Synthesis, characterization, and kinetic study of complexation of vanadyl acetylacetone with some unsymmetrical N3O schiff bases

Article abstract of DOI:10.1080/15533174.2010.492551

This article reports the synthesis and characterization of some new vanadyl Schiff base complexes, ((N-salicylideneN'-pyrrolidene)-1,2-ethylenediaminato) oxovanadium(IV) [VO (Salpyren)], ((7-methyl-N-salicylidene-N'-pyrrolidene)-1,2- ethylenediaminato) oxovanadium(IV) [VO(Mesalpyren)], ((7-phenylN-salicylidene- N'-pyrrolidene)-1,2-ethylenediaminato) oxovanadium(IV) [VO(Phsalpyren)], ((N-salicylidene-N'-pyrrolidene)-1,3propylenediaminato)oxovanadium(IV) [VO(Salpyrpd)], ((7methyl-N-salicylidene-N'-pyrrolidene)-1,3-propylenediaminato) oxovanadium(IV) [VO(Mesalpyrpd)], ((7-phenyl-N-salicylidene-N'-pyrrolidene)-1, 3-propylenediaminato)oxovanadium(IV) [VO (Phsalpyrpd)]. These complexes were characterized by elemental analyses, IR, UV-Vis, and mass spectra. The kinetics and mechanism of the complex formation in methanol were studied spectrophotometrically. The second order k2 rate constants show the following trend: Mesalpyren > Salpyren > Phsalpyren > Mesalpyrpd > Salpyrpd > Phsalpyrpd The linear plots of kobs vs. the molar concentration of VO(acac)2, the large negative values of ΔS≠ and the low values of ΔH≠ suggest an associative (A) mechanism. Copyright Taylor & Francis Group, LLC.

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Synthesis, Characterization, and Kinetic Study of
Complexation of Vanadyl Acetylacetone with Some
Unsymmetrical N3O Schiff Bases
Zahra Asadi a
a Chemistry Department, College of Sciences , Shiraz University , Shiraz, I. R. Iran
Published online: 13 Jul 2010.
To cite this article: Zahra Asadi (2010) Synthesis, Characterization, and Kinetic Study of Complexation of Vanadyl
Acetylacetone with Some Unsymmetrical N3O Schiff Bases, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-
Metal Chemistry, 40:6, 397-403
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 40:397–403, 2010
Copyright © Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2010.492551
Synthesis, Characterization, and Kinetic Study of
Complexation of Vanadyl Acetylacetone with Some
Unsymmetrical N3O Schiff Bases
Zahra Asadi
Chemistry Department, College of Sciences, Shiraz University, Shiraz, I. R. Iran
In recent years our group has studied synthesis, thermo-
dynamics and kinetics of adduct formation of many metal
Schiff base complexes with donors such as phosphites, amines
and Imidazole derivatives. In our previous work, synthesis
and characterization of new unsymmetrical Schiff base lig-
and was reported, and the thermodynamics of incorporation
of Ni(II), Cu(II), Zn(II) into Schiff bases in methanol solvent
were studied.[8−13]
In the present report, the synthesis and characterization
of some new vanadium(IV) Schiff base complexes and the
kinetics and mechanism of complexation of vanadyl acety-
lacetone with new Schiff bases in MeOH were studied
spectrophotometrically and explained by an associative (A)
mechanism.
This article reports the synthesis and characterization of
some new vanadyl Schiff base complexes, ((N-salicylidene-
Nꢀ-pyrrolidene)-1,2-ethylenediaminato)oxovanadium(IV)
[VO
(Salpyren)], ((7-methyl-N-salicylidene-Nꢀ-pyrrolidene)-1,2-ethy-
lenediaminato) oxovanadium(IV) [VO(Mesalpyren)], ((7-phenyl-
N-salicylidene-Nꢀ-pyrrolidene)-1,2-ethylenediaminato) oxovana-
dium(IV) [VO(Phsalpyren)], ((N-salicylidene-Nꢀ-pyrrolidene)-1,3-
propylenediaminato)oxovanadium(IV)
[VO(Salpyrpd)],
((7-
methyl-N-salicylidene-Nꢀ-pyrrolidene)-1,3-propylenediaminato)
oxovanadium(IV) [VO(Mesalpyrpd)], ((7-phenyl-N-salicylidene-
Nꢀ-pyrrolidene)-1,3-propylenediaminato)oxovanadium(IV) [VO
(Phsalpyrpd)]. These complexes were characterized by elemen-
tal analyses, IR, UV-Vis, and mass spectra. The kinetics and
mechanism of the complex formation in methanol were studied
spectrophotometrically. The second order k2 rate constants show
the following trend: Mesalpyren > Salpyren > Phsalpyren >
Mesalpyrpd > Salpyrpd > Phsalpyrpd The linear plots of kobs vs.
the molar concentration of VO(acac)2, the large negative values
EXPERIMENTAL
of ꢀS
mechanism.
