A Ni-8 metallacalix[4]arene and a Cu-4 molecular rhomboid: limiting the nuclearity of carboxysalen-like metal complexes

作者：Fondo Matilde; Doejo Jesus; Garcia Deibe Ana M; Sanmartin Matalobos Jesus; Vicente Ramon

来源：CrystEngComm, 2016, 18(35): 6673-6682.

DOI：10.1039/c6ce01384h

Octanuclear [Ni-2(L)(H2O)(2)]4 center dot 7CH(3)OH center dot 12H(2)O (1.7CH(3)OH center dot 12H(2)O) and tetranuclear [Cu-2(HL)(CH3OH)(1.5)(H2O)(1.5)](2)(ClO4)(2)center dot 2CH(3)OH(2.2CH(3)OH) (H4L = 4-carboxysalpn or N,N'-bis(4-carboxysalicylidene)-1,3-propylenediamine) are obtained from similar reactions, the main difference coming from the slightly higher pH of the medium for the nickel reaction vessel. This small disparity of the pH leads to full deprotonation of the ligand in 1 while one of the carboxylic functions remains protonated in 2, making it unable to act as a donor and, therefore, justifying the different nuclearity of both compounds. In any case, the isolation of complexes of H4L with limited nuclearity is remarkable, given that similar carboxysalen-based ligands lead to coordination polymers when the carboxylic functions are partially or fully deprotonated. This indicates that not only the pH of the medium but also the longer propylene spacer of the Schiff base have a fundamental role in the nuclearity of the isolated products. 1.7CH(3)OH center dot 12H(2)O is an odd Ni-8 1,3-alternate metallacalix[4]arene, formed from four symmetry-related [Ni-2(L)(H2O)(2)] metalloligands, joined through the fully deprotonated carboxylic functions. 2 center dot 2CH(3)OH is a molecular rhomboid, built from two [Cu-2(HL)(CH3OH)(1.5)(H2O)(1.5)](+) metallotectons, linked through the only deprotonated carboxylic group of the ligand, the protonated carboxylic moiety remaining uncoordinated. In addition, the magnetic analysis of both polynuclear compounds shows that they are antiferromagnetic in nature and that the magnetic interaction between dinuclear metallotectons is negligible.

• 出版日期2016