|
NISCAIR ONLINE PERIODICALS REPOSITORY (NOPR) >
NISCAIR PUBLICATIONS >
Research Journals >
Indian Journal of Chemistry -Section A (IJC-A) >
IJC-A Vol.50A [2011] >
IJC-A Vol.50A(02) [February 2011] >
| Title: | Effect of an ancillary ligand on single helix-double helix interconversion in copper complexes. Copper(I)-water bond |
| Authors: | De, Senjuti
Chowdhury, Shubhamoy
Drew, Michael G B
Datta, Dipankar |
| Keywords: | Coordination chemistry
Copper
Helical compounds |
| Issue Date: | Feb-2011 |
| Publisher: | NISCAIR-CSIR, India |
| Abstract: | Reaction of Cu(ClO4)2.6H2O with the 1:2 condensate
of
benzildihydrazone and 2-acetylpyridine,
in methanol in equimolar ratio yields a green compound which upon
recrystallisation from 1:1 CH2Cl2-C6H6
mixture affords [CuL(H2O)](ClO4)2.½C6H6.
The complex crystallises in the space group
P-1 with a = 8.028(11) Å, b = 12.316(17) Å, c = 18.14(3) Å,  = 97.191(10)o,
 = 94.657(10)o and  = 108.039(10)o. It
is single helical with the metal having a distorted trigonal bipyramidal N4O
coordination sphere. The acid dissociation constant of the Cu(I) complex in CH3CN
is 3.34 ± 0.19. The X band EPR spectrum of the compound is rhombic with g1
= 2.43, g2 = 2.10, g3 = 2.02 and A1 = 79.3 x 10-4
cm-1. The Cu(II/I) potential of the complex in CH2Cl2
at a glassy carbon electrode is 0.43 V vs SCE. It is argued that the
copper-water bond persists in the corresponding copper(I) species. Its
implications on the single helix-double helix interconversion in copper
helicates are discussed. DFT calculations at the B3LYP/
6-311G** level shows that the binding
energy of water in the single helical five-coordinate copper(I) species [CuL(H2O)]+
is ~ 40 kJ mol-1. |
| Page(s): | 171-175 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-0975(Online); 0376-4710(Print) |
| Source: | IJC-A Vol.50A(02) [February 2011]
|
|
