Structure determination of a copper–histamine croconate complex [Cu(C5O5)(C5H9N3)(OH2)].H2O

Molecular properties of coordination compounds of the croconate ion with first-row sivalent transition metals: a quantum mechanical study

“…H (17) C (1) O (13) O (12) C (5) H (16) O (11) H (20) O (18) H (19) O (6) H (17) H (13) H (14) O (15) O (12) H (16) O ( H (23) O (9) [Cu(…”

“…H (22) O (21) H (23) O(6) H (13) O (7) O (12) C (3) H (14) C (2) O(9) C(4) Cu (8) C (1) H (17) C (5) O (11) O (15) H (16) O (10) H (20) O (18) H (19) O (6) H (17) H (18) O (13) O (7) C (3) C (2) H (16) H (15) O (12) C (4) O (8) Zn (11) C(1) C(5) O (10) H (20) O (14) O (9) H(23) H (19) O (21) H (22) 1383 Ferreira et al Vol. 18, No.…”

“…Over the past years, the free oxocarbon ions as well as their coordination compounds have been widely studied concerning spectroscopic, 3-8 electromagnetic [9][10][11][12] and nonlinear optical properties. [13][14][15][16] Crystallographic structures of the squarate and croconate complexes with first-row transition metals have been described in the literature 9,[17][18][19][20][21][22] showing molecules with an infinite polymeric chain where the metal ions are surrounded by six oxygen atoms on a distorted octraedron. 17,18,22 The oxocarbon ion is usually chelated through oxygen atoms to one metal ion and singly-coordinated to another metal, leaving two of its five oxygen atoms (in the case of croconate) uncoordinated.…”

Self-assembly of new three-dimensional molecular architectures of Cd(II) and Ag(I)–Na(I) using croconate as a building block

“…, Zn(), Mn(), Fe() and Co()] 24-28 and also some complexes of croconate associated with another co-ligand such as imidazole, 29 histamine, 30 2,2Јbipyridine, 31 bis(2-pyridylcarbonyl)amido anion, 32 etc are known. Available structural data dealing with the transition metal croconate complexes show that this ligand can act either as a terminal (Scheme 1, I) 29-32 or as a bridging ligand (Scheme 1, II and III).…”

Synthesis and characterization of cobalt(II) complexes of croconate and dicyanomethylene-substituted derivatives †

“…Though croconate (C 5 ) and rhodizonate (C 6 ) oxocarbons were first synthesized more than 170 years ago, 2 and copper() croconate was first reported by Gmelin in 1841, 3 their co-ordination chemistry remained poorly understood until the rebirth of the field following the discovery of squaric acid (C 4 ) in 1959. 4 Only a few structures of croconato complexes with first row transition-metal ions are known: [M(C 5 O 5 )(H 2 O) 3 ] (M = Cu II , Zn II , Mn II , Fe II ), [5][6][7] and also some complexes with croconate associated with another ligand such as imidazole, 8 histamine, 9 2,2Ј-bipyridine 10 or the bis(2-pyridylcarbonyl)amido anion. 11 Available structural data dealing with transition-metal croconate complexes show that this ligand can act either as a terminal (I) 8-10 or as a bridging ligand (II and III).…”