ꢀ= and the low values of ꢀHꢀ= suggest an associative (A)
Materials
All chemicals were used as obtained from Merck, Acros or
Fluka. Anal. Grade solvent from Merck was used without further
purification.
Keywords kinetic, mechanism, Schiff base, synthesis, Vanadium
complex
Instrumental
INTRODUCTION
Light-absorption measurements in the visible region were
made with a Jasco-V-530-UV-vis spectrophotometer equipped
with a Lauda-ecoline-RE thermostat. FT-IR spectra were run on
a Shimadzu FTIR-8300 spectrophotometer. Mass spectra (+ion)
were obtained with QP 1000 mass spectrophotometer.
In recent years, vanadium chemistry has attracted attention
due to its interesting structural features and biological relevance.
Oxovanadium complexes have been shown to catalyze a vari-
ety of reactions. Vanadium is a bioelement involved in various
catalytic (haloproxidasaes, nitrogenases) and inhibitory (e.g.,
toward phosphatases) processes. There have been great efforts
in the past few years to find efficient insulin-mimetic vanadium
complexes. There would be highly active, easily absorbable and
of low toxicity.[1−7]
Synthesis
The Schiff base ligands were synthesized according to the
literature.[8] The vanadyl complexes were prepared under am-
bient conditions. To a hot solution of the unsymmetrical ligand
(2 mmol) in methanol (20 ml), a hot solution of VO(acac)2 (2
mmol) in methanol (10 ml) was added. The mixture was heated
and a few drops of triethylenamine were added. The reaction
mixture was refluxed for 30–60 min. The colored solution was
concentrated and cooled to yield green powder complexes. The
new synthesized complexes (Figure 1) were identified by IR
Received 24 August 2009; accepted 3 May 2010.
The author is grateful to Shiraz University Research Council for its
financial support.
Address correspondence to Zahra Asadi, Chemistry Department,
College of Sciences, Shiraz University, Shiraz 71454, I. R. Iran.
E-mail: zasadi@susc.ac.ir, zahraasadi83@yahoo.com
397

398
Z. ASADI
A
A
H
H
O
O
N
O
N
O
N
N
V
V
N
N
FIG. 1. The structural representation of the oxovanadium(IV) complexes. A=H, CH3, Ph.
spectra (Figure 2), mass spectra (Figure 3), electronic spectra C20H17N3O2V (382.18): C, 63.00(62.86); H, 4.48(4.45); N,
and elemental analysis.
10.84(10.99).
((N-salicylidene-N’-pyrrolidene)-1,2-ethylenediaminato)o-
xovanadium(IV) [VO(Salpyren)]. Yield: 54%
IR(KBr, cm−1) : 989(υV=O), 1150(υC−O), 1448, 1537(υC=C),
((N-salicylidene-N’-pyrrolidene)-1,3-propylenediaminato)
oxovanadium(IV) [VO(Salpyren)]. Yield: 54%
IR (KBr, cm−1): 978 (υV=O), 1068 (υC−O), 1434, 1541
1596, 1620(υC=N), 2927(υC−H).UV.vis : λmax(CHCl3, nm) : (υC=C), 1569, 1598 (υC=N), 2923, 3053 (υC−H). UV.vis:
362. Mass spectra (m/z) = 306 (VO-L)+. Anal. Found (Calc.): λmax(CHCl3, nm): 360. Mass spectra (m/z) = 320 (VO-L)+.
C14H13N3O2V (306.11): C, 55.76(54.93); H, 4.25(4.25); N, Anal. Found (Calc.): C15H15N3O2V (320.24): C, 56.35(56.25);
13.84(13.73).
H, 4.72(4.72); N, 13.15(13.12).
