Naslov
Coordination-driven self-assembly of thiocyanate complexes of Co(II), Ni(II) and Cu(II) with picolinamide : a structural and DFT study

Autori
Đaković, Marijana ; Vila-Viçosa, Diogo ; Calhorda, Maria Jose ; Popović, Zora

Izvornik
Crystengcomm (1466-8033) 13 (2011); 5863-5871

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
metal complexes; picolinamide; crystal structure; hydrogen bonding; DFT study

Sažetak
The new heteroleptic complexes [M(NCS)2(pia)2] M = Co(II) (1), Ni(II) (2), and [Cu(SCN)2(pia)2] (3), pia = pyridine-2-carboxamide, were synthesized and characterized. Their single crystal X-ray diffraction structures showed octahedral units, with the two thiocyanate ligands occupying cis-positions and binding through the nitrogen atom in Co(II) and Ni(II). In the Cu(II) complex, they were trans and S-bound. The crystal structures display a 2-d structure with NH...S hydrogen bonds for the Co(II) and Ni(II), forming tetrameric units, and are isomorphous with the Zn(II) complex, [Zn(NCS)2(pia)2], and a 2-d structure with NH...N for the Cu(II). DFT calculations were performed on the new complexes and the analogous polymorphs of [Zn(NCS)2(pia)2], including a second one containing dimeric motifs. The calculated vibrational modes of the thiocyanate ligands corroborate with the experimental ones and reflect the coordination mode of the ligand. A comparison between the two Zn(II) polymorphs showed that the NH...S bond in the tetramer is stronger (–7.50 kcal mol–1/metal) than the NH...O bond in the dimer (–4.01 kcal mol–1/metal), indicating a preference for the formation of tetrameric units. The NH...N hydrogen bonds calculated in the Cu(II) crystal are stronger (–9.15 kcal mol–1/metal) than the NH...S ones in Ni(II) and Zn(II).

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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