Oxalic acid reacts with sandwich compounds such as decamethyl ferrocene, decamethyl cobaltocene, bis-benzene chromium and cobaltocene, in the presence of oxygen, via a multi-step process involving oxidation, deprotonation and precipitation, to form crystalline superstructures containing columns of organometallic sandwich cations and hydrogen oxalate anions. Five novel crystalline compounds are reported, namely [Fe(eta(5)-C-5 Me-5)(2)][HC2O4].[H2C2O4](0.5), 1a, [Co(eta(5)-C5Me5)(2)][HC2O4][H2C2O4](0.5), 1b, [Fe(eta(5)-C-5 Me-5)(2)][HC2O4].[H2C2O4], 2, [Cr(eta(6)-C6H6)(2)][HC2O4][H2O], 3, and [Co(eta(5)-C5H5)(2)][HC2O4].[H2C2O4](0.5) [H2O] 4. The anionic network in [M(eta(5)-C5Me5)(2)][HC2O4].[H2C2O4](0.5) (M = Fe, Co) is based on an unusual deca-atomic ring formed by hydrogen oxalate anions linked side-to-side via O(-)-H...O(-) hydrogen bonding interactions. The magnetic behaviour of compounds 1a, 2, and 3 has been investigated by SQUID magnetometry. Both compounds 1a and 2 present weak antiferromagnetic interactions, which are significantly stronger in 1a. The structure of the chloride salt [(eta(5)-C5H5)(2)Co][Cl].[H2C2O4][H2O], 5, is also described.

The Hydrogen Oxalate Anion Allows One-dimensional Columnar Aggregation of Organometallic Sandwich Cations / D. BRAGA; M. ECKTER; M. FRACCASTORO; L. MAINI; F. GREPIONI; A. CANESCHI; R. SESSOLI. - In: NEW JOURNAL OF CHEMISTRY. - ISSN 1144-0546. - STAMPA. - 26:(2002), pp. 1280-1286. [10.1039/b205782d]

The Hydrogen Oxalate Anion Allows One-dimensional Columnar Aggregation of Organometallic Sandwich Cations

CANESCHI, ANDREA;SESSOLI, ROBERTA
2002

Abstract

Oxalic acid reacts with sandwich compounds such as decamethyl ferrocene, decamethyl cobaltocene, bis-benzene chromium and cobaltocene, in the presence of oxygen, via a multi-step process involving oxidation, deprotonation and precipitation, to form crystalline superstructures containing columns of organometallic sandwich cations and hydrogen oxalate anions. Five novel crystalline compounds are reported, namely [Fe(eta(5)-C-5 Me-5)(2)][HC2O4].[H2C2O4](0.5), 1a, [Co(eta(5)-C5Me5)(2)][HC2O4][H2C2O4](0.5), 1b, [Fe(eta(5)-C-5 Me-5)(2)][HC2O4].[H2C2O4], 2, [Cr(eta(6)-C6H6)(2)][HC2O4][H2O], 3, and [Co(eta(5)-C5H5)(2)][HC2O4].[H2C2O4](0.5) [H2O] 4. The anionic network in [M(eta(5)-C5Me5)(2)][HC2O4].[H2C2O4](0.5) (M = Fe, Co) is based on an unusual deca-atomic ring formed by hydrogen oxalate anions linked side-to-side via O(-)-H...O(-) hydrogen bonding interactions. The magnetic behaviour of compounds 1a, 2, and 3 has been investigated by SQUID magnetometry. Both compounds 1a and 2 present weak antiferromagnetic interactions, which are significantly stronger in 1a. The structure of the chloride salt [(eta(5)-C5H5)(2)Co][Cl].[H2C2O4][H2O], 5, is also described.
2002
26
1280
1286
D. BRAGA; M. ECKTER; M. FRACCASTORO; L. MAINI; F. GREPIONI; A. CANESCHI; R. SESSOLI
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/204980
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