((7-methyl-N-salicylidene-N’-pyrrolidene)-1,2-ethylened-
((7-methyl-N-salicylidene-N’-pyrrolidene)-1,3-propylene-
iaminato)oxovanadium(IV) [VO(Mesalpyren)]. Yield: 50% diaminato)oxovanadium(IV) [VO(Mesalpyren)]. Yield: 54%
IR(KBr, cm−1) : 970(υV=O), 1100(υC−O),1431, 1535(υC=C), IR(KBr, cm−1): 984 (υV=O), 1074 (υC−O), 1462, 1552
1581, 1593(υC=N), 3000 (υC−H).UV.vis: λmax(CHCl3, nm): (υC=C), 1625, 1650 (υC=N), 2912, 3030 (υC−H). UV.vis:
364. Mass spectra (m/z) = 320 (VO-L)+. Anal. Found (Calc.): λmax(CHCl3, nm): 362. Mass spectra (m/z) = 334 (VO-L)+.
C15H15N3O2V (320.12): C, 56.31(56.28); H, 4.65(4.68); N, Anal. Found (Calc.): C16H17N3O2V (334.25): C, 57.42(57.48);
13.21(13.13).
H, 5.11(5.12); N, 12.64(12.57).
((7-phenyl-N-salicylidene-N’-pyrrolidene)-1,2-ethylened-
((7-phenyl-N-salicylidene-N’-pyrrolidene)-1,3-propylene-
iaminato)oxovanadium(IV) [VO(Phsalpyren)]. Yield: 55% diaminato)oxovanadium(IV) [VO(Phsalpyren)]. Yield: 54%
IR(KBr, cm−1): 981(υV=O), 1146(υC−O), 1442, 1535 (υC=C), IR(KBr, cm−1): 980 (υV=O), 1145 (υC−O), 1462, 1552
1569; 1590(υC=N),3062(υC−H).UV.vis
:
λmax(CHCl3, nm): (υC=C), 1581, 1593 (υC=N), 2935, 3051 (υC−H). UV.vis:
362. Mass spectra (m/z) = 382 (VO-L)+. Anal. Found (Calc.): λmax(CHCl3, nm): 364. Mass spectra (m/z) = 396 (VO-L)+.
FIG. 2. IR spectra of VO(salpyren).

COMPLEXATION OF VANADYL ACETYLACETONE
399
FIG. 3. Mass spectra of VO(mesalpyren).
Anal. Found (Calc.): C21H19N3O2V (396.33): C, 63.66(63.64); cells were used. The pseudo-first-order rate constants were
H, 4.04(4.07); N, 10.62(10.60).
calculated by fitting the data to ln[(At-A )/(A0-A )]=kobs
t
∞
∞
(where At =Absorbance at time t; A0 =Absorbance at t=0;
A
=Absorbance at t= ∞) by means of a linear least-squares
∞
Kinetic Measurements
computer program. The second order rate constants k2 were ob-
tained from the slope of the linear plots of kobs vs. [VO(acac)2]
(vanadyl conc.). To determine the activation parameters of
the kinetics, the absorption measurements were carried out at
four different temperatures, i.e., 10, 20, 30 and 40◦C, respec-
Kinetic data were determined spectrophotometrically.
Pseudo-first-order kinetics for complexation of VO(acac)2 with
the ligands were maintained by using much higher VO(acac)2
concentration (∼10–40 times) than that of the ligands. In all
cases (runs from 10-40 0.1◦C), the procedure involves adding
a sample of vanadyl acetylacetone to a solution containing the
substrate under N2 atmosphere. The kinetics were followed
at a predetermined wavelength, λ = 362 nm, where the dif-
ference in absorption between the substrate and the product
was the largest. The temperature was controlled in a ther-
mostated cell compartment at 10–40 0.1◦C, and 10 mm quartz
tively. The activation enthalpy, ꢀH= and the activation entropy,
ꢀ
ꢀS= were obtained from the standard linear Eyring plots of
ꢀ
Equation (1):
ln (k2/T) = −ꢀH#/RT+ꢀS# / R + 23.8
[1]
TABLE 1
Pseudo-first-order rate constants 103kobs (s−1) for the reaction of mesalpyren with VO(acac)2 in MeOH at different temperatures
[Mesalpyren]= 1.44 × 10−4M
103[VO]/M
0.72
1.44
2.16
2.88
3.60
4.32
5.04
5.76
k2/M−1s−1
10◦C
20◦C
30◦C
40◦C
1.3(0.1)
2.0(0.1)
3.5(0.1)
4.7(0.1)
3.2(0.3)
5.0(0.2)
5.2(0.1)
5.8(0.2)
4.7(0.1)
6.2(0.1)
7.7(0.2)
8.3(0.3)
6.7(0.1)
8.1(0.2)
7.0(0.2)
9.11(0.1) 11.3(0.1) 11.9(0.5)
2.1(0.1)
2.9(0.1)
3.7(0.1)
4.4(0.2)
9.9(0.4) 13.2(0.2) 15.1(0.4) 17.0(0.5)
10.4(0.2) 12.6(0.3) 16.6(0.1) 18.8(0.5) 21.6(0.6)
11.6(0.3) 15.5(0.4) 18.6(0.2) 22.8(0.5) 25.2(0.7)
The numbers in parentheses are the standard deviations of kobs
.

