Alkyl halide charge transfer complexes with hard Lewis bases.
The unusual charge transfer complexes formed between alkyl halide acceptors and hard Lewis base donors (amines and alcohols) in low dielectric solvent were examined using ultraviolet spectroscopy. The lambda(max) of the complex decreases with increasing ionization potential of the donor. The complex formation equilibria were probed by thermodynamic analysis and concentration variation. At ambient temperatures complex formation is generally slightly exergonic with a negative complexation entropy. The complex extinction coefficients are much lower (<10 l mol(-1) cm(-1)) than for typical charge transfer complexes. These complexes are extraordinary within a classical context since the halide acceptors have a negative electron affinity. They exhibited an atypical hypsochromic shift with increasing solvent dielectric constant.
Miller
John B
JB
Chemistry Department, Western Michigan University, Kalamazoo, MI 49008, USA. john.b.miller@wmich.edu
Kondilenko
Volodymyr P
VP
Salvador
James R
JR
Pontes
Raquel
R
D002621:Chemistry / Q000379:methods; D006219:Halogens / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D008956:Models, Chemical; D010777:Photochemistry; D013053:Spectrophotometry; D013816:Thermodynamics; D014466:Ultraviolet Rays
D006219:Halogens