双过氧钒配合物与吡啶类配体相互作用的NMR研究

NMR Studies on Interactions between Diperoxovanadate Complex and Pyridine-Like Ligands

为探讨单齿/双齿吡啶类配体对反应平衡的影响,在模拟生理条件下(0.15mol·L-1NaCl溶液),应用多核(1H、13C和51V)多维(COSY,HSQC和HMBC)以及变温NMR技术研究双过氧钒配合物[OV(O2)2(D2O)]-/[OV(O2)2(HOD)]-(简写为bpV)与系列吡啶类配体的相互作用,研究结果表明bpV与有机配体的反应性从强到弱的顺序为:2,2′-联吡啶>2,2′-联吡啶-4,4′-二甲酸根>吡啶>异烟酸根,这说明双齿吡啶类配体配位能力强于单齿配体,而不带羧基的吡啶类配体(单齿或双齿)配位能力强于所对应的带羧基的取代吡啶,竞争配位导致一系列新的6配位(配体为吡啶或异烟酸根)或7配位(配体为2,2′-联吡啶或2,2′-联吡啶-4,4′-二甲酸根)的过氧钒物种[OV(O2)2LL′]n-(LL′=吡啶类配体,n=1,2,3)生成。

To understand how the monodentate/bidentate pyridine-like ligands affect the reaction equilibrium, the interactions between diperoxovanadate complex [OV （O2）2（D2O）]-/[OV （O2）2（HOD）]-（abbr. bpV） and a series of pyridine-like ligands in solution were explored using multinuclear （1H, 13C, and 51V） magnetic resonance, COSY, HSQC, HMBC, and variable temperature NMR in 0.15 mol·L^-1 NaCl ionic medium for mimicking the physiological condition. The reactivity among these organic ligands and bpV are 2,2′-bipyridine 4,4′-dicarboxylate-2,2′-bipyridine pyridine isonicotinate. The experimental results indicated that the coordinating ability of bidentate ligands is stronger than that of monodentate ligands, and the coordinating ability of unsubstituted ligands is stronger than that of corresponding carboxylate substituted ligands. The competitive coordination results in the formation of a series of new six-coordinated （pyridine or isonicotinate） or seven-coordinated （2,2′-bipyridine or 4,4′-dicarboxylate-2,2′-bipyridine） peroxovanadate species [OV（O2）2LL′]n-（LL′= pyridine-like ligands, n=1, 2, 3）.