40244-38-0Relevant academic research and scientific papers
Square-planar mesitylenido(triphenylphosphane)nickel(II) complexes containing bidendate N,O-ligands: Changes in catalytic efficiency upon small alterations in the ligand backbone
Beckmann, Udo,Lindner, Monika M.,Eichberger, Eva,Frank, Walter
, p. 73 - 80,8 (2020/08/24)
Square planar arenido(triphenylphosphane)nickel(II) complexes containing a heterocyclic bidentate N,O-chelate ligand are catalysts for the copolymerisation of ethene and carbon monoxide. To examine the influence of the N,O-ligand on the catalytic activity new nickel(II) complexes with altered heterocyclic ring size in the corresponding N,O-ligands were synthesised and fully characterised. The crystal structures of all protonated N,O-ligands and the corresponding nickel complexes were determined. The catalytic activity of the new complexes in the copolymerisation reaction of ethene and carbon monoxide as well as in the polymerisation reaction of ethene were studied.
Conjugative interaction in styrenes
Von Doering,Benkhoff, Johannes,Carleton, Peter Smart,Pagnotta, Marco
, p. 10947 - 10955 (2007/10/03)
Conjugative interactions of the carbon-carbon double bond are fundamental in organic chemistry. In this work, equilibria are established among conjugated and unconjugated isomers of two β-substituted styrenes, 1-phenylbut-1-ene and 1-phenyl-3-methylbut-1-ene, and one α,β-disubstituted styrene, 2-phenyl-5-methylhex-2-ene, over a range of temperatures (the van't Hoff method) in hexamethylphosphoric triamide and potassium tert-butoxide. From the trans styrenes of the first two sets, an enthalpy of conjugative interaction of phenyl vis-a-vis alkyl (ΔΔH(ConjInter/Alk)) = -2.5 ± 0.2 kcal/mol [-5.1 kcal/mol defined as phenyl vis-a-vis hydrogen (ΔΔH(ConjInter/H))] is observed, while the cis styrenes reveal an attenuated ΔΔH(ConjInter/Alk) of -1.1 kcal/mol (ΔΔH(ConjInter/H)) = -2.7 kcal/ mol). The α-methyl group in the third set also leads to a reduced conjugative interaction. Entropy plays an important role in determining positions of equilibrium. Free energies of conjugation are reported for several sterically hindered o-methyl-substituted styrenes.
