(1)H-NMR study of ternary platinum(II) complexes with N-(1-Naphtyl)methyl-1,2-ethanediamine or N-(9-anthrylmethyl)-1,2-ethanediamine and bipyridine or phenanthroline and restricted single bond rotation due to aromatic-aromatic ring interaction.
(1)H-NMR spectra of square-planar complexes with the formula [Pt(L(1))(L(2))]X(2) where L(1) is 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) and L(2) is N-(1-naphthyl)methyl-1,2-ethanediamine (Npen) or N-(9-anthryl)methyl-1,2-ethanediamine (Aten) indicate that the N-naphthylmethyl and N-anthrylmethyl groups are forced to adopt a pseudo axial disposition due to intramolecular repulsion of hydrogen atoms of the aromatic diimines. The aromatic-aromatic interactions in the N-arylmethyl-1,2-ethanediamine complexes and aromatic diimines caused them to undergo intramolecular stacking. (1)H-NMR spectra of these complexes showed a significant concentration and temperature dependence. The monomer-dimer equilibrium was estimated, based on the concentration dependency. Restricted single bond rotation was estimated from temperature dependency data. The rotation of the anthracene ring of the [Pt(bpy)(Aten)](2+) complex showed an activation energy of ca. 38 kJ mol(-1), which is in good agreement with a mechanism involving successive rotations about single bonds with restriction by intramolecular aromatic-aromatic ring interactions.
Yamakawa
Naoki
N
Graduate School of Pharmaceutical Sciences, Kumamoto University, Japan. bananao@gpo.kumamoto-u.ac.jp
Sumimoto
Masamitsu
M
Matsumoto
Takashi
T
Yuto
Koji
K
Yoshikawa
Yuzo
Y
Goto
Masafumi
M
Yamaguchi
Yoshihiro
Y
Kurosaki
Hiromasa
H
D015082:2,2'-Dipyridyl / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009944:Organoplatinum Compounds / Q000737:chemistry*; D010618:Phenanthrolines / Q000737:chemistry*; D013816:Thermodynamics
D009944:Organoplatinum Compounds; D010618:Phenanthrolines; D015082:2,2'-Dipyridyl