4-Cyanopyridine, a versatile mono- and bidentate ligand. Crystal structures of related coordination polymers determined by X-ray powder diffraction
4-Cyanopyridine (4-CNpy, also known as isonicotinonitrile) can act as a monodentate ligand in transition metal complexes via the pyridine nitrogen atom (N py ), or as a bidentate ligand via both nitrogen atoms (N py and N CN ), resulting in a linear bridge between two metal atoms. Seven new polymeri...
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Published in | CrystEngComm Vol. 19; no. 16; pp. 2216 - 2228 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
2017
|
Subjects | |
Online Access | Get full text |
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Summary: | 4-Cyanopyridine (4-CNpy, also known as isonicotinonitrile) can act as a monodentate ligand in transition metal complexes
via
the pyridine nitrogen atom (N
py
), or as a bidentate ligand
via
both nitrogen atoms (N
py
and N
CN
), resulting in a linear bridge between two metal atoms. Seven new polymeric transition metal compounds, [CuCl
2
(4-CNpy)]
n
(
1b
), [MnCl
2
(4-CNpy)]
n
(
2b
), [NiCl
2
(4-CNpy)
2
]
n
(
3a
), [NiCl
2
(4-CNpy)]
n
(
3b
), [CoBr
2
(4-CNpy)
2
]
n
(
4a
), [NiBr
2
(4-CNpy)
2
]
n
(
5a
) and [NiBr
2
(4-CNpy)]
n
(
5b
), are reported. Compounds
1b
,
2b
,
3b
and
5b
were obtained from the corresponding [M(
ii
)X
2
(4-CNpy)
2
]
n
compounds by careful thermal decomposition under controlled conditions. Compounds
3a
,
4a
and
5a
were synthesized from 4-cyanopyridine and transition metal halides. For all compounds, IR-spectroscopy was used to distinguish between mono- or bi-coordination of the 4-cyanopyridine ligand: in bi-coordinated compounds the asymmetric stretching vibrations of the cyano group
v
as
(CN) are shifted to higher frequencies. All crystal structures were determined from X-ray powder diffraction data. Compounds
1b
,
3a
,
4a
and
5a
consist of polymeric chains of octahedra (double chains for
1b
; single chains for
3a
,
4a
and
5a
), in which 4-cyanopyridine acts as a monodentate ligand
via
the N
py
atom. Compound
1b
exists in two polymorphs, a triclinic (
α
-
1b
) and a monoclinic phase (
β
-
1b
); both exhibit a strong Jahn–Teller distortion of the CuCl
5
N-octahedra. On the other hand,
2b
,
3b
and
5b
exhibit layered structures, in which the 4-cyanopyridine acts as a bidentate ligand. Both nitrogen atoms coordinate to metal atoms, resulting in a linear M(
ii
)-py-CN–M(
ii
) bridge. These are the first examples of Mn and Ni compounds in which two 3d metal atoms are connected by a 4-cyanopyridine bridge. Due to the linearity of this bridge, 4-cyanopyridine lends itself to the construction of new metal–organic frameworks. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1466-8033 1466-8033 |
DOI: | 10.1039/C7CE00425G |