“…According to the literature, , it appears to correspond to the most intense diffraction line of the copper oxalate phase. The oxalate ions are known to function as bis-bidentate ligands, and their coordination to two copper ions affords a wide variety of polynuclear compounds. − There are four types of polymerization: 1 X-ray diffraction patterns of (a) dried 1V10Ce, (b) dried 1Cu10Ce, (c) dried 1Cu1V10Ce, (d) 1Cu1V10Ce calcined at 200 °C, and (e) 1Cu1V10Ce calcined at 300 °C (·, copper oxalate phase; ▪, ceria phase).…”
Section: Resultsmentioning
confidence: 99%
“…Copper oxalate is manifested by the different structures mentioned above. It appears that the first, which is constituted by a linear chain of oxalate ions and coordinated in a monodentate fashion, is the more probable form of the copper oxalate but with rather compressed coordination sites than elongated versions. − Furthermore, the unpaired electron is localized in the d z 2 orbital and not in the d x 2 - y 2 orbital of Cu 2+ ions. This compressed coordination can be due to the Cu 2+ ion's radius value (0.73 Å), which is relatively higher than that of the V 4+ ion (0.58 Å).…”
The influence of vanadyl and copper precursors, impregnated on ceria, was evaluated by
X-ray diffraction (XRD), thermal analysis (TG-DSC), and electron paramagnetic resonance
(EPR) of binary and ternary oxides. The formation of a copper oxalate phase from copper
nitrate and vanadyl oxalate was revealed during the preparation of the ternary oxide
(1Cu1V10Ce). Three types of Cu(II) species in the dried copper containing solids were
evidenced: (i) Cu(II) cations with an elongated octahedral symmetry attributed to the copper
nitrate precursor, (ii) a copper oxalate phase with a compressed octahedral symmetry and
(iii) well-dispersed Cu2+ ions on the ceria surface, located in a tetragonally distorted
octahedral crystal field and surrounded by less than six ligands. The dispersion of the copper(II) cations over the ceria support surface was facilitated by the copper nitrate precursor.
The EPR intensities clearly show that the increase of the oxalate precursor content induces
a large fraction of copper that escapes detection by EPR and could be consistent with the
presence of large Cu(II) agglomerates. After the calcination of the solids at 300 °C, only one
copper species was evidenced and assigned to Cu2+ ions located in octahedral sites
tetragonally distorted. The distortion was more pronounced in the presence of vanadium
than in the case of the copper cerium oxide samples. The high dispersion of the copper(II)
cations over the ceria support surface, owing to the copper nitrate precursor, was confirmed
even after its thermal decomposition.
“…According to the literature, , it appears to correspond to the most intense diffraction line of the copper oxalate phase. The oxalate ions are known to function as bis-bidentate ligands, and their coordination to two copper ions affords a wide variety of polynuclear compounds. − There are four types of polymerization: 1 X-ray diffraction patterns of (a) dried 1V10Ce, (b) dried 1Cu10Ce, (c) dried 1Cu1V10Ce, (d) 1Cu1V10Ce calcined at 200 °C, and (e) 1Cu1V10Ce calcined at 300 °C (·, copper oxalate phase; ▪, ceria phase).…”
Section: Resultsmentioning
confidence: 99%
“…Copper oxalate is manifested by the different structures mentioned above. It appears that the first, which is constituted by a linear chain of oxalate ions and coordinated in a monodentate fashion, is the more probable form of the copper oxalate but with rather compressed coordination sites than elongated versions. − Furthermore, the unpaired electron is localized in the d z 2 orbital and not in the d x 2 - y 2 orbital of Cu 2+ ions. This compressed coordination can be due to the Cu 2+ ion's radius value (0.73 Å), which is relatively higher than that of the V 4+ ion (0.58 Å).…”
The influence of vanadyl and copper precursors, impregnated on ceria, was evaluated by
X-ray diffraction (XRD), thermal analysis (TG-DSC), and electron paramagnetic resonance
(EPR) of binary and ternary oxides. The formation of a copper oxalate phase from copper
nitrate and vanadyl oxalate was revealed during the preparation of the ternary oxide
(1Cu1V10Ce). Three types of Cu(II) species in the dried copper containing solids were
evidenced: (i) Cu(II) cations with an elongated octahedral symmetry attributed to the copper
nitrate precursor, (ii) a copper oxalate phase with a compressed octahedral symmetry and
(iii) well-dispersed Cu2+ ions on the ceria surface, located in a tetragonally distorted
octahedral crystal field and surrounded by less than six ligands. The dispersion of the copper(II) cations over the ceria support surface was facilitated by the copper nitrate precursor.
The EPR intensities clearly show that the increase of the oxalate precursor content induces
a large fraction of copper that escapes detection by EPR and could be consistent with the
presence of large Cu(II) agglomerates. After the calcination of the solids at 300 °C, only one
copper species was evidenced and assigned to Cu2+ ions located in octahedral sites
tetragonally distorted. The distortion was more pronounced in the presence of vanadium
than in the case of the copper cerium oxide samples. The high dispersion of the copper(II)
cations over the ceria support surface, owing to the copper nitrate precursor, was confirmed
even after its thermal decomposition.
“…The compound [Cu(ox)(py),] (ox = oxalate, py = pyridine) was obtained as a breakdown oxidized product of [Cu(epgly),] (Hepgly = N-2-ethylphenylglycine), and has been characterized by means of structural and magnetic measurements. The crystals are monoclinic, space group C2/c, with a = 14.088 (3), b = 11.023 (2), c = 8.689(2) A, p = 92.23(3)" and Z = 4. The structure was solved and refined to R = 0.039 and R' = 0.040.…”
“…4 The decomposition product obtained by Norman et al contained 1,2,3,4-tetrahydroxybutane-l,1dicarboxylate anions coordinated to copper,S whereas in another experiment, disodium catena-bis( p-oxa1ato)cuprate(r1) dihydrate was obtained by using molecular oxygen and ascorbic acid. 6 We decided to use hydrogen peroxide as oxidant under aerobic conditions to react with copper(I1) ion and ascorbic acid. With the help of single-crystal X-ray analysis?…”
He k i n ki, Fin Ian dOxidation of a mixture of copper(ii), vitamin C and 2-diethylaminoethanol in the presence of H202 yielded a polymeric catena-ptris(oxalat0)-copper(ii) compound with the Cull ion surrounded by six oxygen atoms of three oxalate ions, each one starting a helical chain.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
