合成了新型双齿配体5-羟基-1-(6-氯吡啶-2-基)-1H-吡唑-3-羧酸甲酯及其钯配合物并进行了表征.通过微热量计测定计算了配合物形成的热力学和动力学参数,计算结果显示,该配合物极易形成,在空气和溶液中稳定,可以用作Suzuki反应的催化剂.使用1%(摩尔分数)的催化剂,以2倍量的氢氧化钾为碱,乙醇-水为溶剂,在120℃微波加热2 min,使具有不同电子和空间效应的溴代芳烃和苯硼酸或对甲氧基苯硼酸反应,偶联产物的分离产率可以达到80.7%~95.9%.氯代芳烃也以合适的产率得到偶联产物.
A new N-O ligand 1-(6-chloro-pyridin-2-yl)-5-hydroxy-1H-pyrazole-3-carboxylic acid methyl ester was prepared and structurally analyzed.The solid lattice of the compound at 296 K reveals one dimensional chain structure connected by intermolecular hydrogen bonds[C3—H3…O2,0.2535(17) nm] and halogen bonds[C1—Cl1…O1,0.3161(18) nm,Cl atom as Lewis acid and oxygen atom as Lewis base] interactions.The ligand adds to palladium(Ⅱ) to give high yield of air-stable complex 1 that was fully characterized by infrared(IR) spectroscopy,nuclear magnetic resonance(NMR) spectroscopy and high resolution mass spectrum(HRMS).The dynamic thermochemistry for the formation of complex 1 in liquid-phase was explored by a microcalorimeter.Thermodynamic parameters(the activation enthalpy,the activation entropy and the activation free energy),kinetics parameters(the apparent activation energy,the pre-exponential constant and the reaction order) and rate constants of the coordination reaction were procured.Complex 1 was used as catalyst for the Suzuki cross-coupling between different aryl bromides and phenylboronic acid in water/ethanol with KOH as base under microwave irradiation and afforded the corresponding cross-coupled biaryls in 80.7%—95.9% yields.Furthermore,the reactions of aryl chlorides and phenylboronic acid were also successfully achieved in comparable yields.