Estimation of coordination bond energies
1009
0.002 mole [NiCl2(H2O)6] in 20 mL hot MeOH and related
monodentate ligand (5 mL concentrated ammonia or
1.5 mL diethylamine). The mixture was heated to the
boiling point and was set a side for 24–28 h. The Brown
complex crystals were filtered and washed with a small
amount of EtOH and dried in air.
Table 2. The endothermic heat obtained from these mass
losses was measured in Al pan on the Schimadzu DSC-60.
All thermogravimetric analysis were made under nitrogen
atmosphere at a heating rate of 10 °C min-1. DSC mea-
surements were made under nitrogen atmosphere at heating
rate of 5 and 10 °C min-1. DHb, Cp values for H2O, NH3
and Et2NH ligand were taken from literature [10–12].
Every DSC measurement was repeated at least 5 times
with a confidence level of 95%.
Preparation of NiL ꢀ NH3: This green complex was
obtained according to the preparation above with LH2,
[NiCl2(H2O)6] and ammonia.
Preparations of NiL ꢀ H2O and CuL ꢀ H2O: These
complexes were obtained in two steps. About 0.01 mole
LH2 was dissolved in 60 mL EtOH with heating. To this
solution were added a solution of 0.01 mole [NiCl2(H2O)6]
or 0.01 mole [CuCl2(H2O)6] in 40 mL hot water and 2 mL
triethylamine. The mixture was left to stanf for 2–3 days.
After this period NiL or CuL crystals were collected and
dried at 100 °C. About 0.002 mole NiL or CuL complexes
were dissolved in 80 mL EtOH with heating. To this
solution was added 10–20 mL hot water and the mixture
was left to stand for 5–12 days. After this period the green
crystals of NiL ꢀ H2O or CuL ꢀ H2O were filtered and dried
in air.
Results and discussion
Elemental analysis results and some important IR datas as
well as metal-monodental ligand bond lengths relating to
the five complexes that have been prepared are given in
Table 1. These complexes have been prepared according to
the information provided in literature. Molecular models of
these complexes obtained by X-ray diffraction methods are
also given in literature. The mass losses obtained by TG are
the expected values. The thermoanalytical data are given in
Table 2. The recommended calculation method has been
used for the coordinative DMF molecules and appropriate
results were obtained [11, 12]. The coordinative bond
energies found for the main complex are given in Table 3
together with the values of Eq. I. NiSAP ꢀ NH3, NiSAP ꢀ
Et2NH and NiNAP ꢀ Et2NH, which are complexes prepared
with N-(2-hydroxyphenyl) salicylaldimine (SAP) and N-(2-
hydroxyphenyl)-2-hyrdroxy-1-naphthaldimine (NAP), are
diamagnetic with square planar coordination sphere [8–10].
Elemental analysis results and some important IR values
relating to the complexes are given in Table 1. Copper and
nickel analysis were made with the GBC Avanta PM model
Atomic Absorbtion Spectroscopy, C, H, N analysis were
made with Leco 932 CHNS Analyzer equipment. Schi-
madzu DTG-60H was used for thermogravimetric analysis.
Mass loss amounts following the seperation of the NH3,
H2O and Et2NH ligands from the complex are given in
Table 1 Elemental analysis results and some important IR values relating to the complexes
Complex
Elemental analysis (M: Ni2? or Cu2?
)
IR data (cm-1
)
Expected (%) Obtained (%)
t
t
t
t
t d CH2 dC–H (Ar)
C=C (ring)
N–H
C–H (Ar)
C–H (Aliph)
C=N
C
H
N
M
C
H
N
M
NiSAP ꢀ NH3
54.42 4.21 9.76 20.46 54.81 5.17 9.88 21.12 3,140 3,024
–
1,614 1,600
1,473 759
3,240 3,047
3,330
NiSAP ꢀ Et2NH 59.52 5.88 8.16 17.11 59.94 5.92 8.27 17.18 3,244 3,018
2,861
2,934
2,863
2,930
2,854
2,921
2,851
2,923
2,851
2,921
1,617 1,598
1,615 1,597
1,629 1,599
1,626 1,601
1,628 1,601
1,474 757
1,468 757
1,474 756
1,471 755
1,473 759
3,041
NiNAP ꢀ Et2NH 64.16 5.64 7.12 14.93 63.84 5.55 7.65 14.73 3,342 3,031
3,057
NiL ꢀ H2O
CuL ꢀ H2O
NiL ꢀ NH3
57.19 5.08 7.84 16.44 56.70 5.17 7.54 15.79
–
3,027
3,055
3,024
3,054
56.45 5.01 7.74 17.56 56.17 4.48 8.12 17.16
–
57.35 5.37 11.80 16.49 57.41 5.64 10.96 17.04 3,142 3,025
3,249 3,055
3,317
123