| Abstrakt: |
The mono‐, di‐ or poly‐nuclear copper(II)‐oxalate complexes [Cu(phen)(ox)(H2O)]·H2O (1), {[Cu(μ‐ox)(bpy)]·H2O· 1/2EtOH}n(2), {[Cu(μ‐ox)(bpy)]·2H2O}n(3), [{Cu(NO3)(bpy)(H2O)}2(μ‐ox)] (4) and [{Cu(NO3)(phen)(H2O)}2(μ‐ox)] (5) (ox = oxalato, phen = 1,10‐phenanthroline y bpy = 2,2′‐bipyridine) were prepared by reacting Cu2CO3(OH)2·2H2O or Cu(NO3)2·3H2O salts with glycolic (H2GLYO) or lactic (H2LACO) acids or D‐gluconic acid δ‐lactone (δ‐gluconolactone, H2δ‐Glc) in presence of diimine ancillary ligands. Their crystal structures are reported. The copper(II) atom exhibits a 4+1 five‐coordinate CuN2O2O′ environment in 1, a 4+2 elongated rhombic octahedral CuN2O2O′2stereochemistry in 2or 3, and a 4+1+1 tetragonally elongated octahedral Cu2N2O2O′O″ surrounding in 4or 5. The ligand arrangement and the packing of 5seem to be strongly influenced by intra‐ and inter‐molecular hydrogen bonding as well as π,π‐stacking interactions between C6‐rings from adjacent phen ligands. The most striking feature now reported is the CuII‐mediated oxidation of GLYO2−, LACO2&−;or δ‐Glc2&−;leading to the formation of corresponding CuII‐oxalate derivatives. For the glycolate case a mechanism involving a cleavage of the α‐C‐H bonds is proposed, whereas for lactate or D‐gluconate related systems an oxidative degradation through C‐C bond cleavage are assumed. |
Plný text