Rhodizonate and croconate dianions as divergent hydrogen-bond acceptors in the self-assembly of supramolecular structures

Abstract

The C5O5(2-) and relatively unstable C6O6(2-) dianions, each serving as a hub for binding with a set of convergent NH donor groups of four phenylurea molecules, have been generated in situ and stabilized in nearly isostructural hydrogen-bonded host lattices.

The Raman spectrum of thiourea–oxocarbon adducts

“…The croconate assignment was based on that available in the literature. 20,21 A recent investigation reported the supramolecular structure involving the hydrogen bonding of croconate and phenylurea units, 22 with the direct involvement of the carbonyl moieties of the oxocarbon and the NH 2 groups of phenylurea, but without any sign of interaction involving Table 2. Raman wavenumbers (in cm 1 ) of the adduct (II), thiourea in solution, solid thiourea and sodium croconate, excited at 1064 nm…”

Rhodizonate Metal Complexes with a 2D Chairlike M6 Metal–Organic Framework: [M(C6O6)(bpym)(H2O)]⋅n H2O

“…Theoretical approaches have indicated that the aromaticity decreases as the ring size increases. [6][7][8][9][10] Thus far, just a few rhodizonate salts of K 2 C 6 O 6 , [8] Rb 2 C 6 O 6[10] and some inclusion compounds of urea and thiourea [9] have been structurally well characterized. [2] Accordingly, much research has been carried out on the exploitation of squarate (C 4 O 4 2À ) and croconate (C 5 O 5 2À ) ligands in the construction of versatile coordination polymeric architectures through various binding modes.…”

“…It is thus expected that rhodizonate (C 6 O 6 2À ) has only a small degree of aromatic character. [9] To the best of our knowledge, the crystal structure of a rhodizonate transitionmetal complex, unfortunately, has not yet been reported. [3][4][5] The existence of planar D nh structures has been established on metal salts or complexes chelated by squarate and croconate.…”

“…[10] and some inclusion compounds of urea and thiourea [9] have been structurally well characterized. For example, rhodizonate conforms to nonplanar D 3d and C 2 molecular geometries coexisting in K 2 C 6 O 6 , a D 6h geometry in Rb 2 C 6 O 6 , [nBu 4 N] + 2 C 6 O 6 2À ·4 PhNHCONH 2 and [nBu 4 N] + 2 C 6 O 6 2À ·2 m-OHC 6 H 4 NHCONH 2 ·2 H 2 O, and a planar C 2v molecular geometry in [nBu 4 N] + 2 C 6 O 6 2À…”

Solid-state linear polarized IR-spectroscopy of croconic and rhodizonic acids

“…Oxocarbons, compounds with general formula (C n O n ) 2-and cyclic structures have been extensively studied due to their interesting fundamental chemical aspects and applications in chemical technology and analytical practice [1][2][3][4][5][6][7][8][9][10]. For example, rhodizonic acid has been used as an analytical reagent for Fe, Pb and Ba.…”