1. Coordination polymers fabricated from Cd(NO3)2 and N,N′,O-pincer-type isonicotinoylhydrazone-based polytopic ligands – an insight from experimental and theoretical investigations.
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Mahmoudi, Ghodrat, Akbari Afkhami, Farhad, Khandar, Ali Akbar, White, Jonathan M., Maniukiewicz, Waldemar, Babashkina, Maria G., Mitoraj, Mariusz P., Sagan, Filip, and Safin, Damir A.
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COORDINATION polymers ,LIGANDS (Chemistry) ,NATURAL orbitals ,HYDROGEN bonding ,DISPERSION (Chemistry) ,CADMIUM - Abstract
Three cadmium(II) coordination polymers, namely {[Cd(HL
I )(NO3 )2 ]·0.5MeOH}n (1), {[Cd(HLII )(NO3 )2 ]·EtOH}n (2), and [Cd2 (LII )2 (NO3 )2 ]n (3), have been self-assembled from Cd(NO3 )2 and N,N′,O-pincer-type isonicotinoylhydrazone-based ditopic ligands (HLI = N′-(pyridin-2-ylmethylene)isonicotinohydrazide and HLII = N′-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide) and have been characterized experimentally and by DFT computations. In compounds 1 and 2, the corresponding ligand is coordinated to the metal center in the keto form and acted as a tetradentate chelating–bridging agent in which the nitrogen atom of the 4-pyridine ring is coordinated to the cadmium center of the neighboring unit, yielding 1D zig-zag coordination polymers. In compound 3, the ligand was singly-deprotonated and is coordinated in the enolic form with the nitrate ion further acted as a bridging agent, yielding a 2D network. It is revealed by the extended transition state natural orbital for chemical valence (ETS-NOCV) charge and energy decomposition scheme that typical hydrogen bonds O–H⋯O and N–H⋯O, which constitute the networks of 1 and 2, though dominated by a classic Coulomb term, are characterized by an equally important London dispersion constituent due to extra π⋯π and C–H⋯X contacts (X = O, H–C, H–N). The architecture of 3 is due to ionic and dative-covalent Cd–X (X = N, O) bonds as well as London dispersion-driven homopolar dihydrogen C–H⋯H–C and C–H⋯O interactions. NOCV-based representation allowed us to determine that hydrogen bonds O–H⋯O are twice weaker than the corresponding N–H⋯O in the networks of 1 and 2. [ABSTRACT FROM AUTHOR]- Published
- 2022
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