1. Introduction
The coordination chemistry of pseudohalogens as ligands in
transition metal complexes has attracted much attention among
researchers in recent decades. Pseudohalogens are an ambidentate
ligand and therefore they can act as a monodentate as well as
bridging ligands [1–7]. The selenocyanate ion is a triatomic ion
and it can also act as an ambidentate ligand and is known to coordinate
with metal ions through either the nitrogen atom or selenium
atom, depending on the nature and coordination
environment surrounding the metal ions [8–12]. Therefore, the
selenocyanate ion can also act as a terminal monodentate ligand
or a bridging ligand like pseudohalogens and can form mononuclear
or polynuclear complexes with transition metals [13–26]. In
the mononuclear complexes, it has been reported that the Se atom
in the SeCN ion is bonded in complexes of metal atoms of class b
character and the N-atom in the SeCN ion is bonded in complexes
of metal atoms of class a character [27–31]. The number of
selenocyanate containing mono- and polynuclear transition metal
complexes is relatively less in the literature as selenium has a weak
affinity towards many transition metal ions.
As our interest is in the synthesis of polynuclear transition
metal complexes with the ligand dbdmp and pseudohalogens, we
are interested in studying the coordination behavior of the selenocyanate
ion with transition metal ions in the presence of the tetradentate
N4-coordinated dbdpm ligand. Here we report on the
syntheses and characterization of mononuclear complexes of the
types [M(NCSe)(dbdmp)]ClO4 [M = Co(II) and Zn(II)], [Ni(dbdmp)
(NCSe)2] and [Cd(dbdmp)(SeCN)2]. The crystal structures of the
complexes were solved by single crystal X-ray diffraction studies
and they showed that the Ni(II) and Cd(II) complexes have six
coordination with a distorted octahedral geometry and the five
coordinated Co(II) and Zn(II) complexes have a distorted trigonal
bipyramidal geometry. In the complex [Cd(SeCN)(dbdmp)2], Cd–
Se coordination is observed, whereas other complexes [Co(II), Ni(II)
and Zn(II)] have M–N coordination of the SeCN ion.
1. 1. Introduction
บทนำเคมีการประสานงานของpseudohalogens The coordination chemistry of pseudohalogens as ligands in
เป็นแกนด์ในเชิงซ้อนโลหะทรานซิได้รับความสนใจมากในหมู่นักวิจัยในทศวรรษที่ผ่านมา transition metal complexes has attracted much attention among
Pseudohalogens researchers in recent decades. Pseudohalogens are an ambidentate
แกนด์และดังนั้นพวกเขาสามารถทำหน้าที่เป็น ligand and therefore they can act as a monodentate as well as
เช่นเดียวกับการแก้แกนด์[ bridging ligands [1- –7] ไอออน 7]. The selenocyanate ion is a triatomic ion
และมันยังสามารถทำหน้าที่เป็นแกนด์ and it can also act as an ambidentate ligand and is known to coordinate
และเป็นที่รู้จักในการประสานงานกับโลหะไอออนผ่านทั้งอะตอมไนโตรเจนหรือซีลีเนียมอะตอมขึ้นอยู่กับลักษณะและการประสานงานสภาพแวดล้อมโดยรอบโลหะไอออน[ - 12] with metal ions through either the nitrogen atom or selenium
atom, depending on the nature and coordination
environment surrounding the metal ions [8–12]. Therefore, the
selenocyanate ion can also act as a terminal monodentate ligand
or a bridging ligand like pseudohalogens and can form mononuclear
or polynuclear complexes with transition metals [13–26]. In
the mononuclear complexes, it has been reported that the Se atom
in the SeCN ion is bonded in complexes of metal atoms of class b
character and the N-atom in the SeCN ion is bonded in complexes
of metal atoms of class a character [27–31]. The number of
selenocyanate containing mono- and polynuclear transition metal
complexes is relatively less in the literature as selenium has a weak
affinity towards many transition metal ions.
As our interest is in the synthesis of polynuclear transition
metal complexes with the ligand dbdmp and pseudohalogens, we
are interested in studying the coordination behavior of the selenocyanate
ion with transition metal ions in the presence of the tetradentate
N4-coordinated dbdpm ligand. Here we report on the
syntheses and characterization of mononuclear complexes of the
types [M(NCSe)(dbdmp)]ClO4 [M = Co(II) and Zn(II)], [Ni(dbdmp)
(NCSe)2] and [Cd(dbdmp)(SeCN)2]. The crystal structures of the
complexes were solved by single crystal X-ray diffraction studies
and they showed that the Ni(II) and Cd(II) complexes have six
coordination with a distorted octahedral geometry and the five
coordinated Co(II) and Zn(II) complexes have a distorted trigonal
bipyramidal geometry. In the complex [Cd(SeCN)(dbdmp)2], Cd–
Se coordination is observed, whereas other complexes [Co(II), Ni(II)
and Zn(II)] have M–N coordination of the SeCN ion.
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