Mixed valence aspects of diruthenium complexes [{(L)ClRu}(2)(mu-tppz)](n+) incorporating 2-(2-pyridyl)azoles (L) as ancillary functions and 2,3,5,6-tetrakis(2-pyridyl)pyrazine (Tppz) as bis-tridentate bridging ligand

DSpace/Manakin Repository

Mixed valence aspects of diruthenium complexes [{(L)ClRu}(2)(mu-tppz)](n+) incorporating 2-(2-pyridyl)azoles (L) as ancillary functions and 2,3,5,6-tetrakis(2-pyridyl)pyrazine (Tppz) as bis-tridentate bridging ligand

Show full item record

Title: Mixed valence aspects of diruthenium complexes [{(L)ClRu}(2)(mu-tppz)](n+) incorporating 2-(2-pyridyl)azoles (L) as ancillary functions and 2,3,5,6-tetrakis(2-pyridyl)pyrazine (Tppz) as bis-tridentate bridging ligand
Author: CHANDA, N; SARKAR, B; KAR, S; FIEDLER, J; KAIM, W; LAHIRI, GK
Abstract: Tppz [2,3,5,6-tetrakis(2-pyridyl)pyrazine]-bridged complexes [{(L)ClRu}(2)(mu-tppz)](n+) with structurally similar but electronically different ancillary ligands, 2-(2-pyridyl)azoles (L), were synthesized as diruthenium(II) species. Cyclic voltammetry, EPR of paramagnetic states, and UV-vis-NIR spectroelectrochemistry show that the first two reduction processes occur at the tppz bridge and that oxidation involves mainly the metal centers. The mixed valent intermediates from one-electron oxidation exhibit moderate comproportionation constants 10(4) < K-c < 10(5) but appear to be valence-averaged according to the Hush criterion. Redox potentials, EPR, and UV-vis-NIR results show the effect of increasing donor strength of the ancillary ligands along the sequence L-1 < L-2 < L-4 much less than L-3, L-1 = 2-(2-pyridyl)benzoxazole, L-2 = 2-(2-pyridyl)benzthiazole, L-3 = 2-(2-pyridyl)benzimidazolate, L-4 = 1-methyl-2-(2-pyridyl)-1H-benzimidazole. Whereas the mixed valent complexes with L-1 and L-2 remain EPR silent at 4 K, the analogues with L-1 and L-3 exhibit typical ruthenium(III) EPR signals, albeit with some noticeable ligand contribution in the case of the L-3-containing complex, Intervalence charge transfer (IVCT) bands were found in the visible spectrum for the complex with L-3 but in the near-infrared range (at ca. 1500 nm) for the other systems.
URI: http://dx.doi.org/10.1021/ic049605c
http://dspace.library.iitb.ac.in/xmlui/handle/10054/3949
http://hdl.handle.net/10054/3949
Date: 2004


Files in this item

Files Size Format View

There are no files associated with this item.

This item appears in the following Collection(s)

Show full item record

Search DSpace


Advanced Search

Browse

My Account