400
Z. ASADI
TABLE 2
Pseudo-first-order rate constants 103kobs (s−1) for the reaction of salpyren with VO(acac)2 in MeOH at different temperatures
[Salpyren]= 1.44 × 10−4M
103[VO]/M
0.72
1.44
2.16
2.88
3.60
4.32
5.04
5.76
k2/M−1s−1
10◦C
20◦C
30◦C
40◦C
1.2(0.1)
1.5(0.1)
2.0(0.1)
3.5(0.2)
1.9(0.1)
2.1(0.1)
3.6(0.2)
4.1(0.2)
2.8(0.1)
3.2(0.2)
5.3(0.3)
6.8(0.3)
3.1(0.1)
4.6(0.3)
7.0(0.2)
4.3(0.3)
6.3(0.3)
5.2(0.2)
8.0(0.2)
6.2(0.3)
9.9(0.2) 11.2(0.5)
6.9(0.4)
1.1(0.0)
2.0(0.1)
2.8(0.1)
3.2(0.1)
9.9(0.6) 12.5(0.3) 13.9(0.2) 15.4(0.6)
10.2(0.4) 12.7(0.7) 14.7(0.4) 16.7(0.5) 18.8(0.6)
The numbers in parentheses are the standard deviations of kobs
.
RESULTS AND DISCUSSION
the reaction of VO(acac)2 with Phsalpyren was at 400 and 341
nm. The deviation in isosbestic points were not observed; these
isosbestic points suggest that only one reaction is in progress,
(Equation (3)) which indicates that different products have not
been produced. Also, the interaction of MeOH solvent with
these ligands was tested and it was shown that the interaction
was very slow and did not interfere with the direct reaction
in Equation (3). The activation parameters ꢀH#, ꢀS#were ob-
tained from the standard linear Eyring plots of ln(k2/T) vs.1/T
(Figure 6).
The observed kinetic data are summarized as a function of
[VO(acac)2] and temperature in Tables 1–6.
Under pseudo-first-order conditions, the plots of kobs versus
[VO(acac)2] clearly exhibits a zero intercept within the experi-
mental error (Figure 4); confirming firstly the formation of only
1:1 complex and secondly the complex is essentially stable and
the reverse reaction is negligible.
The rate law of Equation (2) is compatible with the complex
formation according to Equation (3):
The results in Tables 1–6 show that there is a linear rate
dependence on the concentration of the vanadyl acetylace-
tone. A typical plot of kobs vs. vanadyl molar concentra-
tions for Mesalpyrpd at different temperature is shown in
Figure 4. The linear plots of kobs vs. [VO(acac)2] , the large
negative values of ꢀS#and the low ꢀH#values(Table 7) suggest
an associative (A) mechanism for Equation (3).
kobs = k2[VO(acac)2]
[2]
[3]
VO(acac)2 + H2L → VO(L) + 2Hacac
L = salpyren, mesalpyren, phsalpyren, salpyrpd, mesalpyrpd,
phsalpyrpd
The k2 values in Equation (2) are obtained from the slope of
the linear plots of kobsvs. the vanadyl concentration [VO(acac)2]
(Figure 4).
