Hp. Wu et al., 5,5-dicyano-2,2 '-bipyridine silver complexes: discrete units or co-ordination polymers through a chelating and/or bridging metal-ligand interaction, J CHEM S DA, (2), 1999, pp. 183-190
Citations number
56
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
The ambidentate ligand 5,5'-dicyano-2,2'-bipyridine (L) was found to functi
on as a bi-, tri- or tetra-dentate chelate or chelate/bridging ligand in th
e co-ordination of silver ions. The mode of co-ordination depends on the an
ion and the crystallization conditions and was elucidated by single crystal
X-ray diffractometry. With metal-co-ordinating anions such as NO3- and CF3
SO3- a tridentate co-ordination mode of L is observed which involves the tw
o bipyridine nitrogen donor atoms and one cyano group. The latter bridges t
o a neighboring silver center so that a one-dimensional co-ordination polym
er results. For NO3- this co-ordination polymer forms a 2(1) helix. With le
ss co-ordinating anions such as BF4- and PF6- monomeric bis-chelate complex
es are obtained, where L assumes a bidentate co-ordinating mode involving o
nly the bipyridine nitrogen donor atoms. In the case of the PF6- anion a va
riation in the solvent of crystallization also produced a two-dimensional h
exagonal co-ordination polymer where L functions as a tetradentate ligand u
sing all four nitrogen donor atoms in chelation and bridging to the silver
centers.