Heczko M, Sumińska E, Pinkowicz D, Nowicka B. Crystal Engineering and Photomagnetic Studies of CN-Bridged Coordination Polymers Based on Octacyanidometallates(IV) and [Ni(cyclam)]
2.
Inorg Chem 2022;
61:13817-13828. [PMID:
35998671 PMCID:
PMC9455600 DOI:
10.1021/acs.inorgchem.2c01629]
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Abstract
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A series of new CN-bridged coordination networks of different
dimensionality
and topology was obtained through the modification of reaction conditions
between [Ni(cyclam)]2+ (cyclam = 1,4,8,11-tetraazacyclotetradecane)
and [W(CN)8]4–. The factors determining
the reaction pathway are temperature and addition of the LiCl electrolyte.
The products include three negatively charged frameworks incorporating
Li+ guests: the 1D Li2[Ni(cyclam)][W(CN)8]·6H2O (1) straight chain, the
1D Li2[Ni(cyclam)][W(CN)8]·2H2O (2) zigzag chain, and the 2D Li2[Ni(cyclam)]3[W(CN)8]2·24H2O (3) honeycomb-like network, as well as the 3D two-fold interpenetrating
[Ni(cyclam)]5[Ni(CN)4][W(CN)8]2·11H2O (4) network and the 1D
[Ni(cyclam)][Ni(CN)4]·2H2O (5) chain, which result from partial decomposition of the starting
complexes. Together with the previously characterized 3D [Ni(cyclam)]2[W(CN)8]·16H2O (6)
network, they constitute the largest family of CN-bridged coordination
polymers obtained from the same pair of building blocks. All compounds
exhibit paramagnetic behavior because of the separation of paramagnetic
nickel(II) centers through the diamagnetic polycyanidometallates.
However, the presence of the photomagnetically active octacyanidotungstate(IV)
ions allowed observation of the magnetic superexchange after the violet
light excitation (405 nm) for compound 3, which constitutes
the first example of the photomagnetic effect in a NiII–[WIV(CN)8] system. The photomagnetic
investigations for fully hydrated and dehydrated sample of 3, as well as for the isostructural octacyanidomolybdate(IV)-based
network are discussed.
Six
coordination networks of different dimensionality and
topology can be obtained from the same pair of building blocks: [Ni(cyclam)]2+ and [W(CN)8]4− depending on
reaction conditions. The negatively charged 2D Li2[Ni(cyclam)]3[W(CN)8]2·nH2O microporous network is the first example of the photomagnetic
effect in a NiII−[WIV(CN)8] system.
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