The k2 values trend in M−1s−1for different ligands with
VO(acac)2 at 30◦C is as follows:
mesalpyren salpyren phsalpyren mesalpyrpd salpyrpd phsalpyrpd
3.7 0.1 2.8 0.1 2.5 0.1 0.3 0.0 0.2 0.0 0.1 0.0
k2 (M−1s−1
)
This trend shows that, the k2 values for Schiff bases with
electron releasing methyl group were more than those with
electron withdrawing phenyl group. On the other hand, k2
The spectra in general show clean isosbestic points (Fig-
ure 5). For example the isosbestic points observed at 10◦C for
2.2
10
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
20
1.8
30
40
1.4
1
0.6
0.2
0.5
1.5
2.5
3.5
4.5
5.5
6.5
320
335
350
365
380
395
410
425
440
455
470
103[VO(acac)2] (M)
wavelength(nm)
FIG. 5. The absorption spectra of phsalpyren with VO(acac)2 at 10◦C in
MeOH with the isosbestic points.
FIG. 4. The plots of kobs vs. VO(acac)2 molar concentrations [VO] for
mesalpyrpd at different temperatures.

COMPLEXATION OF VANADYL ACETYLACETONE
401
TABLE 3
Pseudo-first-order rate constants 103kobs (s−1) for the reaction of phsalpyren with VO(acac)2 in MeOH at different temperatures
[Phsalpyren]= 1.44 × 10−4M
103[VO]/M
0.72
1.44
2.16
2.88
3.60
4.32
5.04
5.76
k2/M−1s−1
10◦C
20◦C
30◦C
40◦C
0.9(0.0)
1.0(0.0)
2.2(0.0)
2.3(0.0)
1.1(0.0)
2.2(0.0)
4.3(0.0)
4.5(0.1)
1.2(0.0)
3.9(0.1)
4.6(0.1)
6.7(0.2)
2.0(0.1)
4.8(0.2)
6.8(0.2)
2.7(0.1)
6.0(0.3)
3.0(0.2)
6.8(0.4)
3.6(0.2)
8.1(0.4)
4.3(0.3)
9.1(0.4)
0.7(0.0)
1.6(0.0)
2.5(0.1)
3.0(0.1)
8.4(0.2) 11.0(0.5) 12.5(0.6) 14.6(0.5)
8.0(0.4) 11.0(0.6) 13.2(0.6) 15.0(0.7) 17.4(0.7)
The numbers in parentheses are the standard deviations of kobs
.
TABLE 4
Pseudo-first-order rate constants 104kobs (s−1) for the reaction of mesalpyrpd with VO(acac)2 in MeOH at different temperatures
[Mesalpyrpd]= 1.44×10−4M
103[VO]/M
0.72
1.44
2.16
2.88
3.60
4.32
5.04
5.76
102k2/M−1s−1
10◦C
20◦C
30◦C
40◦C
2.5(0.1)
2.7(0.1)
2.9(0.1)
3.1(0.1)
4.3(0.1)
4.1(0.0)
4.9(0.1)
5.1(0.2)
5.2(0.2)
6.4(0.1)
7.1(0.2)
8.5(0.2)
6.7(0.2)
8.8(0.3) 10.2(0.2)
12.3(0.2)
14.2(0.4)
16.1(0.4)
17.4(0.5)
13.2(0.4)
15.1(0.3)
17.5(0.5)
19.7(0.5)
21.7(0.7)
25.5(0.8)
29.6(0.6)
32.7(0.8)
8.5(0.1) 10.3(0.2) 11.5(0.3)
9.8(0.2) 11.7(0.3) 13.6(0.3)
10.5(0.2) 12.8(0.3) 14.6(0.5)
The numbers in parentheses are the standard deviations of kobs
.
TABLE 5
Pseudo-first-order rate constants 104kobs (s−1) for the reaction of salpyrpd with VO(acac)2 in MeOH at different temperatures
[Salpyrpd]= 1.44 × 10−4M
103[VO]/M
0.72
1.44
2.16
2.88
3.60
4.32
5.04
5.76
102k2/M−1s−1
10◦C
20◦C
30◦C
40◦C
2.0(0.1)
2.1(0.4)
3.0(0.4)
3.0(0.4)
3.3(0.2)
3.6(0.5)
3.6(0.4)
4.2(0.3)
4.2(0.4)
4.0(0.6)
5.2(0.7)
5.1(0.4)
5.3(0.2)
6.4(0.2)
6.3(0.4)
7.2(0.3)
5.9(0.0)
6.9(0.5)
7.2(0.5)
9.2(0.4)
6.7(0.1)
8.0(0.9)
9.0(0.5)
10.9(0.5)
9.4(0.1)
9.6(1.3)
11.2(0.7)
11.8(0.5)
9.8(0.4)
10.8(0.7)
12.8(0.6)
13.8(0.6)
15.4(1.4)
17.0(0.8)
19.7(1.1)
21.9(0.8)
The numbers in parentheses are the standard deviations of kobs
.
