Crystal Structure of [Bis(N,N,N′,N′-tetramethylethylenediamine)-O,O′-μ-O,O′-oxalato]dihydroxy Dicopper(II)

Abstract

The oxidative and non-oxidative alkali-catalyzed reactions of Lascorbic acid have attracted great interest, since similar degradation products are formed as in its metabolism. 1,2 The effects of the metal ions on the degradation of Ldehydroascorbic acid and oxalate formation with Co(II) and Gd(II) ions as a decomposition product of L-ascorbic acid in aqueous metal solutions have been clarified. 3,4 The title compound was prepared from mixtures of L-ascorbic acid (0.14 g, 0.8 mmol), N,N,N′,N′-tetramethyl-1,2-diaminoethane (0.12 mL, 0.8 mmol) and copper(II) methoxide (0.1 g, 0.8 mmol) in absolute methanol (70 mL). After filtration, a blue solution was set aside for crystallization at ambient temperature for a few days. Suitable blue crystals were obtained by recrystallization from ethanol.The results of an X-ray structure determination are given in Tables 1 -4

catena-Poly[[[(N,N,N′,N′-tetramethylethylenediamine)copper(II)]-μ-oxalato] tetrahydrate]

“…Les atomes O2, O3, N1 et N2 sont dans un me à me plan qui contient aussi l'ion Cu 2+ , sa de  viation par rapport a Á ce plan est seulement de 0,0094 (8) A Ê . Dans ce plan e  quatorial, les distances moyennes CuÐO [2,007 (2) A Ê ] et CuÐN [2,062 (2) A Ê ; Tableau 1] sont conformes a Á celles trouve  es dans d'autres complexes de cuivre (Cheetham et al, 1999;Jianmin et al, 1995). Les positions axiales sont occupe  es par deux atomes d'oxyge Á ne du groupement oxalate (O1 et O4).…”

“…Les distances CÐC et C O varient respectivement de 1,465 (4) a Á 1,573 (4) A Ê et de 1,245 (3) a Á 1,263 (3) A Ê . Ces valeurs sont de me à me ordre de grandeur que celles releve  es pour les me à mes groupements, dans des compose  s analogues (Jianmin et al, 1995;Hokelek et al, 2000). Ces ions oxalates servent de ponts entre les atomes de cuivre conduisant a  une chaine en zigzag [Cu(C 2 O 4 )-(C 6 H 16 N 2 )] n progressant le long de la direction b (Fig.…”

“…Vue ORTEP-3 (Farrugia, 1997) La cohe  sion de l'e  di®ce cristallin est assure  e par des liaisons hydroge Á ne de type OÐHÁ Á ÁO (Tableau 2 and Fig. 2 (Hokelek et al, 2000). Dans ce dernier, le groupement oxalate forme une liaison bidentate avec un seul cation Cu 2+ donnant lieu a Á la formation de dime Á res.…”

An Oxalate-Bridged Copper(II) Complex Combining Monodentate Benzoate, 2,2′-bipyridine and Aqua Ligands: Synthesis, Crystal Structure and Investigation of Magnetic Properties

“…A detailed search carried out in the Cambridge Structural Database (CSD) [31] for oxalate-bridged copper(II) complexes with ox 2in bis-bidentate coordination mode displayed a total of 423 results, of which 86 correspond to dinuclear complexes that possess two additional ligands besides ox 2-. Out of 86 structures, 66 contain pentacoordinate metal ions bound to only one type of organic ligand such as pyridine [1], 2,2 -bipyridine [11,32], phenanthroline [33,34], ethylenediamine [35], pyrazole [36,37] and imidazole [38] and their derivatives, the coordination sphere being completed by simple inorganic ions such as nitrate [39], chloride [33], hydroxide [40] and perchlorate [1], or by solvent molecules such as water [6], methanol [34], dimethylformamide [41], tetrahydrofuran [42] or acetonitrile [43]. In the 20 remaining structures, all of which have been reported more recently, the metal ions are hexacoordinate and the chemical composition of the complexes, regarding the presence of at least one organic ligand, solvent molecules and simple inorganic ions, is similar to that observed for the pentacoordinate species [8,11,14,15,44,45].…”