New coordination features; a bridging pyridine and the forced shortest non-covalent distance between two CO3 2– species† †Electronic supplementary information (ESI) available: Mass Spectrometry and BVS analysis CCDC 996546–996548. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc02491e Click here for additional data file. Click here for additional data file

• Published in: Chemical science (Cambridge) Vol. 6; no. 1; pp. 123 - 131
• Main Authors: Velasco, V., Aguilà, D., Barrios, L. A., Borilovic, I., Roubeau, O., Ribas-Ariño, J., Fumanal, M., Teat, S. J., Aromí, G.
• Format: Journal Article
• Language: English
• Published: Royal Society of Chemistry 08-10-2014
• Subjects: Chemistry
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c4sc02491e

New coordination assemblies furnish a rare crevice pyridine ligand
or encapsulation of the closest not bonded CO
3
2–
species.
The aerobic reaction of the multidentate ligand
2,6-bis-(3-oxo-3-(2-hydroxyphenyl)-propionyl)-pyridine, H
4
L, with
Co(
ii
) salts in strong basic conditions produces the clusters
[Co
4
(L)
2
(OH)(py)
7
]NO
3
(
1
) and
[Co
8
Na
4
(L)
4
(OH)
2
(CO
3
)
2
(py)
10
](BF
4
)
2
(
2
). Analysis of their structure unveils unusual coordination features
including a very rare bridging pyridine ligand or two trapped carbonate anions within one
coordination cage, forced to stay at an extremely close distance (
d
O···O
= 1.946 Å). This unprecedented non-bonding proximity represents a meeting
point between long covalent interactions and “intermolecular” contacts. These original
motifs have been analysed here through DFT calculations, which have yielded interaction
energies and the reduced repulsion energy experimented by both CO
3
2–
anions when located in close proximity inside the coordination cage.