Electrophilic substitution of metal-coordinated pyrazole: nitration, sulfonation and bromination of [Co(NH3)5(pyzH)]3+ (pyzH = pyrazole)
作者:Helen R. Matthews、Lisa C. Bucke、Allan G. Blackman
DOI:10.1016/s0020-1693(97)06120-3
日期:1998.7
Abstract The nitration (HNO 3 /H 2 SO 4 ), sulfonation (oleum) and bromination (Br 2 (aq.), HOBr) of the pyrazole ring of [Co(NH 3 ) 5 pyzH] 3+ (pyzH = pyrazole) are reported. Nitration, sulfonation and bromination with Br 2 (aq.) give the 4-substituted products, while bromination with HOBr gives both di- and tribrominated products. In all cases electrophilic substitution of the coordinated pyrazole appears
摘要[Co(NH 3)5 pyzH] 3+(pyzH =吡唑)的吡唑环的硝化作用(HNO 3 / H 2 SO 4),磺化作用(发烟硫酸)和溴化作用(Br 2(aq。),HOBr)被报道。用Br 2(水溶液)硝化,磺化和溴化得到4-取代的产物,而用HOBr溴化得到二溴和三溴化产物。在所有情况下,与游离吡唑的类似反应相比,配位吡唑的亲电取代似乎都容易进行,这归因于Co(NH 3)5 3+部分的电子性质和吡唑的无效性通过质子化形成失活的吡唑鎓阳离子。未取代的配合物[Co(NH 3)5 pyzH](NO 3)Br 2(C 3 H 19 Br 2 CoN 8 O 3,正交晶,Pbca,a = 13.855(3),b = 13.147(3)的晶体结构),c = 15.383(3)A,α=β=γ= 90°,Z = 8)和磺化配合物[Co(NH 3)5 4-SO 3 pyzH](ClO 4)2·H 2 O(C