyaniline using a copper(II) scorpionate catalyst

High-quality polyaniline with conductivity reaching 5 S cm−1 has been prepared catalytically in acetonitrile using aniline, HCl, hydrogen peroxide, and 2 mol% of the copper catalyst methyl[tris(3-mesityl-1-pyrazolyl)borato]copper(II) chloride ([MeB(3-(Mes)Pz)3]CuCl). The use of CuCl2·2H2O catalyst instead of [MeB(3-(Mes)Pz)3]CuCl and the solvent effects were also investigated. Polyaniline samples were characterized using CHN analysis, UV-visible spectroscopy, FT-IR spectroscopy, bulk conductivity measurements, cyclic voltammetry and electrochemical impedance spectroscopy. Results of these mutually independent techniques are consistent and indicate the formation of good quality emeraldine form of polyaniline from the [MeB(3-(Mes)Pz)3]CuCl catalyzed reaction in acetonitrile. The conductivity of the polymer prepared using [MeB(3-(Mes)Pz)3]CuCl catalyst depends strongly on the medium of preparation which follows the order acetonitrile > 1 : 1 acetonitrile–water mixture > water. The polymer prepared using CuCl2·2H2O instead of [MeB(3-(Mes)Pz)3]CuCl in a 1 : 1 acetonitrile–water mixture is of relatively poor quality and has a lower conductivity. HCl is also important for the formation of better quality polyaniline and higher yield.

FLUORINATED TRIS(PYRAZOLYL)BORATES AND SILVER(I) COMPLEXES OF GROUP 14 LIGANDS

This review presents an overview of fluorinated tris(pyrazolyl)borate ligands and their role in the development of silver adducts containing group 14 ligands. Tris(pyrazolyl)borates bearing fluorocarbon substituents are sterically somewhat similar but electronically very different from their hydrocarbon counterparts. They have weakly donating nitrogen sites. Fluorinated hydridotris(pyrazolyl)borates also have less reducing B-H groups. These mono-anionic, nitrogen-based donors are ideal supporting ligands to stabilize silver complexes bearing labile donors. For example, fluorinated tris(pyrazolyl)borates have enabled the isolation of thermally stable Ag(I)-CO, Ag(I)-ethylene, and Ag(I)-acetylene adducts. Compounds with unsupported Ag(I)-Ge(II) and Ag(I)-Sn(II) bonds have also been synthesized. Most of these contain easily removable halide groups and silver atoms in the same molecule, but do not show the silver-halide metathesis. Fluorinated tris(pyrazolyl)borate ligands without the problematic B-H moiety have been reported. They afford silver-tris(pyrazolyl) borates with higher solution stability. The κ3-coordination mode is the most common for tris(pyrazolyl)borates but κ2-bonded tris(pyrazolyl)borate silver adducts are also known. Some silver adducts of fluorinated tris(pyrazolyl)borates are excellent tris(pyrazolyl)borato ligand transfer agents, promising homogeneous catalysts and effective antimicrobial agents.

A non-classical copper carbonyl on a tri-alkene hydrocarbon support

Two rare copper complexes, a tri-alkene adduct [Cu(ttt-cdt)(FSbF(5))] and a non-classical carbon monoxide complex [Cu(ttt-cdt)(CO)][SbF(6)] with a high CO stretching frequency ([small nu, Greek, macron](CO) = 2160 cm(-1)), have been isolated using trans,trans,trans-1,5,9-cyclododecatriene (ttt-cdt) ligand.