Naslov
Can self-assembly of copper(II) picolinamide building blocks be controlled?

Autori
Đaković, Marijana ; Vila-Viçosa, Diogo ; Bandeira, Nuno A.G. ; Calhorda, Maria José ; Kozlevčar, Bojan ; Jagličić, Zvonko ; Popović, Zora

Izvornik
Crystengcomm (1466-8033) 15 (2013), 40; 8074-8087

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

Ključne riječi
copper(II) complexes; picolinamide; hydrogen bonding; supramolecular assembly

Sažetak
Four copper(II) derivatives with picolinamide (piaH), [Cu(N3)2(piaH)2] (1), [Cu(NCO)2(piaH)2] (2), [Cu(pia)2].2H2O (3) and [Cu(pia)(piaH)(ClO4)]2 (4) are reported. 1 and 2 were isolated as powders shortly after precipitation, becoming crystalline (3) after prolonged standing in mother liquor. The single crystal X-ray analysis revealed the deprotonation of the amide nitrogen (pia) in both 3 (mononuclear square-planar [Cu(pia-N, N)2] building blocks) and 4 (pia acting as a bridge between copper(II) ion within the dimer). MAGSUS hi•T versus T curves suggest only weak magnetic interactions between the copper(II) species in 3 and 4, though 4 is dinuclear. The magnetic coupling was reproduced by DFT calculations on the experimentally determined structures. The mechanism of formation of compounds 3 and 4 was analyzed by DFT calculations. Models of 1 and 2 underwent transfer of two hydrogen atoms from the piaH ligands to the two axial ligands N3– or NCO– that were released yielding 3. In the reaction leading to 4, the perchlorate is a very weak base cannot deprotonate the piaH ligand and after the first hydrogen transfer the dimer 4 is formed. This reactivity, favoring alternative pathways, may switch off an expected self-assembly process.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA