Kinetics and mechanism of base hydrolysis of mer-[Cr(pic)3]0 and [Cr(ox)2(pic)]2- (pic = picolinate, ox = oxalate)

被引：2
|
作者：
Marai, Hasan [1 ]
Kita, Ewa [1 ]
Wisniewska, Joanna [1 ]
机构：
[1] Nicholas Copernicus Univ, Fac Chem, PL-87100 Torun, Poland
来源：
TRANSITION METAL CHEMISTRY | 2012年 / 37卷 / 01期
关键词：
CHROMIUM PICOLINATE; COMPLEXES; SUBSTITUTION; DISSOCIATION; AQUATION; SALTS; ION;
D O I：
10.1007/s11243-011-9556-1
中图分类号：
O61 [无机化学];
学科分类号：
070301 ; 081704 ;
摘要：
Mer-[Cr(pic)(3)](0) and [Cr(ox)(2)(pic)](2-) undergo successive base hydrolysis to give chromates(III). Dissociation of the first ligand, pic from [Cr(pic)(3)](0) and ox from [Cr(ox)(2)(pic)](2-), proceeds in two stages, namely initial chelate-ring opening followed by slower liberation of the monodentate ligand. Kinetics of both the stages were studied spectrophotometrically in 0.2-0.9 M NaOH solution, under pseudo-first-order conditions. The calculated values of k(obs) were independent of [OH-]. A mechanism is proposed, where the formation of intermediates in the hydroxo form prevents the monodentate ligand from undergoing chelate-ring closure. Evidence for the formation of an intermediate with O-bonded picolinate is given. The effects of pH and the complex composition on the reactivity are discussed.
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页码：55 / 62
页数：8
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