TABLE 6
Pseudo-first-order rate constants 104kobs (s−1) for the reaction of phsalpyrpd with VO(acac)2 in MeOH at different temperatures
[Phsalpyrpd]= 1.44×10−4M
103[VO]/M
0.72
1.44
2.16
2.88
3.60
4.32
5.04
5.76
102k2/M−1s−1
10◦C
20◦C
30◦C
40◦C
1.8(0.1)
1.9(0.1)
2.1(0.1)
2.4(0.2)
2.1(0.2)
2.0(0.2)
3.0(0.4)
3.6(0.3)
2.8(0.3)
3.3(0.2)
4.1(0.3)
4.1(0.4)
3.3(0.2)
3.7(0.4)
4.9(0.9)
5.1(0.6)
4.2(0.0)
4.4(0.5)
5.6(0.5)
7.7(0.4)
6.0(0.1)
6.1(0.3)
7.3(0.5)
8.1(0.5)
6.5(0.1)
7.5(0.3)
9.1(0.7)
9.8(0.9)
7.1(0.4)
8.1(0.4)
9.5(0.4)
11.3(0.6)
11.3(0.9)
13.2(1.0)
15.5(0.9)
17.7(1.0)
The numbers in parentheses are the standard deviations of kobs
.

402
Z. ASADI
-6.8
values for phsalpyrpd, salpyrpd, mesalpyrpd were lower than ph-
salpyren, salpyren, mesalpyren, which shows that the trimethy-
lene derivatives are considered to produce a weaker ligand
field than the dimethylene derivatives. This is may be due to
higher flexibility caused by the trimethylene chain on complex
formation.
-7
-7.2
-7.4
-7.6
-7.8
-8
Mesalpyrpd
Salpyrpd
The plot of ꢀH# versus ꢀS#gives a good linear relation-
ship for the reaction of VO(acac)2 with salpyren, mesalpyren,
phsalpyren, salpyrpd, mesalpyrpd, phsalpyrpd, as shown in Fig-
ure 8. The good compensation correlation between ꢀH# and
ꢀS#suggests that an isokinetic relationship exists, which sup-
ports the claim that the same mechanism operates for the com-
plex formation.
Phsalpyrpd
310
320
330
340
350
360
105(1/T)(K-1)
FIG. 6. The Eyring plots for the complexation of VO(acac)2 with different
salpyrpd Schiff bases in MeOH.
CONCLUSION
By considering k2, ꢀS#and ꢀH#values for complexation of
six new Schiff base ligands with VO(acac)2the following con-
clusions have been drawn:
40
1. The k2 values for dimethylene derivatives change accord-
ing to the following trend due to electronic properties:
mesalpyren > salpyren > phsalpyren. Also, this trend is
observed for trimethylene derivatives.
35
6
30
25
5
2. The k2 values for the trimethylene derivatives are lower than
the dimethylene derivatives due to their higher flexibility.
3. The linear plots of kobs vs. [VO(acac)2], the large negative
20
4
15
10
5
ꢀ
values of ꢀS#and the low values of ꢀH= suggest an asso-
ciative (A) mechanism.
2
3
1
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ꢀH#/kJmol−1 ꢀS#/JK−1mol−1 aꢀG#/kJmol−1
Mesalpyren
Salpyren
Phsalpyren
Mesalpyrpd
Salpyrpd
15.3(1.6)
23.0(4.5)
33.3(6.6)
7.7(0.6)
6.4(0.5)
8.6(0.2)
−184.2(5.5)
−161.8(15.1)
−128.9(22.1)
−230.3(1.9)
−237.7(1.7)
−232.6(0.7)
73.0(2.4)
73.6(6.5)
73.7(9.5)
79.8(0.8)
80.8(0.7)
81.4(0.3)
Phsalpyrpd
aCalculated from ꢀG# = ꢀH#- TꢀS# at T=313 K, the numbers in
parentheses are the standard deviations.

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