Handbook of Solvents - George Wypych - ChemTech - Ventech!

13.1 Solvent effects on chemical reactivity 741
n = 21, r = 0.9973, s = 0.242
and the other deals with the transfer of tetramethylammonium iodide through solvents with
methanol as the reference solvent, 16
where:
0
ΔGtr = 109 . −156 . π∗− 62 . α + 0022 . δH
n = 18, r = 0.997, s = 0.3
n number of solvents
r correlation coefficient
s standard deviation
Figure 13.1.3. Relative orbital energy levels for Cu 2+ in square planar,
tetragonal, and octahedral environments [adapted from ref. 18].
DN = 195.5 - 0.0102ν 0
n = 12, r = 0.990, s = 1.37
We will not finish this section
without noting that there are
also metal complexes available
functioning as color indicators of
the coordination properties of solvents.
18 Thus, Cu(tmen)(acac)
ClO 4, where tmen = N,N,N’,N’tetramethylethylenediamine
and
acac = acetylacetonate, can be
used as a Lewis-basicity indicator,
and Fe(phen) 2(CN) 2, where phen =
1,10-phenanthroline, as a Lewisacidity
indicator. The physical origin
of the underlying color
changes is sketched in the Figures
13.1.3 and 13.1.4, as modified
from ref. 18. These color indicators
can be used as a quick method
for assessing the coordination
properties of solvents, solvent
mixtures, and solutes not yet measured.
This is very expedient since
some classical parameters, particularly
the donor numbers, are arduously
amenable. The following
equation
[13.1.3]
correlates the wave numbersν 0 (in cm -1 ) of the visible band of Cu(tmen)(acac) + and the solvent
donor numbers. Similarly, the acceptor numbers are expressed as a function of the
wave numbers of the long wavelength absorption of Fe(phen) 2(CN) 2,