Hydrogen-Bonded Supramolecular Architectures Based on Tris(Hydranilato)Metallate(III) (M = Fe, Cr) Metallotectons

Here we report on the synthesis and
characterization of two isostructural
mononuclear complexes of formula [(Ph)4P]3[M­(H2An)3]·6H2O (M = Fe­(III) (1) or Cr­(III) (2); H2An = H2C6O42– = dianion of 3,6-dihydroxy-1,4-benzoquinone
(DHBQ)) as suitable metallotectons for the preparation of H-bonded
supramolecular architectures. The crystal structure of 1 consists of homoleptic tris-chelated octahedral complex anions [Fe­(H2An)3]3– surrounded by crystallization
water molecules and (Ph)4P+ cations. The metal
complexes are involved in an extensive network of moderately strong
hydrogen bonds (HBs) between the peripheral oxygen atoms of the ligand
and crystallization water molecules. These interactions are responsible
for the formation of supramolecular layers that run parallel to the a crystallographic axis, showing an unprecedented H-bonded
2D architecture in the family of the anilato-based H-bonded networks.
The supramolecular interactions present in the structure were investigated
analyzing the properties of the Hirshfeld surface (HS), which points
out the crucial role of the HBs in the construction of the overall
supramolecular architecture, whereas the electronic properties of
the metal complex were studied by means of DFT calculations. The magnetic
susceptibility measurements reveal the expected paramagnetism of the
two compounds with quasi-isolated spin centers.