Introduction
Bis-2,6(3,5-dimethyl(pyrazol-1-yl) pyridine (dmpp) is a
terpyridyl type tridendate ligand synthesized at the be-
ginning of the 1990’s [1]. Due to the presence of 5 nitro-
gen donor atoms side by side in the three aromatic rings
dmpp and similar molecules are denoted as strong lig-
ands. Also the planar structure of the three donor atoms
increase this effect. There are many similar studies and
structures dealing with this subject. The structures of
iron(II), copper(II) and cobalt(II) complexes of dmpp
[2–4] and dinuclear structures of Ni(II) [5] have been re-
ported in literature. There are also many studies dealing
with the catalytic effect of some pyrazolyl pyridine
complexes [6–11].
It has been established since 1986 that azide and
thiocyanate ions form m-bridges of end–end (1,1) and
end–on (1.3) types [12, 13]. There are many examples
in literature dealing with the 1,1 and 1,3 bridges
formed by azide and thiocyanate ions [14–19].
In this this study bis-2,6(pyrazol-1-yl)pyridine
(pp) and some methyl derivatives, 2-(3,5-dimethyl-
(pyrazol-1-yl)-6-(pyrazol-1-yl)pyridine (app) and
bis-2,6(3,5-dimethyl(pyrazol-1-yl) pyridine (dmpp)
were synthesized with the intention of forming
polynuclear nickel(II) complexes using azide and
thiocyanate ions. X-ray studies revealed dinuclear
complexes to form with azide ions and mono nuclear
complexes to form with thiocyanate ions. Figure 1
gives the formulas of the ligands pp, app and dmpp.
Thermal analysis, especially thermogravimetry
is an exceptionally effective method in determination
of complex stoichiometry. The mass of the
coordinatively bonded solvent molecules give very
1388–6150/$20.00 Akadémiai Kiadó, Budapest, Hungary
© 2008 Akadémiai Kiadó, Budapest Springer, Dordrecht, The Netherlands
Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 2, 617–624
NICKEL(II) COMPLEXES PREPARED FROM NNN TYPE LIGANDS AND
PSEUDOHALOGENS
*
Synthesis, structure and thermal decomposition
F. Nazli DÏn¸er Kaya
1
, Ingrid Svoboda
2
, Orhan Atakol
3**
, ÜmÏt Ergun
3
, Adnan Kenar
3
, Musa
Sari
4
and Kaan C. Emregül
3
1
Mersin University, Faculty of Pharmacy, Department of Analytical Chemistry, Mersin, Turkey
2
Strukturforschung, FB Materialwissenschaft, Technische Hochschule, Darmstadt Petersenstrasse 23, D-64287 Darmstadt,
Germany
3
Ankara University, Science Faculty, Department of Chemistry, Tando Èan 06100 Ankara, Turkey
4
Gazi University, Faculty of Education, Be êevler Ankara, Turkey
Six nickel(II) complexes, using azide and thiocyanate ions, have been synthesized from bis-2,6(pyrazol-1-yl)pyridine (pp) and
some methyl derivatives, 2-(3,5-dimethyl(pyrazol-1-yl)-6-(pyrazol-1-yl)pyridine (app) and bis-2,6(3,5-dimethyl(pyrazol-1-yl)
pyridine (dmpp) in non-aqueous media. The complex structures were analyzed using elemental analysis, IR spectroscopy and
thermogravimetry. Appropriate crystals of complex, containing azide [Nipp(N
3
)
2
]·MeOH (I) and thiocyanate
[Nidmpp(SCN)
2
·MeOH] (VI) were prepared and the molecular structures determined using X-ray diffraction. Complex I was seen
to be dinuclear as stated in literature, space group P2
1
/n, monoclinic, a=10.503, b=10.681, c=13.291 , b=106.56° and Z=2 whereas
complex VI was found to be mononuclear, space group P2
1
/n, monoclinic, a=8.646, b=12.614, c=20.697 , b=97.18° and Z=2. The
Ni(II) coordination in both complexes were octahedral. Thermogravimetric studies showed azide containing structures to resemble
the characteristics of explosive materials. Coordinative MeOH were seen to leave the structure in thiocyanate containing com-
plexes, followed by irregular degradation above 300°C.
Keywords: azide, crystal structure, nickel(II) complexes, synthesis, thermal analysis, thiocyanate
Fig. 1 The formulas of the ligands pp, app and dmpp
* In dedication to the 66
th
birthday of Prof. Dr. h.c. Hartmut Fuess
** Author for correspondence: atakol@science.ankara.edu.tr