The role of alkali metal cations in the construction of heterometallic Ni polymeric cyclopropane-1,1-dicarboxylates

• Published in: CrystEngComm Vol. 27; no. 2; pp. 3352 - 3361
• Main Authors: Zorina-Tikhonova, Ekaterina N, Matiukhina, Anna K, Korlyukov, Alexander A, Goloveshkin, Alexander S, Babeshkin, Konstantin A, Efimov, Nikolay N, Alexandrov, Eugeny V, Kiskin, Mikhail A, Eremenko, Igor L
• Format: Journal Article
• Language: English
• Published: 20.05.2025
• ISSN: 1466-8033
• DOI: 10.1039/d4ce01319k

In this work, new Ni II coordination compounds with cyclopropane-1,1-dicarboxylic acid (H 2 cpdc) dianions were synthesized: {[Na 2 Ni(cpdc) 2 (H 2 O) 6 ]·4H 2 O} n ( 1 ), {[K 6 Ni 3 (cpdc) 6 (H 2 O) 10 ]·8H 2 O} n ( 2 ), {[Rb 6 Ni 3 (cpdc) 6 (H 2 O) 12 ]·5.5H 2 O} n ( 3 ), and [Cs 2 Ni(cpdc) 2 (H 2 O) 8 ] n ( 4 ). All complexes contained mononuclear bischelate fragments {Ni II (cpdc) 2 (H 2 O) 2 } 2− bound by alkali atoms in a 1D coordination polymer for 1 , 2D for 2 and 4 , and 3D for 3 . In the topological representation of coordination bonds and ionic interactions, the Ni center represents the 4-c node of underlying (simplified) nets for all the four compounds. Na + , K + , Rb + , and Cs + provide coordination numbers 4, 5&7&8, 6&7&8, and 6 in the underlying nets. The periodicity is higher for compounds with higher coordination numbers of large cations and a less amount of terminal aqua ligands. In the topological representation of ionic interactions, the fragment {Ni(cpdc) 2 (H 2 O) 2 } 2− plays the role of 4-c ( 1-3 ) or 2-c ( 4 ) node of the underlying nets. H-bonds produce highly connected 3D supramolecular networks. The compounds were characterized by single-crystal X-ray diffraction. The DC magnetic data and ab initio calculations revealed that Ni 2+ ions in 2 and 3 possess a positive D value and an "easy-plane" anisotropy type. The radius of alkali metals affects the dimension of Ni II coordination polymers and the magnetic anisotropy.