Syntheses and characterizations of the Unsymmetrical Ligand (H2nypmpda) and Its Hexanuclear Nickel Complexes
Date Issued
2007
Date
2007
Author(s)
Huang, Yu-kai
DOI
zh-TW
Abstract
Abstact
The aim of this study is to investigate the synthesis, structures, and correlative
properties of linear hexanickel metal string complexes, where the ligand is N-
(1,8-naphthyridin-7-yl)-N’-(pyrimidin-2-yl)pyridine-2,6-diamine (H2nypmpda).
One novel unsymmetrical ligand (H2nypmpda) was synthesized by
palladium-catalyzed cross-coupling of N-(6-bromopyridin-2-yl)-1,8-naphthyridin-2-
amine (L2) with 2-aminopyrimidine.
[Ni6(μ6-nypmpda)4Cl2](ClO4)2 (1) were synthesized by reaction of ligand
H2nypmpda and nickel ion in melt naphthalene under basic condition. The
one-electron reduced hexametal string complex [Ni6(μ 6-nypmpda)4Cl2]PF6 (2) was
generated by reacting the hexanickel complex with the reductant N2H4. The
structures of compounds 1 and 2 were characterized by single-crystal X-ray
diffraction analysis. The X-ray structural studies reveal that the terminal nickel ions
are five-coordinated and the inner nickel ions are four-coordinated. The difference
in the structures 1 and 2 are the distances of Ni(1)-Ni(2) and Ni(2)-N, the Ni(1)-Ni(2)
distance is shorter in 2 and Ni(2)-N distances are longer in 2. This attributes to the
adding electron to dx2-y2 which is bonding to Ni(1)-Ni(2) and antibonding to Ni(2)-N
bonds.
The results of magnetic study show that complex 1 has a weak antiferromagnetic
interaction between two terminal Ni(II) atoms and the coupling constant is -2.89 cm-1.
Cyclic voltammetrical data show that complex 1 exhibits four couples ( E(red1)
1/2
= -0.07、E(red2)
1/2 = -0.24、E(red3)
1/2 = -0.46、E(red4)
1/2 = -0.68 ) and complex 2 has two
couples ( E(red1)
1/2 = -0.08、E(red2)
1/2 = -0.63 ). These data indicate that complex 1 can be
reduced easily.
Subjects
金屬串
吡
啶
metal string
pyridine
Type
thesis